Friday, October 31, 2008

Is nuclear power green?

Rachel's Democracy & Health News #983, October 30, 2008

[Rachel's introduction: How can people judge whether a technology is green or not? They can compare it to the 12 principles of green engineering and the 12 principles of green chemistry. Here we compare nuclear power to these green principles.]

By Peter Montague

We are told that nuclear power is about to achieve a "green renaissance," "clean coal" is just around the corner, and municipal garbage is a "renewable resource," which, when burned, will yield "sustainable energy." On the other hand, sometimes we are told that solar, geothermal and tidal power are what we really need to "green" our energy system.

How is a person to make sense of all these competing claims?

Luckily, scientists have developed two sets of criteria that we can use to judge the "greenness" of competing technologies. The first is called "The 12 principles of green engineering" and the second is "The 12 principles of green chemistry."

Both sets of principles were developed by teams of technical experts and published in peer-reviewed journals. They are now widely understood and endorsed. Most importantly, they offer ordinary people, as well as experts, a way to decide which technologies are worth supporting and which ones should be phased out or never developed at all. Even most members of Congress should be able to understand and apply these principles.

You can find both sets of principles listed at the end of this article.

In this short series, we'll apply these principles as a "filter" to nuclear power, coal power, so-called "waste to energy" incinerators, and finally to solar power.

These comparisons will not be exhaustive because the green principles are just that -- principles -- and they clarify without requiring great detail.

Nuclear Power and Green Engineering

So let's get right to it. Anyone can readily see that nuclear power violates green engineering principles #1 (prefer the inherently nonhazardous) and #2 (prevent instead of manage waste). Nuclear power produces radioactive wastes and "spent fuel," which are are exceptionally hazardous and long-lived. Just mining the fuel -- uranium -- has littered the western U.S. (and other parts of the world) with mountainous piles of radioactive sand ("uranium tailings"), which no one knows how to stabilize or detoxify, and which continually blow around and enter water supplies and food chains.

Furthermore, nuclear power violates green engineering principle #12 (raw materials should be renewable and not depleting) because it depends on uranium for fuel and the world supply of uranium is finite and dwindling.

Nuclear power also violates green engineering principles #9 (design for easy disassembly) and #11 (design for commercial re-use) because, after a nuclear power plant has lived out its useful life, many of its component parts remain extremely radioactive for centuries or aeons. Large parts of an old nuclear plant have to be carefully disassembled (by people behind radiation shields operating robotic arms and hands), then shipped to a suitable location, and "mothballed" in some way -- usually by burial in the ground. An alternative approach is to weld the plant shut to contain its radioactivity, and walk away, hoping nothing bad happens during the next 100,000 years or so. In any case it's clear that nuclear power violates principles #9 and #11 of green engineering.

Nuclear Power and Green Chemistry

When we compare nuclear power against the principles of green chemistry, we can readily see that it violates #1 (prevent waste), #3 (avoid using or creating toxic substances), and #10 (avoid creating persistent substances) because of the great toxicity and longevity of radioactive wastes. It also violates #7 (use renewable, not depleting, raw materials) because the basic fuel, uranium, is not renewable. Plans for extending the life of global uranium supplies all entail the use of "breeder reactors," which create plutonium. But plutonium itself violates green chemistry principles 1, 3, 4 and 10. The scientist who discovered plutonium (Glenn Seaborg) once described it as "fiendishly toxic." Plutonium is also the preferred material for making a rogue atomic bomb, which is why the New York Times has called the world's existing supplies of plutonium "one of the most intractable problems of the post-cold-war era."[1]

Lastly, nuclear power plants produce what is called "spent fuel" -- a misnomer if there ever was one. "Spent" makes it sound tired and benign. There is nothing benign about "spent fuel." It is tremendously radioactive -- so much so that it must be stored in a large pool of water to keep it cool. If someone accidently (or malevolently) drained the "spent fuel pool" that exists on-site at nearly every nuclear reactor, the "spent fuel" would spontaneously burst into flame and burn out of control for days, releasing clouds of highly-radioactive cesium-137 all the while. Green chemistry principle #12 says our technologies should be chosen to minimize the potential for accidents such as releases and fires. By this standard, nuclear power does not measure up.

On the face of it, applying a "green principles" test to nuclear power would force us to conclude that it fails by any objective standard and that we should be looking elsewhere for green energy.

Next installment: coal


The 12 Principles of Green Engineering

[First published in Paul T. Anastas and J.B. Zimmerman, "Design through the Twelve Principles of Green Engineering", Environmental Science & Technology Vol. 37, No. 5 (March 1, 2003), pgs. 95A-101A.]

Principle 1: Designers need to strive to ensure that all material and energy inputs and outputs are as inherently nonhazardous as possible.

Principle 2: It is better to prevent waste than to treat or clean up waste after it is formed.

Principle 3: Separation and purification operations should be designed to minimize energy consumption and materials use.

Principle 4: Products, processes, and systems should be designed to maximize mass, energy, space, and time efficiency.

Principle 5: Products, processes, and systems should be "output pulled" rather than "input pushed" through the use of energy and materials.

Principle 6: Embedded entropy and complexity must be viewed as an investment when making design choices on recycle, reuse, or beneficial disposition.

Principle 7: Targeted durability, not immortality, should be a design goal.

Principle 8: Design for unnecessary capacity or capability (e.g., "one size fits all") solutions should be considered a design flaw.

Principle 9: Material diversity in multicomponent products should be minimized to promote disassembly and value retention.

Principle 10: Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows.

Principle 11: Products, processes, and systems should be designed for performance in a commercial "afterlife".

Principle 12: Material and energy inputs should be renewable rather than depleting.


The 12 Principles of Green Chemistry

[First published in Martyn Poliakoff, J. Michael Fitzpatrick, Trevor R. Farren, and Paul T. Anastas, "Green Chemistry: Science and Politics of Change," Science Vol. 297 (August 2, 2002), pgs. 807-810.]

1. It is better to prevent waste than to treat or clean up waste after it is formed.

2. Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.

3. Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

4. Chemical products should be designed to preserve efficacy of function while reducing toxicity.

5. The use of auxiliary substances (e.g., solvents, separation agents, and so forth) should be made unnecessary wherever possible and innocuous when used.

6. Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure.

7. A raw material or feedstock should be renewable rather than depleting wherever technically and economically practicable.

8. Unnecessary derivatization (blocking group, protection/deprotection, temporary modification of physical/chemical processes) should be avoided whenever possible.

9. Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.

10. Chemical products should be designed so that at the end of their function they do not persist in the environment and break down into innocuous degradation products.

11. Analytical methodologies need to be developed further to allow for real-time in-process monitoring and control before the formation of hazardous substances.

12. Substances and the form of a substance used in a chemical process should be chosen so as to minimize the potential for chemical accidents, including releases, explosions, and fires.


[1] Matthew L. Wald, "Agency To Pursue 2 Plans to Shrink Plutonium Supply," New York Times December 10, 1996, pg. 1.