Providing all global energy with wind, water and solar
Part 1: Technologies, energy resources, quantities and areas of infrastructure, and materials
Mark Z. Jacobson, Mark A. Delucchi
Climate change, pollution, and energy insecurity are among the greatest problems of our time. Addressing them requires major changes in our energy infrastructure. Here, we analyze the feasibility of providing worldwide energy for all purposes (electric power, transportation, heating/cooling, etc.) from wind, water, and sunlight (WWS). In Part I, we discuss WWS energy system characteristics, current and future energy demand, availability of WWS resources, numbers of WWS devices, and area and material requirements. In Part II, we address variability, economics, and policy of WWS energy. We estimate that 3,800,000 5 MW wind turbines, 49,000 300 MW concentrated solar plants, 40,000 300 MW solar PV power plants, 1.7 billion 3 kW rooftop PV systems, 5350 100 MW geothermal power plants, 270 new 1300 MW hydroelectric power plants, 720,000 0.75 MW wave devices, and 490,000 1 MW tidal turbines can power a 2030 WWS world that uses electricity and electrolytic hydrogen for all purposes. Such a WWS infrastructure reduces world power demand by 30% and requires only 0.41% and 0.59% more of the world’s land for footprint and spacing, respectively. We suggest producing all new energy with WWS by 2030 and replacing the pre-existing energy by 2050. Barriers to the plan are primarily social and political, not technological or economic. The energy cost in a WWS world should be similar to that today.
A solution to the problems of climate change, air pollution, water pollution, and energy insecurity requires a large-scale conversion to clean, perpetual, and reliable energy at low cost together with an increase in energy efficiency. Over the past decade, a number of studies have proposed large-scale renewable energy plans. Jacobson and Masters (2001) suggested that the U.S. could satisfy its Kyoto Protocol requirement for reducing carbon dioxide emissions by replacing 60% of its coal generation with 214,000–236,000 wind turbines rated at 1.5 MW (million watts). Also in 2001, Czisch (2006) suggested that a totally renewable electricity supply system, with intercontinental transmission lines linking dispersed wind sites with hydropower backup, could supply Europe, North Africa, and East Asia at total costs per kWh comparable with the costs of the current system. Hoffert et al. (2002) suggested a portfolio of solutions for stabilizing atmospheric CO2, including increasing the use of renewable energy and nuclear energy, decarbonizing fossil fuels and sequestering carbon, and improving energy efficiency. Pacala and Socolow (2004) suggested a similar portfolio, but expanded it to include reductions in deforestation and conservation tillage and greater use of hydrogen in vehicles.
More recently, Fthenakis et al. (2009) analyzed the technical, geographical, and economic feasibility for solar energy to supply the energy needs of the U.S. and concluded (p. 397) that ‘‘it is clearly feasible to replace the present fossil fuel energy infrastructure in the U.S. with solar power and other renewables, and reduce CO2 emissions to a level commensurate with the most aggressive climate-change goals’’. Jacobson (2009) evaluated several longterm energy systems according to environmental and other criteria, and found WWS systems to be superior to nuclear, fossil-fuel, and biofuel systems (see further discussion in Section 2). He proposed to address the hourly and seasonal variability of WWS power by interconnecting geographically disperse renewable energy sources to smooth out loads, using hydroelectric power to fill in gaps in supply. He also proposed using battery-electric vehicles (BEVs) together with utility controls of electricity dispatch to them through smart meters, and storing electricity in hydrogen or solar-thermal storage media. Cleetus et al. (2009) subsequently presented a ‘‘blueprint’’ for a clean-energy economy to reduce CO2-equivalent GHG emissions in the U.S. by 56% compared with the 2005 levels. That study featured an economy-wide CO2 cap-and-trade program and policies to increase energy efficiency and the use of renewable energy in industry, buildings, electricity, and transportation. Sovacool and Watts (2009) suggested that a completely renewable electricity sector for New Zealand and the United States is feasible.
In Jacobson and Delucchi (2009), we outlined a large-scale plan to power the world for all purposes with WWS (no biofuels, nuclear power, or coal with carbon capture). The study found that it was technically feasible to power the world with WWS by 2030 but such a conversion would almost certainly take longer due to the difficulty in implementing all necessary policies by then. However, we suggested, and this study reinforces, the concept that all new energy could be supplied by WWS by 2030 and all existing energy could be converted to WWS by 2050. The analysis presented here is an extension of that work.
Table 1 compares and summarizes several other recent largescale plans. While all plans are ambitious, forward thinking, and detailed, they differ from our plan, in that they are for limited world regions and none relies completely on WWS. However, some come close in the electric power sector, relying on only small amounts of non-WWS energy in the form of biomass for electric power production. Those studies, however, address only electricity and/or transport, but not heating/cooling.
