Rachel's Democracy & Health News #990, December 18, 2008


[Rachel's introduction: A detailed new study from the Atmosphere/ Energy Program at Stanford University examines 10 electric power sources and two liquid fuel options, comparing them by 11 different criteria. The study concludes that ethanol, nuclear, and coal-with- carbon-storage (CCS) are dirty, inefficient, and wasteful compared to wind, direct sunlight, geothermal and ocean energy. These cleaner, inexhaustible sources could eliminate global warming gases, give us energy security and meet the nation's (and the world's) energy needs forever, the study concludes.]

By Peter Montague

A detailed new report from Stanford University reviews and ranks major energy-related solutions to global warming, air pollution deaths, and energy security. The report is available now online with extensive supplementary materials, and will soon appear in the journal Energy & Environmental Solutions. The author is Mark Z. Jacobson, director of the Atmosphere/Energy Program at Stanford in Palo Alto, Calif.

[Read Stanford's press release announcing the study or this news story from R&D Magazine, or watch a video of Mark Jacobson discussing his new study.]

The report assumes that all U.S. gasoline-powered vehicles will shift entirely to electric power or ethanol fuel, and it then compares 10 ways of generating the necessary electricity and two ways of making ethanol fuel (basically, from corn or cellulose). Each of these 12 options is then evaluated against 11 different criteria and a final ranking is calculated.

The power-source technologies considered are:

(1) Solar photovoltaics -- the dark blue glassy panels that convert sunlight directly into electricity;

(2) Concentrated solar power -- arrays of mirrors (or lenses) that focus sunlight to heat a fluid to high temperature in a collector (such as a pipe), generating steam to turn a turbine to make electricity;

(3) Wind turbines, each up to 5 megawatts in size, with blades 160 meters (525 feet) long, which turn a turbine to make electricity. storing the electricity in batteries;

(4) Wind turbines making electricity (see paragraph above) but storing the energy as hydrogen;

(5) Geothermal -- extracting some of the heat that lies deep below the surface everywhere on earth;

(6) Hydro dams -- like Hoover dam -- a well-known technology that currently provides 17.5% of the world's electricity, more than any other single technology;

(7) Ocean wave energy -- machines that move with the waves (for example, a bobbing buoy) to generate electricity;

(8) Tidal energy -- machines that extract energy from flowing tidal waters and convert it to electricity;

(9) Nuclear power plants that split (fission) atoms of enriched uranium, or plutonium, to generate heat to boil water to turn a turbine to make electricity;

(10) Coal-fired power plants that burn pulverized coal, which could be fitted with end-of-pipe filters to capture carbon dioxide gas, compress it into a liquid, pipe it to a "suitable location" and bury it a mile or so underground, hoping it will stay there forever.

(11) Ethanol (alcohol) made from corn (or from sugarcane, wheat, sugar beets or molasses);

(12) Ethanol made from cellulose (switch grass; wood waste; wheat or corn stalks; other stalks; or miscanthus grasses).

The report evaluates each of these 12 sources of energy by 11 different criteria, as follows:

(1) Abundance of the resource; each of these resources is available in vast quantities but some are far more abundant than others. Solar photovoltaics lead the pack by far -- converting just 1% of available sunlight to electricity could supply more than the world's total power needs (not just the world's electricity needs). Wind power is abundant, too: available wind power is five time as large as the world's total energy needs and 20 times as large as the world's electricity needs.

(2) Climate-relevant emissions (carbon dioxide, plus other greenhouse gases, such as methane, converted to their carbon-dioxide equivalent based on their global-warming potential). This is expressed as grams of CO2-equivalent emitted per kiloWatt-hour of electricity (or electricity equivalent, in the case of ethanol) for each of the 12 technologies. This calculation takes into consideration direct and indirect emissions throughout the life cycle of a machine (whether a wind turbine or a nuclear power plant).

The study factors in "opportunity cost emissions" -- emissions that will occur from existing dirty sources of power during the delay period while new machines are being brought online. For example, a wind farm can be brought online in 2-5 years but a nuclear power plant requires 10 to 19 years and a coal-with-CCS plant requires 6 to 11 years. Thus a wind farm can displace existing CO2 and air pollution emissions much faster than either nuclear or coal-with-CCS, raising the "opportunity costs" of nuclear and coal plants because of inherent delays in construction.

