Sunday, August 30, 2009

Energy and Land Use:

Energy and Land Use

[Wikipedia Photo]

In discussions of new forms of energy supply, issues of land use are often ignored. Consequently, I was happy to see an article about a report by the Nature Conservancy that spells out the land use requirements of some of the options. The full report provides a more complete analysis. The report was written with the objective of analyzing energy legislation under consideration, but the quantitative information has broader uses.

Both the article and the report make it clear that options such as increased use of biomass and wind have significant implications for land use. In an era of NIMBY (Not in My Backyard), BANANA (Build Absolutely Nothing Anywhere Near Anyone), and NOPE (Not on Planet Earth), the land use ramifications should be prominently considered.

The full report has helped clarify some issues that have always puzzled me. For example, claims of significant land use by windmills have sometimes seemed specious, as windmills can often be cited on farmland, which would appear to allow for dual use of the same land. Thus, from that perspective, land use would not seem to be a significant issue for windmills. However, the report notes that the full land impact takes into account more than the human uses of the land. The report estimates that the direct footprint of windmills is 3-5% of the total affected area. Fragmenting habitats and species avoidance behavior account for 95-97% of the total footprint. What is not clear is how this figure was derived and whether it applies to land that is already used for agricultural purposes. Even if the ratio is lower in some cases (as I believe would be appropriate for land already in use), it makes the point that the impact of a windmill exceeds its physical footprint.

In addition, I might add that many people apparently consider windmills unsightly, and increasingly, laws are being passed to restrict their siting. So far, these laws mainly have to do with concerns about destroying scenic, natural environments, and thus, prohibit siting on mountain ridges. The most recent example is legislation in North Carolina. However, some reports are beginning to emerge that attribute a variety of health effects to wind turbines. While I see no evidence that these claims are credible, they may result in increasing restrictions on siting. There are other options, such as offshore siting, but these increase costs and potential impacts on migratory birds.

The report also covers land use issues for other energy sources. In particular, an increased use of biomass for energy generation has potentially the largest impact on land use. It covers this scenario in some detail, and in particular, notes some of the interactions with food production requirements. Using land presently used for food production would not create new land use impacts. However, it is likely that other land would have to be devoted to food production, so the land use would increase in one way or another. The alternative--increased food costs and/or food shortages-have different, but equally undesirable, impacts.

The report gives less space to the energy sources that have the lowest land use impacts, but readers of this blog will be happy to know that nuclear power was the least energy-intensive energy source. Only energy efficiency measures had a lower land use impact.

As always, I would emphasize that no one measure can give us a true sense of the pros or cons of an energy technology. Nuclear power proponents should not react gleefully to the fact that wind is more land intensive or that it has its own detractors. But by the same reasoning, proponents of wind or solar power should not cast their technologies as the sole solution to our energy needs. Land use issues are only one of a number of issues that will have to be balanced to find an appropriate mix of technologies for the future.

Monday, August 24, 2009

Nuclear Power
Greenhouse Gases

Paducah Enrichment Plant

For my first example of “The Rest of the Story,” I’d like to explore the question of net energy generation from nuclear power.

One of the stranger allegations I keep hearing is that nuclear power generation really results in a very high level of carbon emissions. The allegations acknowledge that the reactors themselves don’t produce carbon emissions, but point to the rest of the nuclear fuel cycle.

The allegations seem to be based on the fact that the enrichment step of the nuclear fuel cycle has historically been an energy intensive step, and that the energy used for enrichment has traditionally been supplied by coal-fired power plants, which emit carbon dioxide into the atmosphere.

Some sources even suggest that the energy required in the nuclear fuel cycle is so large that the reactors do not really supply much net energy, or allow much net reduction in greenhouse gas emissions.

This allegation doesn’t hold up to analysis, and numerous comparisons of greenhouse gas emissions from various energy sources routinely put nuclear in the same range as wind and solar energy—very low.

Even for the “old” technology for uranium enrichment, gaseous diffusion (still used in the United States), the energy required for uranium enrichment, while substantial, is still only a small fraction of the total energy generated by the nuclear power plant. Using figures from the World Nuclear Association’s summary of Uranium Enrichment that about 100,000-120,000 SWU (the separative work units used as a measure of enrichment capacity) is required to enrich the fuel for one year’s operation of a typical 1000 MWe light water reactor, and that gaseous diffusion requires about 2500 kWh per SWU, a simple calculation shows that enriching the fuel requires only about 3% of the energy the reactor can generate. That sounds like a good bargain to me.

Furthermore, gaseous diffusion is increasingly being replaced by the more advanced centrifuge enrichment process. For this process, the energy used to enrich fuel is only about 2% of that needed for gaseous diffusion. This reduces the energy required for this part of the fuel cycle to a very small fraction of a percent.

