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Deep carbon reductions in California require electrification and integration across economic sectors

Deep carbon reductions in California require electrification and integration across economic sectors Meeting a greenhouse gas (GHG) reduction target of 80% below 1990 levels in the year 2050 requires detailed long-term planning due to complexity, inertia, and path dependency in the energy system. A detailed investigation of supply and demand alternatives is conducted to assess requirements for future California energy systems that can meet the 2050 GHG target. Two components are developed here that build novel analytic capacity and extend previous studies: (1) detailed bottom-up projections of energy demand across the building, industry and transportation sectors; and (2) a high-resolution variable renewable resource capacity planning model (SWITCH) that minimizes the cost of electricity while meeting GHG policy goals in the 2050 timeframe. Multiple pathways exist to a low-GHG future, all involving increased efficiency, electrification, and a dramatic shift from fossil fuels to low-GHG energy. The electricity system is found to have a diverse, cost-effective set of options that meet aggressive GHG reduction targets. This conclusion holds even with increased demand from transportation and heating, but the optimal levels of wind and solar deployment depend on the temporal characteristics of the resulting load profile. Long-term policy support is found to be a key missing element for the successful attainment of the 2050 GHG target in California. Keywords: energy system modeling, renewable energy, long term energy scenarios, electricity system optimization, deep carbon reduction S Online supplementary data available from stacks.iop.org/ERL/8/014038/mmedia 1. Achieving the 2050 GHG target Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further California has become an internationally important test- distribution of this work must maintain attribution to the author(s) and the bed for low-cost, low-GHG energy planning. California’s title of the work, journal citation and DOI. 1748-9326/13/014038C10$33.00 1 2013 IOP Publishing Ltd Printed in the UK Environ. Res. Lett. 8 (2013) 014038 M Wei et al landmark AB32 law mandates a return of State GHG of California emissions [9]. As dictated by the current status emissions to the 1990 level by 2020, and Executive Order of technology, two primary pathways are proposed to achieve S-3-05 sets a goal for the State to reduce emissions to 80% low-GHG transportation and displace petroleum-based fuels: below this level by 2050 [1, 2] . low-GHG biofuels and electrification . This work does not In this work, we take an integrated approach and evaluate consider hydrogen vehicles due to the multiple challenges GHG emissions across the electricity, building, transportation, posed by hydrogen distribution, storage, fuel cell technology, and industrial sectors—90% of the current total—and do and cost, though under certain circumstances this pathway not treat agriculture or non-energy based emissions [3]. could become another viable, low-GHG option for the Taking the 1990 baseline of energy and industry emissions transportation sector. as 405 million metric tons CO -equivalent (MtCO -eq), an 2 2 In our analysis, all biomass is directed towards biofuel 80% reduction gives a 81 MtCO -eq target for California in production and none is made available for electricity, owing 2050 [4]. We take a conservative approach by predominantly to the difficulty in electrifying some transportation modes using technologies that exist in the marketplace or are beyond and the relative abundance of low-GHG sources of electricity. the demonstration stage. In keeping with the technical potential framework used Integrated long-term planning and a portfolio of public in the building and industry sectors, we adopt 94 million policies are being developed to meet GHG targets in Cali- dry tons of biomass for an overall supply of 7.5 billion fornia. Previous work [5–10] has highlighted the electricity gallons gasoline-equivalent in 2050 [6]. This biomass scenario sector as key to deep GHG reduction in California. This study results from high growth in herbaceous and forest residues, complements and expands on previous work by providing improved technical yield recovery, substantial investment a detailed, bottom-up assessment of electricity demand and in additional energy crops, and utilization of abandoned supply. Load profiles for increased efficiency, vehicle electri- agricultural and non-productive forest lands. Consistent with fication, and heating electrification are developed as inputs State Executive Order S-06-06, we limit imported biofuels to to a state-of-the-art variable renewable resource capacity 25% of total supply. Still, total biofuels fall short of projected planning model of the electric power sector. The SWITCH liquid fuel demand by 32%, necessitating a shift to electric model [11–13] is used to explore generation, transmission, transportation. and storage deployment through 2050 in the synchronous A stock turnover model is used to project light- western North American electricity grid, of which California duty electric vehicle deployment, with 45% of passenger represents roughly one-third of total demand. vehicle miles from electricity in 2050. Passenger vehicle We find that meeting the 2050 GHG target is achievable, electrification assumes that plug-in hybrid and battery electric but requires dramatic changes in the way California produces, vehicles quickly enter the market, and by 2050 become delivers, and uses energy. Figure 1 shows the cumulative the majority of the fleet. Vehicle sales adoption curves by impact of measures that can reach the 2050 target (‘Compliant drive train technology are shown in figure S6 (supplementary Case’). Figure 2 shows the radical shift in overall primary material available at stacks.iop.org/ERL/8/014038/mmedia), energy resulting from these measures. Increased efficiency, and recent State policy targets call for similarly aggressive low-GHG electricity, electrification of heating and vehicles, market penetration through 2025 [14]. Fixed, nighttime load and deployment of sustainable biofuels reduce emissions to profiles for electric vehicles are developed as inputs for the just under 100 MtCO -eq in 2050 (figure 1). Thus additional electric sector model below. 81 000 GWh of demand are elements are required to meet the 81 MtCO -eq target, such added to the electric power system in 2050 from vehicle as higher imports of low-GHG biofuels, higher penetration of electrification (figure 1(b)). Aviation, marine transport, and electrification in industry and transportation, or savings from most heavy-duty transport are not electrified due to range energy conservation (see online supplementary material avail- and weight requirements, but other modes, including some able at stacks.iop.org/ERL/8/014038/mmedia). Conservation short-distance trucks, intra-city buses, and rail transport are is highlighted in sections 2 and 3 as an additional element completely electrified. to attain the 80% target. The electricity sector modeling in sections 4 and 5 does not include demand reduction from conservation since there are other pathways to meet the 80% 3. Bottom-up building efficiency and electrification target (e.g., the 100 MtCO -eq case above coupled with higher 2 modeling biofuel imports). Table 1 provides a summary of energy demands and emission intensities for buildings, industry, and Natural gas currently provides most energy for building transportation sectors for 2011 and four 2050 cases. and industry heat, so a major shift in State energy policies and end-use technologies would be required to enable a transition away from fossil fuel in these sectors [15–18]. 2. Transportation electrification and biofuels are For industry, low and medium temperature processes—39% critical of industry fuel demand—are electrified by 2050, totaling Managing transportation sector emissions is vital to achieving the long-term GHG target as it makes up approximately 40% See for example http://gov.ca.gov/news.php?id=17472 (Office of Governor Edmund G Brown, State of California, Executive Order B-16-2012). 6 8 Detailed information describing California climate programs can be Climate Change Programs, California Environmental Protection Agency, found at www.arb.ca.gov/cc/cc.htm (Climate Change Programs, California California Air Resources Board, www.arb.ca.gov/fuels/altfuels/incentives/ Environmental Protection Agency, Air Resources Board). eos0606.pdf. Accessed 1 June 2012. 2 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 1. (a) The California 2050 GHG target of 81 MtCO -eq can be met with a combination of GHG reduction pathways, each of which is insufficient on its own. Shown here is a compliant case combining increased efficiency across sectors [28], clean electricity, electrification of heating and vehicles, biofuel deployment and savings from energy conservation. The GHG savings percentages associated with each pathway relative to the previous level of emissions are shown and are representative of the savings potential for each measure. Note that the magnitude of GHG savings for each pathway depends on the presentation order. An assessment of the policy landscape is shown for each pathway. All pathways lack long-term policy targets, and no enabling policy for heat electrification or conservation currently exists. (b) Electricity system demand. Increased efficiency in the building and industry sector can reduce California’s 2050 demand from the frozen efficiency case by 35%, and conservation can provide a further 16% electricity demand reduction. Increases in electricity demand stem from electrification of building heat, industry process heating, and vehicles. 