David Schowalter, PhD

Getting Real About Solutions for Global Warming

June 2006

I consider myself an environmentalist, so the last six years have been very difficult in that regard.  Some government policies have been actively destructive, such as the attempted relaxation of New Source Review rules, which dictate how large of an upgrade must occur before power plants are required to install modern air pollution equipment for meeting clean air standards.  Others have merely shown a severe lack of environmental leadership, such as failure to sufficiently tighten automotive fuel economy standards, or to admit and confront the global warming challenge or fully support renewable energy development.  Yet, in spite of all of these failures, I see a silver lining in the current policies—the strong support for advancement and development of nuclear and “clean coal” power.

Many environmentalists strongly disagree with this position, but there are some notable exceptions to the nuclear power position, at least.  Renowned British environmentalist and scientist James Lovelock, one of the developers of the “GAIA theory” has urged a resurgence of nuclear power in order to prevent and hopefully reverse global warming¹.  Patrick Moore, co-founder of Greenpeace, has also been lobbying for more nuclear power². 

In general, the environmental movement tends to favor renewables and increases in efficiency as a way to curb emissions, including carbon dioxide, the primary cause of global warming.  When feasible, I concur wholeheartedly.  In addition to being an environmentalist, however, I am also a pragmatist and technologist who knows that a growing economy and population mean that efficiency gains will only take us so far.  Many forms of renewables are promising, but will not solve our energy needs any time soon.  Let’s look briefly at each of the major forms of renewable energy, along with their promises and limitations.

Biomass

Biomass energy refers to fuel that comes from plant life.  The plant-derived fuel is combusted in either solid or liquid form.  While air pollution such as NOx and Carbon Monoxide may still form, biomass is carbon-neutral, meaning that whatever carbon dioxide results from combustion would presumably be reabsorbed through photosynthesis by plants grown for additional fuel.  The main problem with biomass is efficiency.  The heating value of solid fuel is typically smaller than coal, but can often be used economically, particularly when co-firing with coal.  Biomass-derived liquid fuels can be much more problematic from an efficiency standpoint.  Refining takes a significant amount of energy.  Today’s method of creating ethanol, for example, requires more energy than can be extracted from it³.  While more efficient production methods have been proposed⁴, the energy balance remains a question, as well as the land requirements.  Providing enough switchgrass to power the planet, for example, would require that all arable land in the world be used for that purpose⁵. 

Wind Energy

The use of large scale wind energy has been experiencing healthy growth over the last ten years, and it should definitely be exploited further.  In many cases, wind energy projects have been the battleground for an environmental movement at war with itself, as some favor the progress in renewable energy while others worry about the impact on natural views and wildlife.  The main practical problem with wind energy is its intermittency (the power generated scales as the wind velocity cubed), rendering it completely inappropriate for dealing with base electrical loads.  The total U.S. wind potential is estimated at 1.5 trillion kilowatt-hours per year⁶, which should be compared with the 29 trillion kilowatt-hours per year of energy currently consumed in all forms in 2005, or the 6.8 trillion from coal alone⁷. 

Solar Power

The promise of solar power gained a lot of press in the 1970’s, then lost favor during the 1980’s as memories of the energy crisis began to fade and solar cell prices remained high.  While it hasn’t received much attention in recent years, the number of installed solar power systems in the United States has been climbing steadily. 

At a conservative 10% efficiency, 10% of the energy needs of the U.S. could be met by an area equivalent to the rooftops of every single family residence5.  Two major problems with solar power are the need for silicon, and intermittency of the power.  Particularly because of the computer industry, silicon is an element in high demand, and this is partially responsible for the high cost of solar cells.  Luckily, thin-film solar cells that can be built without the use of silicon are being developed, though are not yet ready for the market.  The intermittency will forever be a limitation of solar power, rendering it inappropriate for base load capacity, much like wind power.  Still, solar energy technology development holds promise and is grossly under-funded.

Clean Coal and Nuclear Power—The Promise of Carbon-Neutral Base Load Capacity

If we include the current use of hydropower (about 3%), which is unlikely to grow in the U.S. because of other environmental considerations, the above data show that in the best of all possible worlds, perhaps 35 % of the power in the U.S. could come from renewable energy.  Global warming from carbon dioxide emissions is already exceeding dangerous levels.  More disconcertingly, continued delay in finding a solution could lead to irreversible consequences.  One recent study⁸ suggests that to avoid this fate, we must be replacing current technology coal fired power plants with carbon-neutral power generation equivalent to ¾ of the capacity of China’s Three Gorges Dam every year for the next 260 years.  This is a tremendous task.  What steps realistically can be taken right now to begin?

Clean Coal Technology

The United States is sometimes called the “Saudi Arabia of coal.”  It has more coal reserves than any other country in the world.  The United States and Russia together have more coal reserves than the next six producers combined⁹.  It is only practical to investigate how to use coal power while eliminating carbon dioxide and other air pollution emissions.  The FutureGen program, first announced by President Bush in 2003, is a $1 billion cost-shared project aimed at creating the world’s first zero emissions combined electricity and hydrogen production plant using coal as a fuel source.  The plant is envisioned to operate at 275 MW, sequestering one million metric tons of carbon dioxide per year, most likely in a combination of unmineable coal beds, depleted oil and gas reservoirs, deep saline aquifers, and for use in aging oil fields for enhanced recovery.  The plant will operate a gasifier running on coal, water, and oxygen separated from air.  The exhaust stream will first go through a gas cleaning process which separates sulfur and carbon dioxide, leaving a hydrogen rich stream to be used in a gas turbine, possibly coupled to a Solid Oxide Fuel Cell (SOFC), using a steam turbine in combined cycle, all generating electricity.  Additional hydrogen can be generated for transportation.  It is anticipated that the plant will achieve 99% sulfur removal, more than 90% mercury removal, emitting less than 0.05 lb/million BTU NOx emissions and less than 0.005 lb/million BTU in particulates.   Promising near term technologies such as circulating fluidized bed combustors, Integrated Gasification Combined Cycle plants (IGCC), and multi-pollutant control systems are being co-funded through the Clean Coal Power Initiative, a sister program to FutureGen. 

