Providing all Global Energy with Wind, Water, and Solar Power,

Abstract
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) 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 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 converted to electricity and electrolytic hydrogen for all
purposes. The additional land footprint and spacing needed are ~0.41% and ~0.59% of world
land area, respectively. We suggest producing all new energy with WWS by 2030 and replacing
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.
http://www.stanford.edu/group/efmh/jacobson/Articles/I/WWSEnergyPolicyPtI.pdf

4. Quantities and Areas of Plants and Devices Required

How many WWS power plants or devices are required to power the world and U.S.? Table 4 provides an estimate for 2030, assuming a given fractionation of the demand (from Table 2) among technologies. Wind and solar together are assumed to comprise 90% of the future supply based on their relative abundances (Table 3). Although 4% of the proposed future supply is hydro, most of this amount (70%) is already in place. Solar PV is divided into 30% rooftop, based on an analysis of likely available rooftop area (Jacobson, 2009), and 70% power plant. Rooftop PV has three major advantages over power-plant PV: rooftop PV do not require an electricity transmission and distribution network, they can be integrated into a hybrid solar system that produces heat, light, and electricity for use on site (Chow, 2010), and they do not require new land area. Table 4 suggests that almost 4 million 5-MW wind turbines (over land or water) and about 90,000 300-MW PV plus CSP power plants are needed to help power the world. Already, about 0.8% of the wind is installed.

The total footprint on the ground (for the turbine tubular tower and base) for the 4 million wind turbines required to power 50% of the world’s energy is only ~48 km2, smaller than Manhattan (59.5 km2) whereas the spacing needed between turbines to minimize the effects of one turbine reducing energy to other turbines is ~1.17% of the global land area. The spacing can be used for agriculture, rangeland, open space, or can be open water. Whereas, wind turbines have foundations under the ground larger than their base on the ground, such underground foundation areas are not footprint, which is defined as the area of a device or plant touching the top surface of the soil, since such foundations are covered with dirt, allowing vegetation to grow and wildlife to flourish on top of them. The footprint area for wind also does not include temporary or unpaved dirt access roads, as most large-scale wind will go over areas such as the Great Plains and some desert regions, where photographs of several farms indicate unpaved access roads blend into the natural environment and are often overgrown by vegetation. Offshore wind does not require roads at all. In farmland locations, most access roads have dual purposes, serving agricultural fields as well as turbines. In cases where paved access roads are needed, 1 km2 of land provides ~200 km (124 miles) of linear roadway 5 m wide, so access roads would not increase the footprint requirements of wind farms more than a small amount. The footprint area also does not include transmission, since the actual footprint area of a transmission tower is smaller than the footprint area of a wind turbine. This is because a transmission tower consists of four narrow metal support rods separated by distance, penetrating the soil to an underground foundation. Many photographs of transmission towers indicate more vegetation growing under the towers than around the towers since areas around that towers are often agricultural or otherwise used land whereas the area under the tower is vegetated soil. Since the land under transmission towers supports vegetation and wildlife, it is not considered footprint beyond the small area of the support rods.

For non-rooftop solar PV plus CSP, the areas required are considered here to be entirely footprint although technically a walking space, included here as footprint, is required between solar panels (Jacobson, 2009). Powering 34% of the world with non-rooftop solar PV plus CSP requires about one-quarter of the land area for footprint plus spacing as does powering 50% of the world with wind but a much larger footprint area alone than does wind (Table 4). The footprint area required for rooftop solar PV has already been developed, as rooftops already exist. As such, these areas do not require further increases in land requirements. Geothermal power requires a smaller footprint than does solar but a larger footprint than does wind per unit energy generated. The footprint area required for hydroelectric is large due to the large area required to store water in a reservoir, but 70% of needed hydroelectric power for a WWS system is already in place.

Together, the entire WWS solution would require the equivalent of ~0.74% of the global land surface area for footprint and 1.18% for spacing (or 1.9% for footprint plus spacing). Up to 61% of the footprint plus spacing area could be over the ocean if all wind were placed over the ocean although a more likely scenario is that 30-60% of wind may ultimately be placed over the ocean given the strong wind speeds there (Figure 1). If 50% of wind energy were over the ocean, and since wave and tidal are over the ocean, and if we consider that 70% of hydroelectric power is already in place and that rooftop solar does not require new land, the additional footprint and spacing areas required for all WWS power for all purposes worldwide are only ~0.41% and ~0.59%, respectively, of all land worldwide (or 1.0% of all land for footprint plus spacing).


Providing all Global Energy with Wind, Water, and Solar Power, Part I: Technologies, Energy Resources, Quantities and Areas of Infrastructure, and Materials, pg 11, 12

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).

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.

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)...

...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 electricity sector during this period; Jacobson, 2009)...

...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., 2010; 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 (Barré, 1999; von Hippel, 2008; Adamantiades and Kessides, 2009).

Since wind turbines replace other electricity sources that also produce heat in this manner (Sta. Maria and Jacobson, 2009), wind turbines (and other renewable electricity sources) replacing current infrastructure cause no net heat addition to the atmosphere.