24 000 GWh of additional demand based on analysis of increased (figure 1(b)), adding 32 000 GWh to the electricity end-use applications by industry sector and the availability load in 2050. of multiple electric-based process heating technologies. In addition to minimizing fossil fuel demand from the Residential and commercial space and water heating are State’s non-electricity energy supply, increased efficiency of fully electrified by 2050 (figure 1(b)) through a transition to electrical devices in all buildings is also assumed [19, 20]. high-efficiency heat pump technology. Without increased efficiency, much higher electricity demand Hourly load profiles for electricity demand from space and greater capacity of generation supply would be required. For reference, we consider a ‘frozen efficiency’ case where and water heating in buildings are developed based on efficiency levels are held at present day levels. historical heating load profiles, disaggregated by California climate zone, and scaled up to displace all remaining A bottom-up stock model is used to simulate efficiency GHG-intensive heating demands within buildings (figure 3). improvements in residential and commercial buildings [21, Electricity demand from water and space heating is greatly 22], achieving 38% electricity savings in 2050 relative to 3 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 2. Primary energy evolution in California from 2011 and 2050 for the compliant case depicted in figure 1. Note the dramatic shift in energy sources over time, with the percentage of primary energy for electricity doubling present levels by 2050. Petroleum-based liquid fuel is sharply reduced and the fossil fuel fraction of primary energy drops from 90% in 2011 to 44% in 2050. Primary energy for combustible fuels (petroleum, natural gas, coal, biomass, biogas) is defined as the higher heating value of the fuel prior to combustion, whereas primary energy for non-combustible fuels (hydroelectric, nuclear, geothermal, solar, wind) is defined as the heat content of net electricity generated. Net energy from imports and exports of electricity to and from California are calculated hourly using the SWITCH model as the fraction imported multiplied by the out-of-State electricity generation minus the fraction exported multiplied by the in-State electricity generation. the frozen efficiency case. For existing buildings, 100% of New plants will replace a large fraction of electricity technically feasible opportunities to improve efficiency on a generation in today’s power system by 2050, representing retrofit or ‘replace on burnout’ basis are applied to eligible an opportunity to transform the State’s current mix of power buildings by 2050 (supplementary material available at plants and increase the reliance on low-GHG power sources. stacks.iop.org/ERL/8/014038/mmedia). Energy savings from Large-scale integrated planning using suitable policies and new construction is similar to California Public Utilities investments is needed to minimize the cost of this transition. Commission initiatives for Zero Net Energy New Construc- In order to leverage the spatial and temporal synergies tion buildings [23]: 100% of new residential (commercial) among two of the most promising low-GHG generation buildings achieve at least 35% (30%) electricity savings by technologies (solar and wind), careful combinations of 2025 (2030) compared to 2005 efficiency standards. investments are needed to ensure low-GHG, low-cost, and Load profiles are synthesized from the mix of end-use reliable electric power. High-quality renewable resources are demands and technologies using a load profile database for unevenly distributed both spatially and temporally throughout both efficiency and building electrification [24]. Efficiency western North America [25]. It is therefore essential to load profiles for 8760 h yr in 14 California climate zones include the entire western North American synchronous and 20 end-uses are synthesized and provided as inputs to the interconnect—the geographic area of the Western Electricity electric sector model. Coordinating Council (WECC)—in an analysis of future Efficiency savings in 2050 are dominated by a California low-GHG electricity supply. small number of end-uses. For residential buildings, 63% The SWITCH electric power system planning model of cumulative efficiency savings come from lighting, is used to explore future electricity scenarios with a refrigeration, and central air-conditioning. For commercial WECC-wide cap on power sector GHG emissions, reaching buildings, just three uses contribute 81% of the savings: 80% below the 1990 level in 2050. Power sector GHG interior lighting, cooling, and refrigeration. allowances are implicitly assumed to be tradable across WECC. The version of SWITCH used in this study minimizes the cost of producing and delivering electricity from present 4. High-resolution electricity sector modeling day until 2050 using a combination of existing grid assets and GHG reduction from electrification is predicated on a shift to new generation, transmission, and storage capacity. low-GHG electricity. Despite aggressive efficiency measures, Shifting vehicle and heating demand toward electricity overall electricity demand in the compliant case is only 10% would drastically change seasonal and diurnal load profiles lower than the frozen case due to increases from transportation (figure 3). By 2050, the load profile exhibits a strong morning peak in winter due to added demand from water heating, and heating. As a result, drastic but technically feasible shifts in the electric power system appear necessary to decarbonize as well as a new evening peak throughout the year due California’s energy system. to electric vehicle charging. In addition, air conditioning 4 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Table 1. Summary table of energy demands and emission intensities for buildings, industry, and transportation sectors for 2011 and four 2050 cases. State population is assumed to increase 60% to 59.5 million residents in 2050 from 37.7 million residents currently. Energy Relative emissions intensity relative to current (2011 D 1) 2050 compliant 2050 compliant (increased (increased 2050 increased efficiency, 2050 increased efficiency, efficiency, low-GHG efficiency, low-GHG low-GHG electricity, low-GHG electricity, 2050 electricity, electrification, 2050 2050 electricity, electrification, 2050 frozen increased electrification, biofuels, frozen increased electrification, biofuels, Energy supply Units 2011 efficiency efficiency biofuels conservation) efficiency efficiency biofuels conservation) Buildings Liquid, solid Tbtu 52 77 54 17 15 1 1 1 1 fuels Gaseous fuel Tbtu 710 1 052 735 227 209 1 1 1 1 Sum Tbtu 762 1 129 789 244 224 Change 48% 30% 69% 8% Electricity GWh 176 500 288 200 178 800 213 400 196 500 1 1 0.12 0.12 Change 63% 38% 19% 8% Industry Liquid, solid Tbtu 496 611 276 130 94 1 1 0.86 0.86 fuels Gaseous fuel Tbtu 1 039 1 255 604 322 232 1 1 0.94 0.94 Sum Tbtu 1 535 1 866 880 452 325 Change 22% 53% 49% 28% Electricity GWh 47 200 81 100 58 400 91 900 66 200 1 1 0.12 0.12 Change 72% 28% 57% 28% Transportation Liquid, solid Bgge 21.4 38.5 20.2 10.6 8.8 1 1 0.50 0.50 fuels Change 80% 48% 48% 17% Electricity GWh 0 0 0 97 000 80 900 1 1 0.12 0.12 Change 17% Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 3. (a) Drastic shifts in load profile are seen from the implementation of efficiency (‘post efficiency’ scenario) and subsequent addition of loads from electric vehicles and heating. The compliant case (‘Base Case’) represents the load profile used as an input to the SWITCH model. One peak and one median demand day per season are shown in the figure for clarity, though the SWITCH model uses six days per season for each decadal time step. (b) WECC-wide electricity generation in 2050 as dispatched by SWITCH for the frozen efficiency load profile (c) WECC-wide electricity generation in 2050 as dispatched by SWITCH for the compliant case from figures 1(b) and 3(a). Note the shift from solar to wind power as the amount of efficiency and vehicle and heating electrification is increased from the frozen efficiency load profile. loads in summer afternoons remain prominent even after new can cost-effectively meet aggressive GHG reduction targets, efficiency measures are introduced, producing an electricity even with drastic changes in load profile shape due to system with high demand periods in both summer and winter. efficiency and large vehicle and heating loads (supplementary We model this load profile separately for each of 50 areas material available at stacks.iop.org/ERL/8/014038/mmedia). within WECC for six hours of each of 24 representative The scenarios explored in this study show that variable days in the decades 2020–2050. Both peak and median renewable resources (wind and solar) could economically load days from each month are represented to ensure that contribute as little as one-third or as much as three-fifths SWITCH plans for average and peak conditions across an of generated power within WECC by 2050. Despite their entire year. In each modeled hour, demand must be met by variability, both wind and solar technologies appear poised to the optimization, as well as capacity and operational reserve supply large amounts of inexpensive, low-GHG electricity to margin constraints to ensure system reliability. Results from the WECC power system of the future. investment optimizations are validated using a full year of The optimal fractions of wind and solar deployment are hourly load and variable renewable resource data. a function of the temporal characteristics of the load profile, with increasing vehicle and heating electrification favoring 5. Many cost-effective electricity generation options wind over solar power (figure 3). As nighttime heating and Using the SWITCH model, we find that the WECC electricity electric vehicle loads increase, the energy and capacity value system in 2050 has a