More well known to the public than the scientific studies, perhaps, are the ‘‘Repower America’’ plan of former Vice-President and Nobel-Peace Prize winner Al Gore, and a similar proposal by businessman T. Boone Pickens. Mr. Gore’s proposal calls for improvements in energy efficiency, expansion of renewable energy generation, modernization of the transmission grid, and the conversion of motor vehicles to electric power. The ultimate (and ambitious) goal is to provide America ‘‘with 100% clean electricity within 10 years,’’ which Mr. Gore proposes to achieve by increasing the use of wind and concentrated solar and improving energy efficiency (Alliance for Climate Protection, 2009). In Gore’s plan, solar PV, geothermal, and biomass electricity would grow only modestly, and nuclear power and hydroelectricity would not grow. Mr. Pickens’ plan is to obtain up to 22% of the U.S. electricity from wind, add solar capacity to that, improve the electric grid, increase energy efficiency, and use natural gas instead of oil as a transitional fuel (Pickens, 2009).
There is little doubt that the large-scale use of renewable energy envisaged in these plans and studies would greatly mitigate or eliminate a wide range of environmental and human health impacts of energy use (e.g., Jacobson, 2009; Sovacool and Sovacool, 2009; Colby et al., 2009; Weisser, 2007; Fthenakis and Kim, 2007). But, is a large-scale transformation of the world’s energy systems feasible? In this paper and in Part II, we address this question by examining the characteristics and benefits of wind, water, and solar (WWS)-energy systems, the availability of WWS resources, supplies of critical materials, methods of addressing the variability of WWS energy to ensure that power supply reliably matches demand, the economics of WWS generation and transmission, the economics of the use ofWWS power in transportation, and policy issues. Although we recognize that a comprehensive plan to address global environmental problems must also address other sectors, including agriculture (Horrigan et al., 2002; Wall and Smit, 2005) and forestry (Niles et al., 2002), we do not address those issues here.
2. Clean, low-risk, sustainable energy systems
2.1. Evaluation of long-term energy systems: why we choose WWS power
Because climate change (particularly loss of the Arctic sea ice cap), air pollution, and energy insecurity are the current and growing problems, but it takes several decades for new technologies to become fully adopted, we consider only options that have been demonstrated in at least pilot projects and that can be scaled up as part of a global energy system without further major technology development. We avoid options that require substantial further technological development and that will not be ready to begin the scale-up process for several decades. Note that we select technologies based on the state of development of the technology only rather than whether industrial capacity is currently ramped up to produce the technologies on a massive scale or whether society is motivated to change to the technologies. In this paper and in Part II, we do consider the feasibility of implementing the chosen technologies based on estimated costs, necessary policies, and available materials as well as other factors.
In order to ensure that our energy system remains clean even with large increases in population and economic activity in the long run, we consider only those technologies that have essentially zero emissions of greenhouse gases and air pollutants per unit of output over the whole ‘‘lifecycle’’ of the system. Similarly, we consider only those technologies that have low impacts on wildlife, water pollution, and land, do not have significant waste-disposal or terrorism risks associated with them, and are based on primary resources that are indefinitely renewable or recyclable.
The previous work by Jacobson (2009) indicates that WWS power satisfies all of these criteria. He ranked several long-term energy systems with respect to their impacts on global warming, air pollution, water supply, land use, wildlife, thermal pollution, water–chemical pollution, and nuclear weapons proliferation. The ranking of electricity options, starting with the highest, included: wind power, concentrated solar, geothermal, tidal, solar photovoltaic, wave, and hydroelectric power, all of which are powered by wind, water, or sunlight (WWS). He also found that the use of BEVs and hydrogen fuel-cell vehicles (HFCVs) powered by the WWS options would largely eliminate pollution from the transportation sector. Here, we consider these technologies and other existing technologies for the heating/cooling sectors, discussed in Section 2. Although other clean WWS electric power sources, such as ocean or river current power, could be deployed in the short term, these are
not examined here simply because we could not cover every technology. Nevertheless, we do cover related although slightly different power sources (e.g., wave, tidal, and hydroelectric power).
Finally, Jacobson (2009) concluded that coal with carbon capture, corn ethanol, cellulosic ethanol, and nuclear power were all moderately or significantly worse than WWS options with respect to environmental and land use impacts. Similarly, here we do not consider any combustion sources, such as coal with carbon capture, corn ethanol, cellulosic ethanol, soy biodiesel, algae biodiesel, biomass for electricity, other biofuels, or natural gas, because none of these technologies can reduce GHG and air-pollutant emissions to near zero, and all can have significant problems in terms of land use, water use, or resource availability (See Delucchi (2010) for a review of land-use, climate-change, and
water-use impacts of biofuels.) For example, even the most climate-friendly and ecologically acceptable sources of ethanol, such as unmanaged, mixed grasses restored to their native (nonagricultural) habitat (Tilman et al., 2006), will cause air pollution mortality on the same order as gasoline (Jacobson, 2007; Anderson, 2009; Ginnebaugh et al., 2010). The use of carbon capture and sequestration (CCS) can reduce CO2 emissions from the stacks of coal power plants by 85–90% or more, but it has no effect on CO2 emissions due to the mining and transport of coal; in fact it will increase such emissions and of air pollutants per unit of net delivered power and will increase all ecological, land-use, air-pollution, and water-pollution impacts from coal mining, transport, and processing, because the CCS system requires 25% more energy, thus 25% more coal combustion, than does a system without CCS (IPCC, 2005).