Another claim is that enrichment processes use chlorofluorocarbons (CFCs), or Freon, for cooling, and that these compounds are even more potent greenhouse gases than is carbon dioxide. While I am still in the process of researching this issue, I should note that the claim appears to be both specific to the gaseous diffusion process, and based on old practices. The transition from CFCs to less damaging coolants and the expected move from the gaseous diffusion to the centrifuge enrichment process make the basis for this claim outdated.

Other parts of the fuel cycle—mining and milling, conversion, and fuel fabrication, all require much smaller amounts of energy. (See, for example, an IAEA paper entitled, “Greenhouse gases and the nuclear fuel cycle: What emissions?”)

The one unknown sometimes cited in the allegations is that increasing use of nuclear power will exhaust high quality reserves, and that mining the lower quality reserves will take a lot more energy and result in a lot more land disruption.

The prediction of resources in the ground is an art that I don’t pretend to understand. However, I do know this. The exploration and full characterization of resources, be they oil or gas or coal or uranium, involves costs and effort. Mining companies expend the effort as it is needed. Reliable reviews, such as the well-known “Red Book” (Uranium 2007: Resources, Production and Demand) published by the Nuclear Energy Agency have concluded that there are sufficient resources for some time. An NEA Press Release summarizes the results of that study.

Even assuming that we must someday begin to use lower quality resources, the IAEA study shows that mining and milling currently requires only about 0.1% of the energy that the resulting nuclear fuel can generate. Therefore, the energy required for mining and milling would have to increase by perhaps a factor of 10 before we would get to the point that it seriously affected the net energy production from nuclear power.

It might be argued that I have not accounted for all steps of the nuclear fuel cycle. Frankly, I don’t have full data, and am seeking more information. However, it strikes me that spent fuel stored on site does not require much expenditure of energy, particularly when it is transferred to dry casks. A repository is like a mine, so I would assume the energy expenditures required to move fuel into a long-term repository (including the transportation to the repository) are roughly equivalent to the mining step. Reprocessing used fuel would surely be pretty energy intensive, but then you would end up with new fuel.

As far as greenhouse gas emissions are concerned, we should also keep in mind that enrichment doesn’t have to be fueled by coal, and mining doesn’t have to be fueled by petroleum products. We can envision someday replacing the current coal-fired plants that power enrichment facilities with nuclear power plants, and we can even envision small nuclear reactors built near mines (for uranium and other resources) to power mining operations. If and when we build reprocessing facilities, we can build them with or near nuclear power plants to meet their energy needs. We would still need energy to fuel these processes, but with that energy provided by nuclear power, we could reduce the greenhouse gas emissions from these steps.

So, as Paul Harvey used to say, “Now you know…the rest of the story.”

Tuesday, August 11, 2009

The Rest of the Story

One of my ongoing pet peeves is how often I see and hear letters to the editor, op-eds, speeches, interviews and even news articles on an issue relating to energy generation, distribution and use that makes bold assertions without any supplying any facts to back them up. Even though I've worked in the energy/nuclear energy sphere for over 30 years, I must confess that 1) I am certainly not an expert on all aspects of all energy sources, and 2) detailed numerical facts that I might have read or heard weeks or months or years ago somehow get lost in the nooks and crannies of my brain. Sometimes, I find I can recall just enough, or can do a back-of-the-envelope calculation with just enough accuracy to convince myself that something is wrong with what I'm reading or hearing, but my rough memories and calculations are barely enough to convince me, let alone to provide to anyone else to refute weak analyses.

If I can't accurately assess all that I read, I often wonder, what hope does the average person have? How does a person who never took years of math and physics and engineering gauge a claim that the nuclear fuel cycle uses more energy than it produces? (Yes, I've heard that one.) How does a person who is not an expert on transmission grids (count me in that group) assess a claim about what is or is not possible with an intermittent energy source like wind power?

In fact, I would extend this question even to energy experts. I am a nuclear engineer by training, but the assessment of the impacts of nuclear power plants requires far more than an understanding of the physical interactions and the heat transfer between the fuel and the coolant. It requires an understanding of biology, medicine and epidemiology to understand claims of health effects of radiation; it requires knowledge of natural resources and how they are discovered, characterized, and mined to figure out if we have sufficient resources and can extract them efficiently; it requires expertise in the environmental effects of the waste heat discharged into bodies of water. And it requires a similar understanding of the other energy sources to be able to assess the pros and cons of each and to develop an approach that best meets the needs of the country and the world with the least impact.

Perhaps my biggest hope for this blog is to try to find and assemble the arguments on all sides of all issues relating to nuclear power and alternative energy technologies. With a nod to the late Paul Harvey, I might call this "The Rest of the Story." As I stated, I'm not the expert on all these matters, but I hope to find and provide links to, or summaries of, arguments on both (or all) sides of each issue. My hope is to find good, quantitative, analytical arguments, both pro and con. In many cases, though, I don't have the definitive arguments on both sides. In those cases, I will present what I can find, and hope that viewers of this blog can help me fill in the missing arguments.