diverse set of generation options that of wind power increases relative to that of solar. Increasing 6 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 4. Average 2050 electricity generation by fuel category, and average 2050 power cost (in $2007 per MWh) for ten electricity scenarios in which WECC-wide power sector emissions are capped at 80% below 1990 levels. The biomass solid CCS scenario includes further GHG reductions. The frozen, no carbon cap scenario does not include a cap on GHG emissions. The compliant case (‘Base Case’) is the starting point on which other sensitivity scenarios are based. Information on specific scenarios can be found in the supplementary material (available at stacks.iop.org/ERL/8/014038/mmedia). The average power cost varies by less than $20 per MWh across GHG-capped scenarios, indicating that many low-cost, low-GHG options exist for the power sector. demand flexibility could incentivize either wind or solar cost and generator availability scenarios. While this result power, depending on their relative delivered costs. is in part dependent on technological improvement driving Using operating reserve requirements and large balancing declining capital costs, sensitivity analyses show that three areas similar to those evaluated in the Western Wind and future supply options with the most uncertain costs—solar Solar Integration Study [26], we find that the majority of photovoltaics, nuclear, and fossil/CCS—are not individually spinning reserves in WECC can be provided by hydroelectric essential to keep the cost of electricity low. In all scenarios, power and storage technologies, with the balance provided total power system cost increases roughly in proportion to by gas-fired technologies. Sub-hourly load balancing does not load, so while increasing demand adds to total expenditures, appear to be a major limitation for achieving deep emissions the average cost per MWh is stable through 2050. Relative to reduction in a future electricity grid with up to 60% of energy a scenario in which no cap on GHG emissions is enforced, from variable renewable generation. achieving 80% GHG reductions in the power sector raises the Nuclear power and fossil fuel generation with CO cost of power by 18%–42%. The tight range of power system capture and sequestration (fossil/CCS) may be attractive costs found amongst a variety of scenarios (figure 4) indicates low-GHG baseload technologies, but neither is essential to that GHG reduction via electrification is a robust strategy, as meeting GHG targets (figure 4). With the costs assumed in the risk of power cost overruns is reduced by the availability this study, generating electricity from fossil/CCS can lower of a portfolio of technologies. the cost of power while meeting emissions targets. Installation of new nuclear power is found to be a backstop against rising 6. Discussion—the need for integrated planning and power costs, but is not cost-effective given our base cost policy assumptions. Greater fractions of energy from variable renewable Long-range planning can ensure that current policies and resources are found to increase the magnitude of transmission pathways are consistent with long-term goals. Policies that and storage deployment (figures S69 and S71 available focus on improving natural gas heating or conventional at stacks.iop.org/ERL/8/014038/mmedia). Power systems in internal combustion engine efficiency without transitioning this study that generate less than half of their electricity away from fossil fuel may be appropriate for the short from variable renewable resources are not found to need term, but are not sufficient for meeting long-term GHG drastic expansion of the transmission system nor large-scale targets. Similarly, the electrification of heating will only be deployment of electric energy storage. However, as the an effective measure for meeting an 80% reduction goal fraction of electricity from variable renewable resources if the electricity supply has a near zero-GHG intensity. exceeds fifty per cent, increasing amounts of transmission The interaction among different sectors and various GHG- and storage are installed in order to spatially and temporally reduction pathways should continue to be an active area of move electricity from the point of generation to the point of research and optimization. consumption. The average cost per MWh of electricity stays relatively Technology does not appear to be the limiting factor for constant between present day and 2050 across a range of the State to meet its economy-wide 2050 GHG emissions 7 Environ. Res. Lett. 8 (2013) 014038 M Wei et al target, though this conclusion is predicated upon ample industry) with piecewise additive scenarios for energy low-GHG biomass supplies (with little or no associated demand and energy supply. First, energy efficiency is indirect land use impacts), steady technological development applied across sectors, then clean electricity is added, and cost reduction of existing technologies, and more followed by electrification, low carbon biofuels, and then modest economic growth than assumed in other studies [5, energy conservation. Electricity and fuel supply mixes 6]. Much of the technology already exists for increased were developed to meet overall demand subject to biofuel electrification and building efficiency, but may need policy availability and GHG constraints for electricity. GHG support to achieve cost-effective production at scale and emissions were calculated for each scenario based on more importantly, to induce widespread adoption (tables S1 overall energy demands and carbon intensity of energy and S2 available at stacks.iop.org/ERL/8/014038/mmedia). supplies. Assumptions for the boundaries and scope of Plug-in electric vehicles are being rapidly developed by GHG emission treatment are discussed in the supplementary the automotive sector, but there is less activity in other material (available at stacks.iop.org/ERL/8/014038/mmedia). transportation sectors. Availability of biomass and low-GHG Energy demand for a frozen efficiency case was first process development are pivotal for reducing fuel-use GHG estimated as a reference case with growth rates informed emissions. by historical trends and other studies. An energy efficiency In addition to technological solutions, substantial case was then developed assuming that technical potential reductions are also possible from conservation measures [27]. levels of efficiency are achieved across all three sectors. Preliminary modeling of these GHG-saving measures was A low-GHG electricity supply was added to this scenario conducted based on historical trends in non-energy behaviors (energy supply modeling is described below). Fuel-switching including public health, safety, and diet. By 2050, as much as was introduced by assuming wide spread electrification from 16% of GHG emissions could be conserved by measures such gasoline-based internal combustion engines to electrified as reductions in vehicle-miles traveled, eco-driving, increased or partially electrified passenger vehicles and from largely energy conservation, improved diets, waste reduction, and natural gas based heating processes to electrified heating increased recycling (section 9, supplementary material in buildings and industry. Further carbon reduction was available at stacks.iop.org/ERL/8/014038/mmedia). Human achieved by assuming technical potential availability of liquid and social factors should be a topic for further research, biofuels and finally by assuming conservation measures are as they are directly coupled with public policy, technology aggressively adopted. deployment, and market development. Energy demand was disaggregated into building, trans- Expansion of California’s policy framework is needed to portation, and industry sectors for California. Estimates enable energy system changes suggested herein. Aggressive utilized a median population and economic growth forecast codes and standards will be required to meet building, vehicle, based on State and California Energy Commission (CEC) esti- and industry efficiency targets. While efficiency is already a mates, respectively. Building demands for electricity and fuel focus for the State, implementation and adoption of additional (e.g., natural gas for heating) were developed for residential efficiency measures is critical, especially for building retrofits. and commercial buildings as described in the supplementary Policies are currently in place for both vehicle electrification material (available at stacks.iop.org/ERL/8/014038/mmedia) and low-GHG biofuels, but will need extension and expansion and further disaggregated into single/multi-family units and to meet the 2050 climate goal. Multiple barriers exist for new/existing buildings. Stock turnover analysis was done building electrification, and policy development is urgently for a comprehensive set of end-use demands. Commercial needed to ensure the transition to electrified heating. An 80% buildings demand estimates utilized historical trends of reduction in electricity sector emissions can be ensured with energy demand per square foot of space by building type. a continuation and expansion of aggressive renewable energy Electricity demand for the rest of the Western Electricity and/or GHG targets in the future. Coordination Council geographic region was estimated from a Meeting the State’s 2050 GHG target is found to synthesis of US Energy Information Administration data and be feasible but requires a portfolio of measures and a regional utility forecasts. commitment to integrating and coordinating policies in the Transportation demand estimates utilized vehicle stock electricity, buildings, transportation, and industrial sectors. modeling for passenger vehicles and aviation with projections The GHG reduction measures put forward here include an increase in the efficiency of energy use for all sectors, a for other