For several reasons we do not consider nuclear energy (conventional fission, breeder reactors, or fusion) as a long-term global energy source. First, the growth of nuclear energy has historically increased the ability of nations to obtain or enrich uranium for nuclear weapons (Ullom, 1994), and a large-scale worldwide increase in nuclear energy facilities would exacerbate this problem, putting the world at greater risk of a nuclear war or terrorism catastrophe (Kessides, 2010; Feiveson, 2009; Miller and Sagan, 2009; Macfarlane and Miller, 2007; Harding, 2007). The historic link between energy facilities and weapons is evidenced by the development or attempted development of weapons capabilities secretly in nuclear energy facilities in Pakistan, India (Federation of American Scientists, 2010), Iraq (prior to 1981), Iran (e.g., Adamantiades and Kessides, 2009, p. 16), and to some extent North Korea. Feiveson (2009) writes that ‘‘it is well understood that one of the factors leading several countries now without nuclear power programs to express interest in nuclear power is the foundation that such programs could give them to develop weapons’’ (p. 65). Kessides (2010) asserts, ‘‘a robust global expansion of civilian nuclear power will significantly increase proliferation risks unless the current non-proliferation regime is substantially strengthened by technical and institutional measures and its international safeguards system adequately meets the new challenges associated with a geographic spread and an increase in the number of nuclear facilities’’ (p. 3860). Similarly, Miller and Sagan (2009) write, ‘‘it seems almost certain that some new entrants to nuclear power will emerge in the coming decades and that the organizational and political challenges to ensure the safe and secure spread of nuclear technology into the developing world will be substantial and potentially grave’’ (p. 12).
If the world were converted to electricity and electrolytic hydrogen by 2030, the 11.5 TW in resulting power demand would require 15,800 850 MW nuclear power plants, or one installed every day for the next 43 years. Even if only 5% of these were installed, that would double the current installations of nuclear power worldwide. Many more countries would possess nuclear facilities, increasing the likelihood that these countries would use the facilities to hide the development of nuclear weapons as has occurred historically.
Second, nuclear energy results in 9–25 times more carbon emissions than wind energy, in part due to emissions from uranium refining and transport and reactor construction (e.g., Lenzen, 2008; Sovacool, 2008), in part due to the longer time required to site, permit, and construct a nuclear plant compared with a wind farm (resulting in greater emissions from the fossil-fuel electricity sector during this period; Jacobson, 2009), and in part due to the greater loss of soil carbon due to the greater loss in vegetation resulting from covering the ground with nuclear facilities relative to wind turbine towers, which cover little ground. Although recent construction times worldwide are shorter than the 9-year median construction times in the U.S. since 1970 (Koomey and Hultman, 2007), they still averaged 6.5 years worldwide in 2007 (Ramana,
2009), and this time must be added to the site permit time (3 years in the U.S.) and construction permit and issue time (3 years). The overall historic and present range of nuclear planning-to-operation times for new nuclear plants has been 11–19 years, compared with an average of 2–5 years for wind and solar installations (Jacobson, 2009). Feiveson (2009) observes that ‘‘because wind turbines can be installed much faster than could nuclear, the cumulative greenhouse gas savings per capital invested appear likely to be greater for wind’’ (p. 67). The long time required between planning and operation of a nuclear power plant poses a significant risk to the Arctic sea ice. Sea ice records indicate a 32% loss in the August 2010 sea ice area relative to the 1979–2008 mean (Cryosphere Today, 2010). Such rapid loss indicates that solutions to global warming must be implemented quickly. Technologies with long lead times will allow the high-albedo Arctic ice to disappear, triggering more rapid positive feedbacks to warmer temperatures by uncovering the low-albedo ocean below.