The results in this section are startling. For example, coal-with- carbon-capture emits 60 times as much CO2 as wind energy for each kiloWatt-hour of electricity generated,

(3) Human deaths from air pollution are calculated for each of the 12 technologies; here corn and cellulosic ethanol fare worst, with coal- with-CCS and nuclear second-worst. Wind-power is best by far. This report breaks new ground, tackling some of the difficult questions surrounding proliferation of nuclear power plants, which unavoidably increase the odds that some time in the next 30 years a rogue nuclear weapon will be detonated with great loss of life.

(4) The "footprint" of each technology -- the area of land and/or ocean required. Here the ethanols fare far worse than all the others.

(5) Spacing -- This is the area required by the "footprint" (see preceding paragraph) plus the spacing needed between installations of wind, tidal, wave and nuclear plants (which require security buffers).

(6) Water use; again the ethanols are far worse than any of the alternatives;

(7) Effects on wildlife and the natural environment are considered separately for each of the 12 technologies. Here we can only hit the highlights of this long section of the report. For example, this section explicitly addresses the concern that wind turbines kill large numbers of bats and birds each year. The report concludes that, in the worst case, if 1.4 to 2.3 million 5-megawatt wind turbines were installed worldwide to eliminate all human-created CO2 emissions, total global bird kill would be 1.4 to 14 million birds per year. This large number represents less than 1% of birds killed each year by humans including by communication towers and their guy wires (which birds smash into at night, attracted by lights), window panes, and pet cats or former-pet feral cats. Although killing 1.4 to 14 million birds per year is not trivial, it can be weighed against eliminating enough air pollution to save an estimated 2.4 million human lives each year and a large (though not well-quantified) reduction in harm to wildlife by eliminating toxic air and water pollution. Wild animals, including birds, are harmed by pollution just as humans are.

(8) Thermal pollution -- heat released from machines locally -- particularly nuclear and coal plants -- often as hot water from cooling towers;

(9) Releases of toxic chemicals and radioactive materials; again, wildlife and humans would both benefit very substantially if we replaced existing fossil-fueled technologies and nuclear technologies with cleaner alternatives.

(10) Energy supply disruption. It is important to evaluate the potential of each technology to be disrupted by terrorism, war, or natural disaster. Here the dispersed technologies (wind, solar photovoltaics, wave and tidal) fare best and the most centralized (nuclear, coal-with-CCS, and concentrated solar) fare worst.

(11) Intermittency. This is an important consideration because we need power 24/7 but the sun does not shine at night and the wind sometimes dies down at any given locale.

The issue of intermittency is crucial to the success of power systems dependent on wind and sun, and the report treats it as an engineering problem that can be solved. The report says, "Whether or not intermittency affects the power supply depends on whether effort[s] to reduce intermittency are made." The report then describes 5 ways to reduce intermittency:

(a) Interconnecting geographically-dispersed naturally-intermittent energy sources (e.g., wind, solar, wave, tidal). The author of this report, Mark Z. Jacobson, published an earlier detailed study of the reliability benefits that could be gained by modernizing the transmission grid to interconnect dispersed energy sources;

(b) Use a reliable energy source, such as hydro dams, or geothermal power plants, to smooth out supply or to match demand;

(c) Use smart meters to provide maximum electric power to charging vehicle batteries when power generation is high, reducing the power to charging vehicle batteries at other times, thus smoothing out demand to match supply;

(d) Store electric power for later use; electricity can be stored as hydrogen, or in the batteries of all the electric vehicles plugged into the grid at any moment; or as pumped hydroelectric storage (water pumped uphill at night runs back down during the day, generating power); or as compressed air in underground vaults or turbine nacelles; or in flywheels; or in molten salts (as is being done with some concentrated solar plants today). The disadvantage of stored power is conversion losses in both directions rather than just one.

(e) Forecast short-term weather to plan better for energy needs; in many locales, with a good database of measurements, weather can be forecast one to four days in advance with good accuracy, helping grid managers anticipate both demand and supply.

The 12 energy sources are rated on the 11 criteria and then a weighting factor is applied. The weighting factor indicates the importance of the criterion -- global warming and air pollution deaths are given a weight of 22, while thermal pollution has a weight of 1. The weighting factors themselves sum to 100. Then a total rank is calculated (1 is best, 12 is worst) assuming that all vehicles in the U.S. are converted to electricity and powered by the particular technology being ranked.