transportation modes consistent with State or drastic decrease in the GHG intensity of electricity and liquid federal models. Stock modeling assumptions of vehicles fuels, and a substitution of end-use fuel consumption for per capita, vehicle-miles travelled (VMT) per vehicle, and electricity. Behavioral factors may also be able to play an market penetrations by vehicle drivetrain (internal combustion important role in GHG emission reduction. Long-term policy engines, hybrid electric vehicles, plug-in hybrid vehicles, and support is found to be a key missing element for the successful battery electric vehicles) are described in the supplementary attainment of the 2050 GHG target in California. material (available at stacks.iop.org/ERL/8/014038/mmedia). Industry demand estimates employed sector-based (oil and gas, food and beverage, etc) economic growth projections 7. Materials and methods from the CEC. Future electricity and fuel demands were projected for The energy efficiency scenario utilized technical potential three economic sectors (buildings, transportation, and estimates for each sector. The building sector employed 8 Environ. Res. Lett. 8 (2013) 014038 M Wei et al a list of over 200 unique efficiency measures while References the transportation sector adopted fuel efficiency potential [1] Commission of European Communities 2007 Limiting Global from existing national and State studies. Industry technical Climate Change to 2 Degrees Celsius: The Way Ahead for potential estimates were based on CEC reports disaggregated 2020 and Beyond (available at http://eur-lex.europa.eu/ by industry sector and end-use (process heating, boiler-based LexUriServ/site/en/com/2007/com2007 0002en01.pdf, systems, motor systems, heating, ventilation, air-conditioning, accessed 1 July 12) etc). [2] California Institute for Energy and Environment 2012 Electrification projections are based on stock modeling California Vulnerability and Adaption Study (available at http://uc-ciee.org/climate-change/california-vulnerability- for building water and space heating and for passenger and-adaptation-study, accessed 1 August 12) vehicles assuming aggressive transition to electricity-based [3] Jackson S 2009 Parallel pursuit of near-term and long-term heating systems in buildings starting in 2015 and to alternative climate mitigation Science 326 526–7 passenger vehicles in transportation, respectively, with market [4] California Environmental Protection Agency Air Resources penetration assumptions described in the supplementary Board 2012 California Greenhouse Gas Inventory for 1990 (available at www.arb.ca.gov/cc/inventory/pubs/reports/ material (available at stacks.iop.org/ERL/8/014038/mmedia). appendix a1 inventory ipcc sum 1990.pdf, accessed The carbon savings potential for energy conservation 10 June 12) was estimated using a simple adoption rate model of energy [5] Williams J H, DeBenedictis A, Ghanadan R, Mahone A, saving actions. From a database of historical non-energy Moore J, Morrow W R III, Price S and Torn M S 2012 The actions, long-term adoption rates were estimated for a set technology path to deep greenhouse gas emissions cuts by 2050: the pivotal role of electricity Science 335 53–9 of conservation actions in home energy usage and passenger [6] California Council on Science and Technology 2011 vehicle mile reduction, as well as a number of other measures California’s Energy Future—The View to 2050 (available at in diet, recycling, and consumption. Carbon savings as http://ccst.us/publications/2011/2011energy.pdf, accessed a function of time were estimated by calculating carbon 1 July 12) intensities for electricity (CO =kWh) and transportation [7] Long J C S 2011 Piecemeal cuts won’t add up to radical reductions Nature 478 429 (CO =VMT). [8] European Climate Foundation 2010 ROADMAP 2050: A Low-GHG electricity modeling utilized a high-resolution Practical Guide to a Prosperous, Low-GHG Europe variable renewable resource capacity planning model (available at www.roadmap2050.eu, accessed 1 July 12) (SWITCH) of the interconnected Western North American [9] Yang C, Ogden J M, Sperling D and Hwang R 2011 grid. SWITCH used spatially resolved, time-synchronized California’s Energy Future: Transportation Energy Use in California (Sacramento, CA: California Council on Science hourly solar, wind, and demand data to explore future low and Technology) (available at http://ccst.us/publications/ carbon electricity scenarios. Optimizations minimized the 2011/2011transportation.pdf, accessed 1 July 2012) cost of power between present day and 2050 while subject [10] Jacobson M Z and Delucchi M A 2011 Providing all global to reliability and policy constraints. Carbon emissions were energy with wind, water, and solar power, part I: constrained to reach 80% below 1990 levels in the year 2050. technologies, energy resources, quantities and areas of infrastructure, and materials Energy Policy 39 1154–69 Biofuel supply estimates were made with all biomass [11] Fripp M 2008 Optimal investment in wind and solar power in directed to liquid biofuels and resultant biofuel assumed to California PhD Dissertation University of California replace oil-based liquid fuel. Biomass and biofuel availability Energy and Resources Group projections utilized technical potential assumptions for in- [12] Nelson J, Johnston J, Mileva A, Matthias Fripp M, Hoffman I, State biomass supply, biomass supply mix, biofuel yield, and Petros-Good A, Blanco C and Kammen D M 2012 life-cycle carbon emission associated with biofuel production. High-resolution modeling of the western North American power system demonstrates low-cost and low-GHG futures Biofuel production was assumed to replace gasoline in Energy Policy 43 436–47 the transportation sector. Sources for biomass materials [13] Fripp M 2012 SWITCH: a planning tool for power systems availability include earlier reports from Oak Ridge National with large shares of intermittent renewable energy Environ. Laboratory, the University of California, Berkeley, and the Sci. Technol. 46 6371–8 University of California, Davis. [14] State of California 2013 ZEV Action Plan A Roadmap Toward 1.5 Million Zero-Emission Vehicles on California All methods and key assumptions are described more Roadways by 2025 First Edition (Governor’s Interagency fully in the supplementary material available online at (stacks. Working Group on Zero-Emission Vehicles, Office of iop.org/ERL/8/014038/mmedia) . Governor Edmund G Brown Jr) (available at http://opr.ca. gov/docs/Governor’s Office ZEV Action Plan (02-13). pdf, accessed 19 February 13) Acknowledgments [15] Schmidt P S 1984 Electricity and Industrial Productivity, A Technical and Economic Perspective (New York, NY: We thank the California Energy Commission for support. This Pergamon) paper reflects the views of the authors and does not necessarily [16] Electric Power Research Institute 2009 The Potential to reflect the view of the California Energy Commission or the Reduce CO Emissions by Expanding End-Use Applications of Electricity EPRI Report 1018871 State of California. DMK thanks the Class of 1935 of the [17] US Department of Energy 2007 Improving Process Heating University of California, Berkeley, and the Karsten Family System Performance: A Sourcebook for Industry 2nd edn Foundation. (Golden, CO: US Department of Energy Industrial None of the authors have a conflict of interest for this Technologies Program and Industrial Heating Equipment work. Association) 9 Environ. Res. Lett. 8 (2013) 014038 M Wei et al [18] Greenblatt J, Wei M and McMahon J 2012 California’s [23] California Public Utilities Commission 2008 California Long Energy Future: Buildings and Industrial Energy Efficiency Term Energy Efficiency Strategic Plan (available at www. (Sacramento, CA: California Council on Science and cpuc.ca.gov/NR/rdonlyres/D4321448-208C-48F9-9F62- Technology) (available at http://ccst.us/publications/2011/ 1BBB14A8D717/0/EEStrategicPlan.pdf, accessed 1 July CEF%20index.php, accessed 15 February 2013) 2012) [19] Masanet E et al 2013 Estimation of Long-Term [24] California Energy Commission 2006 California Commercial Energy-Efficiency Potentials for California Buildings and Building End-Use Survey (Report No CEC-400-2006-005) Industry (Public Interest Energy Research Program Report, (Sacramento, CA: California Energy Commission) Draft Report) (Sacramento, CA: California Energy [25] Hand M M, Baldwin S, DeMeo E, Reilly J M, Mai T, Arent D, Commission) Porro G, Meshek M and Sandor D (ed) 2012 Renewable [20] Rufo M W and North A S 2007 Assessment of Long-Term Electricity Futures Study (Entire Report) (Report No Electric Energy Efficiency Potential in California’s NREL/TP-6A20-52409) (Golden, CO: National Renewable Residential Sector (PIER Energy-Related Environmental Energy Laboratory) 4 volumes Research Report Report No CEC-500-2007-002) [26] National Renewable Energy Laboratory 2010 Western Wind (Sacramento, CA: California Energy Commission) and Solar Integration Study (Report No [21] Itron, Inc. 2008 California Energy Efficiency Potential Study NREL/SR-550-47434) (Golden, CO: National Renewable CALMAC Study ID: PGE0264.01 (available at www. Energy Laboratory) calmac.org/startDownload.asp?Name=PGE0264 Final [27] Jones C M and Kammen D M 2011 Quantifying carbon Report.pdf&Size=5406KB, accessed 1 July 2012) footprint reduction opportunities for US households and [22] Palmgren C, Stevens N, Goldberg M, Barnes R and communities Environ. Sci. Technol. 45 4088–95 Rothkin K 2010 2009 California Residential Appliance [28] Sullivan D, Wang D and Bennett D 2011 Essential to energy Saturation Study (Report No CEC-200-2010-004) efficiency, but easy to explain: frequently asked questions (Sacramento, CA: California Energy Commission) about decoupling Electr. J. 24 56–70 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Environmental Research Letters IOP Publishing