To be sure, there are challenges for “clean coal,” not the least of which is the carbon dioxide sequestration.  There are valid safety questions about geological storage, but promising technologies are developing, such as sub-sea injection in regions below the ocean floor where the pressures are high enough for the carbon dioxide to be a liquid more dense than seawater, and the creation of mineral carbonates which can safely be returned as stable solid waste into the coal mines. 

Nuclear Energy

After the Three-Mile Island and Chernobyl accidents, nuclear power became very unpopular, particularly in the United States. It is worth noting, however, that there has never been a death in the U.S. associated with nuclear power.  The Chernobyl plant never would have been approved in the U.S. because there was no containment vessel, and the fuel was designed to increase the reaction rate as power increased.   Fifty people were killed directly from that accident, and there have been an additional 4,000 cases of thyroid cancer, which is 99% treatable (meaning another 40 deaths can be assumed).  While this does not address the permanent damage to that region or possible birth defects, these numbers do provide an interesting perspective, especially given the health impacts from coal mining and air pollution on a regular basis.

The great environmental benefit to nuclear power is the complete lack of associated air pollution.  While there are some greenhouse gas emissions associated with plant construction and fuel transport, it is negligible compared to fossil fuel power generation.  This is the primary reason that some prominent environmentalists are coming out in favor of increased usage of nuclear energy.

Nuclear energy, particularly in the U.S. and other western countries, has been extremely safe and is getting even safer.  New “Generation III” plant designs now being approved have incorporated many passive safety features, including gravity feeds and heat exchangers driven by natural circulation, eliminating the need for many emergency pumping systems which rely on backup power.  This trend will continue with “Generation IV” designs, which will have even more passive safety features.  The Energy Policy Act of 2005 streamlined the permitting process by creating standards for licensing and by combining the permitting for construction and operating licenses, encouraging the development of new nuclear power plants in the U.S.  Additionally, it provided funding for research and development of Generation IV nuclear reactors.

Even those who acknowledge nuclear power’s safety record generally have a concern about waste.  This is a valid concern, given that the current waste stream from light water reactors is dangerously radioactive for many thousands of years.  Still, the amount of waste is relatively small, given the large amount of power that has been generated.  The total volume of waste currently in existence from 40 years of nuclear power would fit on a football field, and be about five yards deep. 

The waste problem could be reduced even further with reprocessing technology.  Reprocessing of nuclear waste would recover the highly radioactive portion of the spent fuel for reuse, while the remainder would have a much lower volume and a much lower half-life (hundreds of years rather than thousands).  The problem with reprocessing  in the past (the so-called PUREX process) has been that weapons grade plutonium was a by-product of the procedure, and the U.S. decided to stop reprocessing in the 1970’s in order to discourage other countries from doing so.  As it turned out, most European countries continued to reprocess anyway.  While still controversial, more recent development has led to the UREX+ process, which bypasses the generation of high purity plutonium.  President Bush and the Department of Energy have proposed a Global Nuclear Energy Partnership (GNEP) aimed at further development of the UREX+ process, with key nuclear powers doing the reprocessing while supplying fuel and reprocessing services to other nations.  The goal is to make nuclear power truly sustainable.

Environmental Legacy

Given the seriousness, urgency, and scale of the global warming problem, future generations may look upon this era with some gratitude. While the government has not provided appropriate support for renewable energy, nor taken the necessary steps to legislate a reduction in greenhouse gases, it has promoted the most important technologies needed to make that reduction.  Now we need the active involvement of national leaders
who are true  advocates for the environment and can make  the public aware of the seriousness of the problem,  embrace nuclear and clean coal energy technology, and obtain a mandate to legislate a carbon trading program that will give us the necessary reductions to avoid disaster.

• ¹ Lovelock, James, 2005.  “Our Nuclear Lifeline.”  Readers Digest, March 2005. 
• ²Moore, Patrick, 2006.  “Going Nuclear—A Green Makes the Case.”  Washington Post, Sunday, April 16, P. B1.
• ³Pimental, D. and Patzek, T.  2005.  “Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower.”  Natural Resources Research, Vol. 14, No. 1. 
• ⁴Greene, N. et al. 2004. “How Biofuels Can Help End America’s Oil Dependence”, Natural Resources Defense Council Report, December, 2004.
• ⁵Lewis, N.S. (chair), 2005.  “Basic Research Needs for Solar Energy Utilization”.  Report on the Basic Energy Sciences Workshop on Solar Energy Utilization, April 18-21, 2005. California Institute of Technology, http://www.sc.doe.gov/bes/reports/files/SEU_rpt.pdf,
• ⁶ Elliott, D.L., and M.N. Schwartz  1993. „Wind energy potential in the United States,” Pacific Northwest Laboratory PNL-SA-23109, Richland, WA
• ⁷Energy Information Administration, http://www.eia.doe.gov/oiaf/aeo/excel/figure3_data.xls
• ⁸ Lam, H.  2006.  http://www.princeton.edu/~lam/documents/SciencePolicy.ppt
• ⁹ DOE/EIA-0484, International Energy Outlook 2005

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