The Results: Hand Me the Envelope, Please

Wind-powered battery-electric vehicles are ranked #1, best by far with a weighted average of only 2.09. Second is wind-powered hydrogen- storage vehicles (weighted average, 3.22); third is concentrated solar-powered battery-electric vehicles (weighted average, 4.28); fourth place goes to geothermal-powered battery-electric vehicles (weighted average, 4.60); fifth is tidal-powered battery-electric vehicles (weighted average, 4.97); sixth is photo-voltaic-powered battery-electric vehicles (weighted average, 5.26); seventh is wave- powered battery- electric vehicles (weighted average, 6.11); eighth place goes to hydro- dam-powered battery-electric vehicles (weighted average, 8.40); ninth place goes to two technologies that are tied with equal scores -- nuclear powered battery-electric vehicles (weighted average, 8.50) and coal-with-CCS-powered battery-electric vehicles (weighted average, 8.47); 11th place goes to vehicles powered by corn-based E-85 fuels (weighted average, 10.6) and 12th place goes to vehicles burning cellulose-derived E85 fuel (weighted average, 10.7).

According to the report, both methods of producing ethanol make the global warming problem worse, not better. Given that the U.S. Congress has bet the farm on ethanol (so to speak), this finding does not inspire confidence that Congress will make rational choices based on the kind of data found in this report. Where is the Congressional Office of Technology Assessment when you need it? (Gone the way of the Dodo bird in 1995, during the reign of Newt Gingrich.)

To get all this into perspective, the report points out that we could power all our light-duty and heavy-duty gasoline-powered vehicles with wind -- by converting them to electricity and supplying their power by deploying 73,000 to 144,000 5-megawatt wind turbines. Is this doable? Of course it is. During the four years of World War II, the U.S. built more than 300,000 airplanes. Deploying half that number of wind turbines is definitely doable. Is it affordable? The Stanford report does not address questions of dollar cost. But we can do a crude calculation: given that the U.S. economy generates roughly $14 trillion each year, even if we were to spend $2 trillion on renewable energy during the next 15 years, it would represent less that 1% of gross domestic product (GDP) during the period.

Deploying 144,000 wind turbines would reduce our global warming emissions by 33% and would eliminate about 15,000 deaths from air pollution each year in the U.S.

Carrying the argument further, the report points out that the U.S. could eliminate 100% of its global-warming emissions by powering the economy with 389,000 to 645,000 5-megawatt wind turbines. Going even further, the report points out that worldwide emissions of fossil- fuel carbon could be eliminated entirely by powering the world economy with 2.2 to 3.6 million 5-megawatt wind turbines. No one expects the world to rely exclusively on wind-power, but the calculation reveals just how large and clean the wind resource really is.

Some limitations of the study

By design, this study does not take into account energy savings that are readily available through improved efficiencies -- it only discusses efficiencies inherent in shifting from gasoline-powered internal combustion vehicles (with a tank to wheel efficiency of 17%) to battery-electric vehicles with a plug-to-wheels efficiency of 86%). It omits discussion of the many efficiencies that are readily available at reasonable cost in the built environment, including better insulation, less energy-intensive materials, combined heat-and- power installations, and so on.

The study will be criticized (unfairly, it seems to me) for assuming that we will meet the ever-expanding power demands of ever-growing economies, rather than looking for ways to shrink demand. The purpose of the study was to evaluate energy-supply alternatives, which it has done remarkably well.

The study does not take into account the large number of human deaths caused each year by burning coal and oil -- including not only fine and ultrafine particles released from smoke stacks, exhaust pipes, and chimneys (from coal plants, diesel vehicles and oil-fired home furnaces) but also the 120 million tons of coal combustion waste produced each year in the U.S., most of which gets buried in the ground somewhere, often contaminating ground water with various toxic metals and organic compounds (polycyclic aromatic hydrocarbons, dioxins, furans, and so on).

Despite these limitations, this is an exceedingly important study that breaks new analytic ground and provides clear guidance for policy makers. Unlike some previous energy studies from Stanford and Princeton, which promoted coal-with-carbon storage and were funded by the oil, coal and automobile industries, the present study was not supported by any interest group, company, or government agency.

We can only hope that members of Congress -- and Mr. Obama's choice for Secretary of Energy, Steven Chu -- are sufficiently on the ball to read this new report carefully, consider the options it evaluates, and then act upon it in time to avert catastrophe.