Deep carbon reductions in California require electrification and integration across economic sectors

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1748-9326
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10.1088/1748-9326/8/1/014038
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Abstract

Meeting a greenhouse gas (GHG) reduction target of 80% below 1990 levels in the year 2050 requires detailed long-term planning due to complexity, inertia, and path dependency in the energy system. A detailed investigation of supply and demand alternatives is conducted to assess requirements for future California energy systems that can meet the 2050 GHG target. Two components are developed here that build novel analytic capacity and extend previous studies: (1) detailed bottom-up projections of energy demand across the building, industry and transportation sectors; and (2) a high-resolution variable renewable resource capacity planning model (SWITCH) that minimizes the cost of electricity while meeting GHG policy goals in the 2050 timeframe. Multiple pathways exist to a low-GHG future, all involving increased efficiency, electrification, and a dramatic shift from fossil fuels to low-GHG energy. The electricity system is found to have a diverse, cost-effective set of options that meet aggressive GHG reduction targets. This conclusion holds even with increased demand from transportation and heating, but the optimal levels of wind and solar deployment depend on the temporal characteristics of the resulting load profile. Long-term policy support is found to be a key missing element for the successful attainment of the 2050 GHG target in California. Keywords: energy system modeling, renewable energy, long term energy scenarios, electricity system optimization, deep carbon reduction S Online supplementary data available from stacks.iop.org/ERL/8/014038/mmedia 1. Achieving the 2050 GHG target Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further California has become an internationally important test- distribution of this work must maintain attribution to the author(s) and the bed for low-cost, low-GHG energy planning. California’s title of the work, journal citation and DOI. 1748-9326/13/014038C10$33.00 1 2013 IOP Publishing Ltd Printed in the UK Environ. Res. Lett. 8 (2013) 014038 M Wei et al landmark AB32 law mandates a return of State GHG of California emissions [9]. As dictated by the current status emissions to the 1990 level by 2020, and Executive Order of technology, two primary pathways are proposed to achieve S-3-05 sets a goal for the State to reduce emissions to 80% low-GHG transportation and displace petroleum-based fuels: below this level by 2050 [1, 2] . low-GHG biofuels and electrification . This work does not In this work, we take an integrated approach and evaluate consider hydrogen vehicles due to the multiple challenges GHG emissions across the electricity, building, transportation, posed by hydrogen distribution, storage, fuel cell technology, and industrial sectors—90% of the current total—and do and cost, though under certain circumstances this pathway not treat agriculture or non-energy based emissions [3]. could become another viable, low-GHG option for the Taking the 1990 baseline of energy and industry emissions transportation sector. as 405 million metric tons CO -equivalent (MtCO -eq), an 2 2 In our analysis, all biomass is directed towards biofuel 80% reduction gives a 81 MtCO -eq target for California in production and none is made available for electricity, owing 2050 [4]. We take a conservative approach by predominantly to the difficulty in electrifying some transportation modes using technologies that exist in the marketplace or are beyond and the relative abundance of low-GHG sources of electricity. the demonstration stage. In keeping with the technical potential framework used Integrated long-term planning and a portfolio of public in the building and industry sectors, we adopt 94 million policies are being developed to meet GHG targets in Cali- dry tons of biomass for an overall supply of 7.5 billion fornia. Previous work [5–10] has highlighted the electricity gallons gasoline-equivalent in 2050 [6]. This biomass scenario sector as key to deep GHG reduction in California. This study results from high growth in herbaceous and forest residues, complements and expands on previous work by providing improved technical yield recovery, substantial investment a detailed, bottom-up assessment of electricity demand and in additional energy crops, and utilization of abandoned supply. Load profiles for increased efficiency, vehicle electri- agricultural and non-productive forest lands. Consistent with fication, and heating electrification are developed as inputs State Executive Order S-06-06, we limit imported biofuels to to a state-of-the-art variable renewable resource capacity 25% of total supply. Still, total biofuels fall short of projected planning model of the electric power sector. The SWITCH liquid fuel demand by 32%, necessitating a shift to electric model [11–13] is used to explore generation, transmission, transportation. and storage deployment through 2050 in the synchronous A stock turnover model is used to project light- western North American electricity grid, of which California duty electric vehicle deployment, with 45% of passenger represents roughly one-third of total demand. vehicle miles from electricity in 2050. Passenger vehicle We find that meeting the 2050 GHG target is achievable, electrification assumes that plug-in hybrid and battery electric but requires dramatic changes in the way California produces, vehicles quickly enter the market, and by 2050 become delivers, and uses energy. Figure 1 shows the cumulative the majority of the fleet. Vehicle sales adoption curves by impact of measures that can reach the 2050 target (‘Compliant drive train technology are shown in figure S6 (supplementary Case’). Figure 2 shows the radical shift in overall primary material available at stacks.iop.org/ERL/8/014038/mmedia), energy resulting from these measures. Increased efficiency, and recent State policy targets call for similarly aggressive low-GHG electricity, electrification of heating and vehicles, market penetration through 2025 [14]. Fixed, nighttime load and deployment of sustainable biofuels reduce emissions to profiles for electric vehicles are developed as inputs for the just under 100 MtCO -eq in 2050 (figure 1). Thus additional electric sector model below. 81 000 GWh of demand are elements are required to meet the 81 MtCO -eq target, such added to the electric power system in 2050 from vehicle as higher imports of low-GHG biofuels, higher penetration of electrification (figure 1(b)). Aviation, marine transport, and electrification in industry and transportation, or savings from most heavy-duty transport are not electrified due to range energy conservation (see online supplementary material avail- and weight requirements, but other modes, including some able at stacks.iop.org/ERL/8/014038/mmedia). Conservation short-distance trucks, intra-city buses, and rail transport are is highlighted in sections 2 and 3 as an additional element completely electrified. to attain the 80% target. The electricity sector modeling in sections 4 and 5 does not include demand reduction from conservation since there are other pathways to meet the 80% 3. Bottom-up building efficiency and electrification target (e.g., the 100 MtCO -eq case above coupled with higher 2 modeling biofuel imports). Table 1 provides a summary of energy demands and emission intensities for buildings, industry, and Natural gas currently provides most energy for building transportation sectors for 2011 and four 2050 cases. and industry heat, so a major shift in State energy policies and end-use technologies would be required to enable a transition away from fossil fuel in these sectors [15–18]. 2. Transportation electrification and biofuels are For industry, low and medium temperature processes—39% critical of industry fuel demand—are electrified by 2050, totaling Managing transportation sector emissions is vital to achieving the long-term GHG target as it makes up approximately 40% See for example http://gov.ca.gov/news.php?id=17472 (Office of Governor Edmund G Brown, State of California, Executive Order B-16-2012). 6 8 Detailed information describing California climate programs can be Climate Change Programs, California Environmental Protection Agency, found at www.arb.ca.gov/cc/cc.htm (Climate Change Programs, California California Air Resources Board, www.arb.ca.gov/fuels/altfuels/incentives/ Environmental Protection Agency, Air Resources Board). eos0606.pdf. Accessed 1 June 2012. 2 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 1. (a) The California 2050 GHG target of 81 MtCO -eq can be met with a combination of GHG reduction pathways, each of which is insufficient on its own. Shown here is a compliant case combining increased efficiency across sectors [28], clean electricity, electrification of heating and vehicles, biofuel deployment and savings from energy conservation. The GHG savings percentages associated with each pathway relative to the previous level of emissions are shown and are representative of the savings potential for each measure. Note that the magnitude of GHG savings for each pathway depends on the presentation order. An assessment of the policy landscape is shown for each pathway. All pathways lack long-term policy targets, and no enabling policy for heat electrification or conservation currently exists. (b) Electricity system demand. Increased efficiency in the building and industry sector can reduce California’s 2050 demand from the frozen efficiency case by 35%, and conservation can provide a further 16% electricity demand reduction. Increases in electricity demand stem from electrification of building heat, industry process heating, and vehicles. 