Some of the issues I'd like to tackle include:
• Health effects around nuclear power plants
• Safety of nuclear power plants
• The above question on net energy generation from nuclear power plants (and consequently, of carbon emissions)
• Water use by nuclear power plants
• Limitations of uranium resources
• Proliferation potential of nuclear power plants
• Cost of future nuclear power plants

For some of these issues, it is difficult to find information that is unbiased and reliable. This is particularly true for projections, such as future costs, where reasonable people can disagree on the extent to which past experience is applicable. As I develop some of these topics, I will hope for some inputs from people who have appropriate expertise.

In addition, from time to time, I hope to subject other energy sources to similar analysis. I have already provided an example of an allegation that wind may have potential health effects. Other issues have also been raised, particularly with respect to wind, but also with respect to other "renewable" energy sources. For wind alone, potential topics that I'd like to explore more include:

• Health effects of wind generators (as previously discussed)
• Potential impacts of wind generation on weather "downstream"
• Other environmental effects of wind generators (as bird and bat kills)
• Amount and distribution of wind generation capacity and/or storage capacity necessary to make wind a "baseload" resource
• Potential cost of such a resource
• Costs and other implications of offshore location of windmills
• Implications of widespread wind generation on grid management and technology
• Tracking of ongoing legislation and regulation restricting siting of windmills

Likewise, I hope to explore the issues associated with solar generators (land use, water use, costs, impacts on the grid, and generation of toxic byproducts of semiconductor fabrication are some I have heard about), of "clean coal" (where feasibility of the carbon extraction technology, costs, and potential long-term viability of the sequestration technologies are all important issues), of energy efficiency (how much is possible, what are the downsides--disposing of mercury light bulbs, buildup of radon and other toxic chemicals in well insulated rooms), and of ethanol (potential concerns about impact on food production, climatic effects of soil erosion).

For all of these, I will need outside help even more than on the nuclear topics, so I will be welcoming any experts who can supply credible information.

I will begin in the next week or so with one of the nuclear topics, and will bring up a topic from time to time as I gather the needed information. I will try to bring together the most credible resources I can find.

In the meantime, I hope to continue to cover other topics as well as items come to my attention.

Thursday, August 6, 2009

A Familiar Ring?

Does this have a familiar ring? A promising new technology is introduced with great fanfare about how it will solve all the problems of existing technologies. It will provide ample amounts of electric power. It is carbon- and pollution- free. We can get the costs down to reasonable levels. But…whoops, someone has identified some potential health risks. The emissions are below levels that are known to cause health effects, but people near these generators are suffering a variety of ailments.

Sounds like nuclear power plants, right? Wrong! This would be…wind! A recent article called “Are wind farms a health risk? US scientist identifies ‘wind turbine syndrome’” has hit the streets.

I was going to put this claim in the same category as claims of radiation effects from very low exposure levels, but I’m no expert on problems of the inner ear, so I’m not going to take a stand on this. Nor am I going to use it to wave over my head and say, “See, wind isn’t safe.” I profoundly believe that we need all energy-producing technologies. I was going to say that this is NWIMBYE (no wind in my backyard either). That may be an element, but if it is, it makes my concern about our energy future even more important.

The message of this article to me is yet another warning to be wary of claims of nirvana just around the corner from every new technology. People complain that nuclear was originally touted as being “too cheap to meter.” (That is not quite an accurate reading of history, but that is a story for another time. What is pertinent is that the public got the impression that was the case.) Going back still farther in time, people thought that automobiles were the answer to the…uh, pollution…from horses in the streets of cities. When there were just a few cars on the then unpaved roads of New York and Paris, no one worried about their emissions, their noise, traffic congestion, the migration of people from farms to cities, or the runoff from the paved streets that would have to be built. Going back yet further, people thought that petroleum would address the growing shortage of whale oil.

The message here is not to dismiss wind. It is to recognize that wind power will come with some cost, just as every technology does. Visceral vibratory vestibular disturbance (VVVD) may or may not turn out to be one of the costs, but whether or not it is, there are other concerns as well—bird kills, visual impact on scenic areas, effects on weather, etc. Just as there are concerns about carbon sequestration, solar collectors, hydroelectric dams, and every other form of energy. Even insulation and weather stripping has a downside, as it cuts down on air exchange and lets radon and toxic gases accumulate in buildings.

The message here is that the risks and costs need to be understood and addressed or managed. This is true of wind, it is true of nuclear power, and it is true of every other energy-producing technology. I’m convinced that the risks can be managed, but it will take an attitude shift on all sides.