Third, conventional nuclear fission relies on finite stores of uranium that a large-scale nuclear program with a ‘‘once through’’ fuel cycle would exhaust in roughly a century (e.g., Macfarlane and Miller, 2007; Adamantiades and Kessides, 2009). In addition, accidents at nuclear power plants have been either catastrophic (Chernobyl) or damaging (Three-Mile Island), and although the nuclear industry has improved the safety and performance of reactors, and has proposed new (but generally untested) ‘‘inherently’’ safe reactor designs (Piera, 2010; Penner et al., 2008; Adamantiades and Kessides, 2009; Mourogov et al., 2002; Mourogov, 2000), there is no guarantee that the reactors will be designed, built, and operated correctly. For example, Pacific Gas and Electric Company had to redo some modifications it made to its Diablo Canyon nuclear power plant after the original work was done backwards (Energy Net, 2010), and French nuclear regulators recently told the firm Areva to correct a safety design flaw in its latest-generation reactor (Nuclear Power Daily, 2009). Further, catastrophic scenarios involving terrorist attacks are still conceivable (Feiveson, 2009). Even if the risks of catastrophe are very small, they are not zero (Feiveson, 2009), whereas with wind and solar power, the risk of catastrophe is zero. Finally, conventional nuclear power produces radioactive waste, which must be stored for thousands of years, raising technical and long-term cost questions (Barre´, 1999; von Hippel, 2008; Adamantiades and Kessides, 2009).
‘‘Breeder’’ nuclear reactors have similar problems as conventional fission reactors, except that they produce less low-level radioactive waste than do conventional reactors and re-use the spent fuel, thereby extending uranium reserves, perhaps indefinitely (Penner et al., 2008; Purushotham et al., 2000; Till et al., 1997). However, they produce nuclear material closer to weapons grade that can be reprocessed more readily into nuclear weapons (Kessides, 2010; Adamantiades and Kessides, 2009; Macfarlane and Miller, 2007; Glaser and Ramana, 2007), although some technologies have technical features that make diversion and reprocessing especially difficult—albeit not impossible (Hannum et al., 1997; Kessides, 2010; Penner et al., 2008). Kessides (2010) writes, ‘‘analyses of various reactor cycles have shown that all have some potential for diversion, i.e., there is no proliferation-proof nuclear power cycle’’ (p. 3861).
A related proposal is to use thorium as a nuclear fuel, which is less likely to lead to nuclear weapons proliferation than the use of uranium, produces less long-lived radioactive waste, and greatly extends uranium resources (Macfarlane and Miller, 2007). However, thorium reactors require the same significant time lag between planning and operation as conventional uranium reactors and most likely longer because few developers and scientists have experience with constructing or running thorium reactors. As such, this technology will result in greater emissions from the background electric grid compared with WWS technologies, which have a shorter time lag. In addition, lifecycle emissions of carbon from a thorium reactor are on the same order as those from a uranium reactor. Further, thorium still produces radioactive waste containing 231Pa, which has a half-life of 32,760 years. It also produces 233U, which can be used in fission weapons, such as in one nuclear bomb core during the Operation Teapot nuclear tests in 1955. Weaponization, though, is made more difficult by the presence of 232U.
Fusion of light atomic nuclei (e.g., protium, deuterium, or tritium) theoretically could supply power indefinitely without long-lived radioactive wastes as the products are isotopes of helium (Ongena and Van Oost, 2006; Tokimatsu et al., 2003); however, it would produce short-lived waste that needs to be removed from the reactor core to avoid interference with operations, and it is unlikely to be commercially available for at least another 50–100 years (Tokimatsu et al., 2003; Barre´, 1999; Hammond, 1996), long after we will have needed to transition to alternative energy sources. By contrast, wind and solar power are available today, will last indefinitely, and pose no serious risks. Note that our reasons for excluding nuclear are not economic. A brief discussion of the economics of nuclear power is given in Appendix A.
For these reasons, we focus on WWS technologies. We assume that WWS will supply electric power for the transportation, heating (including high-temperature heating and cooking)/cooling sectors, which traditionally have relied mainly on the direct use of oil or gas rather than electricity, as well as for traditional electricity-consuming end uses such as lighting, cooling, manufacturing, motors, electronics, and telecommunications. Although we focus mainly on energy supply, we acknowledge and indeed emphasize the importance of demand-side energy conservation measures to reduce the requirements and impacts of energy supply. Demand-side energy conservation measures include improving the energy-out/energy in efficiency of end uses (e.g., with more efficient vehicles, more efficient lighting, better insulation in homes, and the use of heat exchange and filtration systems), directing demand to low-energy use modes (e.g., using public transit or telecommuting instead of driving), large-scale planning to reduce energy demand without compromising economic activity or comfort (e.g., designing cities to facilitate greater use of non-motorized transport and to have better matching of origins and destinations, thereby reducing the need for travel), and designing buildings to use solar energy directly (e.g., with more daylighting, solar hot water heating, and improved passive solar heating in winter and cooling in summer). For a general discussion of the potential to reduce energy use in transportation and buildings, see the American Physical Society (2008). For a classification scheme that facilitates analyses of the potential gains from energy efficiency, see Cullen and Allwood (2009).
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