24 000 GWh of additional demand based on analysis of increased (figure 1(b)), adding 32 000 GWh to the electricity end-use applications by industry sector and the availability load in 2050. of multiple electric-based process heating technologies. In addition to minimizing fossil fuel demand from the Residential and commercial space and water heating are State’s non-electricity energy supply, increased efficiency of fully electrified by 2050 (figure 1(b)) through a transition to electrical devices in all buildings is also assumed [19, 20]. high-efficiency heat pump technology. Without increased efficiency, much higher electricity demand Hourly load profiles for electricity demand from space and greater capacity of generation supply would be required. For reference, we consider a ‘frozen efficiency’ case where and water heating in buildings are developed based on efficiency levels are held at present day levels. historical heating load profiles, disaggregated by California climate zone, and scaled up to displace all remaining A bottom-up stock model is used to simulate efficiency GHG-intensive heating demands within buildings (figure 3). improvements in residential and commercial buildings [21, Electricity demand from water and space heating is greatly 22], achieving 38% electricity savings in 2050 relative to 3 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 2. Primary energy evolution in California from 2011 and 2050 for the compliant case depicted in figure 1. Note the dramatic shift in energy sources over time, with the percentage of primary energy for electricity doubling present levels by 2050. Petroleum-based liquid fuel is sharply reduced and the fossil fuel fraction of primary energy drops from 90% in 2011 to 44% in 2050. Primary energy for combustible fuels (petroleum, natural gas, coal, biomass, biogas) is defined as the higher heating value of the fuel prior to combustion, whereas primary energy for non-combustible fuels (hydroelectric, nuclear, geothermal, solar, wind) is defined as the heat content of net electricity generated. Net energy from imports and exports of electricity to and from California are calculated hourly using the SWITCH model as the fraction imported multiplied by the out-of-State electricity generation minus the fraction exported multiplied by the in-State electricity generation. the frozen efficiency case. For existing buildings, 100% of New plants will replace a large fraction of electricity technically feasible opportunities to improve efficiency on a generation in today’s power system by 2050, representing retrofit or ‘replace on burnout’ basis are applied to eligible an opportunity to transform the State’s current mix of power buildings by 2050 (supplementary material available at plants and increase the reliance on low-GHG power sources. stacks.iop.org/ERL/8/014038/mmedia). Energy savings from Large-scale integrated planning using suitable policies and new construction is similar to California Public Utilities investments is needed to minimize the cost of this transition. Commission initiatives for Zero Net Energy New Construc- In order to leverage the spatial and temporal synergies tion buildings [23]: 100% of new residential (commercial) among two of the most promising low-GHG generation buildings achieve at least 35% (30%) electricity savings by technologies (solar and wind), careful combinations of 2025 (2030) compared to 2005 efficiency standards. investments are needed to ensure low-GHG, low-cost, and Load profiles are synthesized from the mix of end-use reliable electric power. High-quality renewable resources are demands and technologies using a load profile database for unevenly distributed both spatially and temporally throughout both efficiency and building electrification [24]. Efficiency western North America [25]. It is therefore essential to load profiles for 8760 h yr in 14 California climate zones include the entire western North American synchronous and 20 end-uses are synthesized and provided as inputs to the interconnect—the geographic area of the Western Electricity electric sector model. Coordinating Council (WECC)—in an analysis of future Efficiency savings in 2050 are dominated by a California low-GHG electricity supply. small number of end-uses. For residential buildings, 63% The SWITCH electric power system planning model of cumulative efficiency savings come from lighting, is used to explore future electricity scenarios with a refrigeration, and central air-conditioning. For commercial WECC-wide cap on power sector GHG emissions, reaching buildings, just three uses contribute 81% of the savings: 80% below the 1990 level in 2050. Power sector GHG interior lighting, cooling, and refrigeration. allowances are implicitly assumed to be tradable across WECC. The version of SWITCH used in this study minimizes the cost of producing and delivering electricity from present 4. High-resolution electricity sector modeling day until 2050 using a combination of existing grid assets and GHG reduction from electrification is predicated on a shift to new generation, transmission, and storage capacity. low-GHG electricity. Despite aggressive efficiency measures, Shifting vehicle and heating demand toward electricity overall electricity demand in the compliant case is only 10% would drastically change seasonal and diurnal load profiles lower than the frozen case due to increases from transportation (figure 3). By 2050, the load profile exhibits a strong morning peak in winter due to added demand from water heating, and heating. As a result, drastic but technically feasible shifts in the electric power system appear necessary to decarbonize as well as a new evening peak throughout the year due California’s energy system. to electric vehicle charging. In addition, air conditioning 4 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Table 1. Summary table of energy demands and emission intensities for buildings, industry, and transportation sectors for 2011 and four 2050 cases. State population is assumed to increase 60% to 59.5 million residents in 2050 from 37.7 million residents currently. Energy Relative emissions intensity relative to current (2011 D 1) 2050 compliant 2050 compliant (increased (increased 2050 increased efficiency, 2050 increased efficiency, efficiency, low-GHG efficiency, low-GHG low-GHG electricity, low-GHG electricity, 2050 electricity, electrification, 2050 2050 electricity, electrification, 2050 frozen increased electrification, biofuels, frozen increased electrification, biofuels, Energy supply Units 2011 efficiency efficiency biofuels conservation) efficiency efficiency biofuels conservation) Buildings Liquid, solid Tbtu 52 77 54 17 15 1 1 1 1 fuels Gaseous fuel Tbtu 710 1 052 735 227 209 1 1 1 1 Sum Tbtu 762 1 129 789 244 224 Change 48% 30% 69% 8% Electricity GWh 176 500 288 200 178 800 213 400 196 500 1 1 0.12 0.12 Change 63% 38% 19% 8% Industry Liquid, solid Tbtu 496 611 276 130 94 1 1 0.86 0.86 fuels Gaseous fuel Tbtu 1 039 1 255 604 322 232 1 1 0.94 0.94 Sum Tbtu 1 535 1 866 880 452 325 Change 22% 53% 49% 28% Electricity GWh 47 200 81 100 58 400 91 900 66 200 1 1 0.12 0.12 Change 72% 28% 57% 28% Transportation Liquid, solid Bgge 21.4 38.5 20.2 10.6 8.8 1 1 0.50 0.50 fuels Change 80% 48% 48% 17% Electricity GWh 0 0 0 97 000 80 900 1 1 0.12 0.12 Change 17% Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 3. (a) Drastic shifts in load profile are seen from the implementation of efficiency (‘post efficiency’ scenario) and subsequent addition of loads from electric vehicles and heating. The compliant case (‘Base Case’) represents the load profile used as an input to the SWITCH model. One peak and one median demand day per season are shown in the figure for clarity, though the SWITCH model uses six days per season for each decadal time step. (b) WECC-wide electricity generation in 2050 as dispatched by SWITCH for the frozen efficiency load profile (c) WECC-wide electricity generation in 2050 as dispatched by SWITCH for the compliant case from figures 1(b) and 3(a). Note the shift from solar to wind power as the amount of efficiency and vehicle and heating electrification is increased from the frozen efficiency load profile. loads in summer afternoons remain prominent even after new can cost-effectively meet aggressive GHG reduction targets, efficiency measures are introduced, producing an electricity even with drastic changes in load profile shape due to system with high demand periods in both summer and winter. efficiency and large vehicle and heating loads (supplementary We model this load profile separately for each of 50 areas material available at stacks.iop.org/ERL/8/014038/mmedia). within WECC for six hours of each of 24 representative The scenarios explored in this study show that variable days in the decades 2020–2050. Both peak and median renewable resources (wind and solar) could economically load days from each month are represented to ensure that contribute as little as one-third or as much as three-fifths SWITCH plans for average and peak conditions across an of generated power within WECC by 2050. Despite their entire year. In each modeled hour, demand must be met by variability, both wind and solar technologies appear poised to the optimization, as well as capacity and operational reserve supply large amounts of inexpensive, low-GHG electricity to margin constraints to ensure system reliability. Results from the WECC power system of the future. investment optimizations are validated using a full year of The optimal fractions of wind and solar deployment are hourly load and variable renewable resource data. a function of the temporal characteristics of the load profile, with increasing vehicle and heating electrification favoring 5. Many cost-effective electricity generation options wind over solar power (figure 3). As nighttime heating and Using the SWITCH model, we find that the WECC electricity electric vehicle loads increase, the energy and capacity value system in 2050 has a diverse set of generation options that of wind power increases relative to that of solar. Increasing 6 Environ. Res. Lett. 8 (2013) 014038 M Wei et al Figure 4. Average 2050 electricity generation by fuel category, and average 2050 power cost (in $2007 per MWh) for ten electricity scenarios in which WECC-wide power sector emissions are capped at 80% below 1990 levels. The biomass solid CCS scenario includes further GHG reductions. The frozen, no carbon cap scenario does not include a cap on GHG emissions. The compliant case (‘Base Case’) is the starting point on which other sensitivity scenarios are based. Information on specific scenarios can be found in the supplementary material (available at stacks.iop.org/ERL/8/014038/mmedia). The average power cost varies by less than $20 per MWh across GHG-capped scenarios, indicating that many low-cost, low-GHG options exist for the power sector. demand flexibility could incentivize either wind or solar cost and generator availability scenarios. While this result power, depending on their relative delivered costs. is in part dependent on technological improvement driving Using operating reserve requirements and large balancing declining capital costs, sensitivity analyses show that three areas similar to those evaluated in the Western Wind and future supply options with the most uncertain costs—solar Solar Integration Study [26], we find that the majority of photovoltaics, nuclear, and fossil/CCS—are not individually spinning reserves in WECC can be provided by hydroelectric essential to keep the cost of electricity low. In all scenarios, power and storage technologies, with the balance provided total power system cost increases roughly in proportion to by gas-fired technologies. Sub-hourly load balancing does not load, so while increasing demand adds to total expenditures, appear to be a major limitation for achieving deep emissions the average cost per MWh is stable through 2050. Relative to reduction in a future electricity grid with up to 60% of energy a scenario in which no cap on GHG emissions is enforced, from variable renewable generation. achieving 80% GHG reductions in the power sector raises the Nuclear power and fossil fuel generation with CO cost of power by 18%–42%. The tight range of power system capture and sequestration (fossil/CCS) may be attractive costs found amongst a variety of scenarios (figure 4) indicates low-GHG baseload technologies, but neither is essential to that GHG reduction via electrification is a robust strategy, as meeting GHG targets (figure 4). With the costs assumed in the risk of power cost overruns is reduced by the availability this study, generating electricity from fossil/CCS can lower of a portfolio of technologies. the cost of power while meeting emissions targets. Installation of new nuclear power is found to be a backstop against rising 6. Discussion—the need for integrated planning and power costs, but is not cost-effective given our base cost policy assumptions. Greater fractions of energy from variable renewable Long-range planning can ensure that current policies and resources are found to increase the magnitude of transmission pathways are consistent with long-term goals. Policies that and storage deployment (figures S69 and S71 available focus on improving natural gas heating or conventional at stacks.iop.org/ERL/8/014038/mmedia). Power systems in internal combustion engine efficiency without transitioning this study that generate less than half of their electricity away from fossil fuel may be appropriate for the short from variable renewable resources are not found to need term, but are not sufficient for meeting long-term GHG drastic expansion of the transmission system nor large-scale targets. Similarly, the electrification of heating will only be deployment of electric energy storage. However, as the an effective measure for meeting an 80% reduction goal fraction of electricity from variable renewable resources if the electricity supply has a near zero-GHG intensity. exceeds fifty per cent, increasing amounts of transmission The interaction among different sectors and various GHG- and storage are installed in order to spatially and temporally reduction pathways should continue to be an active area of move electricity from the point of generation to the point of research and optimization. consumption. The average cost per MWh of electricity stays relatively Technology does not appear to be the limiting factor for constant between present day and 2050 across a range of the State to meet its economy-wide 2050 GHG emissions 7 Environ. Res. Lett. 8 (2013) 014038 M Wei et al target, though this conclusion is predicated upon ample industry) with piecewise additive scenarios for energy low-GHG biomass supplies (with little or no associated demand and energy supply. First, energy efficiency is indirect land use impacts), steady technological development applied across sectors, then clean electricity is added, and cost reduction of existing technologies, and more followed by electrification, low carbon biofuels, and then modest economic growth than assumed in other studies [5, energy conservation. Electricity and fuel supply mixes 6]. Much of the technology already exists for increased were developed to meet overall demand subject to biofuel electrification and building efficiency, but may need policy availability and GHG constraints for electricity. GHG support to achieve cost-effective production at scale and emissions were calculated for each scenario based on more importantly, to induce widespread adoption (tables S1 overall energy demands and carbon intensity of energy and S2 available at stacks.iop.org/ERL/8/014038/mmedia). supplies. Assumptions for the boundaries and scope of Plug-in electric vehicles are being rapidly developed by GHG emission treatment are discussed in the supplementary the automotive sector, but there is less activity in other material (available at stacks.iop.org/ERL/8/014038/mmedia). transportation sectors. Availability of biomass and low-GHG Energy demand for a frozen efficiency case was first process development are pivotal for reducing fuel-use GHG estimated as a reference case with growth rates informed emissions. by historical trends and other studies. An energy efficiency In addition to technological solutions, substantial case was then developed assuming that technical potential reductions are also possible from conservation measures [27]. levels of efficiency are achieved across all three sectors. Preliminary modeling of these GHG-saving measures was A low-GHG electricity supply was added to this scenario conducted based on historical trends in non-energy behaviors (energy supply modeling is described below). Fuel-switching including public health, safety, and diet. By 2050, as much as was introduced by assuming wide spread electrification from 16% of GHG emissions could be conserved by measures such gasoline-based internal combustion engines to electrified as reductions in vehicle-miles traveled, eco-driving, increased or partially electrified passenger vehicles and from largely energy conservation, improved diets, waste reduction, and natural gas based heating processes to electrified heating increased recycling (section 9, supplementary material in buildings and industry. Further carbon reduction was available at stacks.iop.org/ERL/8/014038/mmedia). Human achieved by assuming technical potential availability of liquid and social factors should be a topic for further research, biofuels and finally by assuming conservation measures are as they are directly coupled with public policy, technology aggressively adopted. deployment, and market development. Energy demand was disaggregated into building, trans- Expansion of California’s policy framework is needed to portation, and industry sectors for California. Estimates enable energy system changes suggested herein. Aggressive utilized a median population and economic growth forecast codes and standards will be required to meet building, vehicle, based on State and California Energy Commission (CEC) esti- and industry efficiency targets. While efficiency is already a mates, respectively. Building demands for electricity and fuel focus for the State, implementation and adoption of additional (e.g., natural gas for heating) were developed for residential efficiency measures is critical, especially for building retrofits. and commercial buildings as described in the supplementary Policies are currently in place for both vehicle electrification material (available at stacks.iop.org/ERL/8/014038/mmedia) and low-GHG biofuels, but will need extension and expansion and further disaggregated into single/multi-family units and to meet the 2050 climate goal. Multiple barriers exist for new/existing buildings. Stock turnover analysis was done building electrification, and policy development is urgently for a comprehensive set of end-use demands. Commercial needed to ensure the transition to electrified heating. An 80% buildings demand estimates utilized historical trends of reduction in electricity sector emissions can be ensured with energy demand per square foot of space by building type. a continuation and expansion of aggressive renewable energy Electricity demand for the rest of the Western Electricity and/or GHG targets in the future. Coordination Council geographic region was estimated from a Meeting the State’s 2050 GHG target is found to synthesis of US Energy Information Administration data and be feasible but requires a portfolio of measures and a regional utility forecasts. commitment to integrating and coordinating policies in the Transportation demand estimates utilized vehicle stock electricity, buildings, transportation, and industrial sectors. modeling for passenger vehicles and aviation with projections The GHG reduction measures put forward here include an increase in the efficiency of energy use for all sectors, a for other transportation modes consistent with State or drastic decrease in the GHG intensity of electricity and liquid federal models. Stock modeling assumptions of vehicles fuels, and a substitution of end-use fuel consumption for per capita, vehicle-miles travelled (VMT) per vehicle, and electricity. Behavioral factors may also be able to play an market penetrations by vehicle drivetrain (internal combustion important role in GHG emission reduction. Long-term policy engines, hybrid electric vehicles, plug-in hybrid vehicles, and support is found to be a key missing element for the successful battery electric vehicles) are described in the supplementary attainment of the 2050 GHG target in California. material (available at stacks.iop.org/ERL/8/014038/mmedia). Industry demand estimates employed sector-based (oil and gas, food and beverage, etc) economic growth projections 7. Materials and methods from the CEC. Future electricity and fuel demands were projected for The energy efficiency scenario utilized technical potential three economic sectors (buildings, transportation, and estimates for each sector. The building sector employed 8 Environ. Res. Lett. 8 (2013) 014038 M Wei et al a list of over 200 unique efficiency measures while References the transportation sector adopted fuel efficiency potential [1] Commission of European Communities 2007 Limiting Global from existing national and State studies. Industry technical Climate Change to 2 Degrees Celsius: The Way Ahead for potential estimates were based on CEC reports disaggregated 2020 and Beyond (available at http://eur-lex.europa.eu/ by industry sector and end-use (process heating, boiler-based LexUriServ/site/en/com/2007/com2007 0002en01.pdf, systems, motor systems, heating, ventilation, air-conditioning, accessed 1 July 12) etc). [2] California Institute for Energy and Environment 2012 Electrification projections are based on stock modeling California Vulnerability and Adaption Study (available at http://uc-ciee.org/climate-change/california-vulnerability- for building water and space heating and for passenger and-adaptation-study, accessed 1 August 12) vehicles assuming aggressive transition to electricity-based [3] Jackson S 2009 Parallel pursuit of near-term and long-term heating systems in buildings starting in 2015 and to alternative climate mitigation Science 326 526–7 passenger vehicles in transportation, respectively, with market [4] California Environmental Protection Agency Air Resources penetration assumptions described in the supplementary Board 2012 California Greenhouse Gas Inventory for 1990 (available at www.arb.ca.gov/cc/inventory/pubs/reports/ material (available at stacks.iop.org/ERL/8/014038/mmedia). appendix a1 inventory ipcc sum 1990.pdf, accessed The carbon savings potential for energy conservation 10 June 12) was estimated using a simple adoption rate model of energy [5] Williams J H, DeBenedictis A, Ghanadan R, Mahone A, saving actions. From a database of historical non-energy Moore J, Morrow W R III, Price S and Torn M S 2012 The actions, long-term adoption rates were estimated for a set technology path to deep greenhouse gas emissions cuts by 2050: the pivotal role of electricity Science 335 53–9 of conservation actions in home energy usage and passenger [6] California Council on Science and Technology 2011 vehicle mile reduction, as well as a number of other measures California’s Energy Future—The View to 2050 (available at in diet, recycling, and consumption. Carbon savings as http://ccst.us/publications/2011/2011energy.pdf, accessed a function of time were estimated by calculating carbon 1 July 12) intensities for electricity (CO =kWh) and transportation [7] Long J C S 2011 Piecemeal cuts won’t add up to radical reductions Nature 478 429 (CO =VMT). [8] European Climate Foundation 2010 ROADMAP 2050: A Low-GHG electricity modeling utilized a high-resolution Practical Guide to a Prosperous, Low-GHG Europe variable renewable resource capacity planning model (available at www.roadmap2050.eu, accessed 1 July 12) (SWITCH) of the interconnected Western North American [9] Yang C, Ogden J M, Sperling D and Hwang R 2011 grid. SWITCH used spatially resolved, time-synchronized California’s Energy Future: Transportation Energy Use in California (Sacramento, CA: California Council on Science hourly solar, wind, and demand data to explore future low and Technology) (available at http://ccst.us/publications/ carbon electricity scenarios. Optimizations minimized the 2011/2011transportation.pdf, accessed 1 July 2012) cost of power between present day and 2050 while subject [10] Jacobson M Z and Delucchi M A 2011 Providing all global to reliability and policy constraints. Carbon emissions were energy with wind, water, and solar power, part I: constrained to reach 80% below 1990 levels in the year 2050. technologies, energy resources, quantities and areas of infrastructure, and materials Energy Policy 39 1154–69 Biofuel supply estimates were made with all biomass [11] Fripp M 2008 Optimal investment in wind and solar power in directed to liquid biofuels and resultant biofuel assumed to California PhD Dissertation University of California replace oil-based liquid fuel. Biomass and biofuel availability Energy and Resources Group projections utilized technical potential assumptions for in- [12] Nelson J, Johnston J, Mileva A, Matthias Fripp M, Hoffman I, State biomass supply, biomass supply mix, biofuel yield, and Petros-Good A, Blanco C and Kammen D M 2012 life-cycle carbon emission associated with biofuel production. High-resolution modeling of the western North American power system demonstrates low-cost and low-GHG futures Biofuel production was assumed to replace gasoline in Energy Policy 43 436–47 the transportation sector. Sources for biomass materials [13] Fripp M 2012 SWITCH: a planning tool for power systems availability include earlier reports from Oak Ridge National with large shares of intermittent renewable energy Environ. Laboratory, the University of California, Berkeley, and the Sci. Technol. 46 6371–8 University of California, Davis. [14] State of California 2013 ZEV Action Plan A Roadmap Toward 1.5 Million Zero-Emission Vehicles on California All methods and key assumptions are described more Roadways by 2025 First Edition (Governor’s Interagency fully in the supplementary material available online at (stacks. Working Group on Zero-Emission Vehicles, Office of iop.org/ERL/8/014038/mmedia) . Governor Edmund G Brown Jr) (available at http://opr.ca. gov/docs/Governor’s Office ZEV Action Plan (02-13). pdf, accessed 19 February 13) Acknowledgments [15] Schmidt P S 1984 Electricity and Industrial Productivity, A Technical and Economic Perspective (New York, NY: We thank the California Energy Commission for support. This Pergamon) paper reflects the views of the authors and does not necessarily [16] Electric Power Research Institute 2009 The Potential to reflect the view of the California Energy Commission or the Reduce CO Emissions by Expanding End-Use Applications of Electricity EPRI Report 1018871 State of California. DMK thanks the Class of 1935 of the [17] US Department of Energy 2007 Improving Process Heating University of California, Berkeley, and the Karsten Family System Performance: A Sourcebook for Industry 2nd edn Foundation. (Golden, CO: US Department of Energy Industrial None of the authors have a conflict of interest for this Technologies Program and Industrial Heating Equipment work. Association) 9 Environ. Res. Lett. 8 (2013) 014038 M Wei et al [18] Greenblatt J, Wei M and McMahon J 2012 California’s [23] California Public Utilities Commission 2008 California Long Energy Future: Buildings and Industrial Energy Efficiency Term Energy Efficiency Strategic Plan (available at www. (Sacramento, CA: California Council on Science and cpuc.ca.gov/NR/rdonlyres/D4321448-208C-48F9-9F62- Technology) (available at http://ccst.us/publications/2011/ 1BBB14A8D717/0/EEStrategicPlan.pdf, accessed 1 July CEF%20index.php, accessed 15 February 2013) 2012) [19] Masanet E et al 2013 Estimation of Long-Term [24] California Energy Commission 2006 California Commercial Energy-Efficiency Potentials for California Buildings and Building End-Use Survey (Report No CEC-400-2006-005) Industry (Public Interest Energy Research Program Report, (Sacramento, CA: California Energy Commission) Draft Report) (Sacramento, CA: California Energy [25] Hand M M, Baldwin S, DeMeo E, Reilly J M, Mai T, Arent D, Commission) Porro G, Meshek M and Sandor D (ed) 2012 Renewable [20] Rufo M W and North A S 2007 Assessment of Long-Term Electricity Futures Study (Entire Report) (Report No Electric Energy Efficiency Potential in California’s NREL/TP-6A20-52409) (Golden, CO: National Renewable Residential Sector (PIER Energy-Related Environmental Energy Laboratory) 4 volumes Research Report Report No CEC-500-2007-002) [26] National Renewable Energy Laboratory 2010 Western Wind (Sacramento, CA: California Energy Commission) and Solar Integration Study (Report No [21] Itron, Inc. 2008 California Energy Efficiency Potential Study NREL/SR-550-47434) (Golden, CO: National Renewable CALMAC Study ID: PGE0264.01 (available at www. Energy Laboratory) calmac.org/startDownload.asp?Name=PGE0264 Final [27] Jones C M and Kammen D M 2011 Quantifying carbon Report.pdf&Size=5406KB, accessed 1 July 2012) footprint reduction opportunities for US households and [22] Palmgren C, Stevens N, Goldberg M, Barnes R and communities Environ. Sci. Technol. 45 4088–95 Rothkin K 2010 2009 California Residential Appliance [28] Sullivan D, Wang D and Bennett D 2011 Essential to energy Saturation Study (Report No CEC-200-2010-004) efficiency, but easy to explain: frequently asked questions (Sacramento, CA: California Energy Commission) about decoupling Electr. J. 24 56–70

Journal

Environmental Research LettersIOP Publishing

Published: Mar 1, 2013

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