The E-mail Commentary from Eco-Justice Ministries
The Apples and Oranges of Coal and Wind
For people in my home town of Denver -- and many, many other places -- coal trains are a familiar and frustrating experience.
Multiple times a day, mile-long trains wind through central Denver, carrying tons of Wyoming coal to power plants in Colorado Springs, Pueblo, and beyond. The trains are noisy (I can often hear them at night, even though we live miles away from the tracks), and inconvenient (they block major streets for extended periods of time).
Every one of those trains carries a toxic load of carbon that will soon be burned, releasing vast quantities of greenhouse gasses, damaging soot, and many other dangerous chemicals. The trains head south, over and over again, because the power plants have an ongoing demand for fuel, day in and day out. I feel tinges of grief, guilt and anger with every train that I see and hear, a complex mix of emotions about my complicity in a system that is degrading our planet.
On rare occasion, I see a train passing through Denver that is the antithesis of the much more frequent coal trains. The refreshing alternative is also a mile long, with identical cars, headed off to generate electricity. But instead of coal, these trains are carrying wind turbine blades.
It takes two rail cars to handle each of the massive blades -- long, sleek, white. Three blades will joined at the top of a tall tower, and dozens of towers form a wind farm. One of those long trains may carry enough blades to build a whole new farm. For many years to come, the turbines will spin slowly in the persistent wind, generating copious amounts of electricity without burning any fuel. I feel hope and joy each time I see one of these trains, because they represent a far more sustainable future for our society and our planet.
+ + + + +
A few months ago, a reader of Notes sent me a question about wind turbines. I think he shares my emotional delight with the prospects of wind power, but he has the integrity to question the facts about this allegedly clean energy. His email prompted me to do some research.
Larry asked: "how much carbon is released into the air as a result of building those enormous wind generators? Would it be reasonable to put the answer in terms of how long the wind turbine needs to produce electricity to balance out the initial carbon emissions?"
The fancy term behind Larry's question is "EROI," for "energy return on investment." It is a calculation that is done on all sorts of fuels. The other acronym that figures in is "LCA," for "life cycle assessment," which looks at the energy involved in the raw materials, construction, use and disposal of a facility. Both calculations can be complex, and involve lots of assumptions about how materials are extracted, processed and transported, but they give helpful figures.
I found the short answer to Larry's question in an "appropriate technology" source, and the news is good. They report, for wind turbines, "It has generally been found that energy pay back time is less than half a year." Some of their other calculations stretch it out just a bit longer. For the first 6 or 9 months that a turbine is working, it is paying back the energy costs to manufacture the blades, the electronics inside the turbine, the tall steel tower, the cement of the base, and the transportation of all those pieces. For the next 19 years or so, all of the clean energy is a bonus. The EROI reported by this source is 20.24 -- it generates 20 times more the energy than it took to build the machinery.
How does that measure up against coal? The comparison between wind power and fossil fuels is the proverbial "apples and oranges" of dissimilar objects. In such a case, it is important to be very clear about what is being measured and evaluated.
The reputable site "Skeptical Science" copies a graph showing the EROI for many forms of electrical generation -- nuclear, coal, hydropower, solar, etc. -- and wind is the best of them all. The article gives the same figure for a wind turbine that I'd seen elsewhere, that it produces 20 times more energy that it took to create it. I was very surprised, though, when I saw that coal was given a presentable EROI rating of about 8, which is better than solar.
This is where we get to apples, oranges and watermelon. As I tried to sort out some of those numbers, I was confused in the same way that I am when I see figures for the "miles per gallon" for an all-electric car that does not use any gas. One of the people who commented on the article (number 5, if you want to dig down for the details) says that the chart does a life cycle analysis on the generating facility and its operation, but not on the fuel that it uses! It looks at the energy expended to get coal to the power plant, but not the enormous amount of energy released when the coal is burned. (The same odd distortion shows up in comparisons of coal with solar and hydropower, which also generate electricity without burning fuel.) That seems to me like a rather stupid way to do the calculation, but I appears to be how it is done by the experts.
So, Larry, constructing wind power facilities is more than twice as efficient as building and running coal-fired generation. Beyond that, to actually generate electricity, the wind farm does not use any fuel, but the coal plant uses trainload after trainload of fossil fuels. The train with wind turbine blades goes through Denver once, the coal trains go to the power plant day after day after day.
Now, it is a bit more complicated than that. There are heated debates about how to figure in the "backup" power stations that are needed when the wind is not blowing. (Skeptical Science says wind still has good CO2 savings.)
The good folk at PeakOil.com work through some of the numbers, and conclude that we can't build massive numbers of wind turbines without using fossil fuels in the process. That's a challenge to the idea that we can rapidly transition away from all use of fossil fuels, but it doesn't contradict the idea that wind power is an environmentally valuable in the long run.
+ + + + +
For years, I have looked at those coal trains with disgust, and I have been delighted by the occasional trainload of wind turbine blades. It was a purely emotional reaction, rooted in noble sentiments about "clean" and "dirty" energy.
I'm grateful that Larry prodded me to look up some reputable details that confirm my gut feelings. I would have been grateful, even if the numbers showed coal and wind being about equal in their impact (which they are not!), because I need to be honest and informed about such important topics.
There's a saying in some of the debates about climate change these days, "You're entitled to your own opinions, but not to your own facts." When people of faith get involved in topics like efficiencies of electrical generation, we come with values and ethical norms that shape our opinions, but we still need to ground those in solid research and good facts.
With facts in hand, and with good ethical values, may we work hard to bring about a widespread and rapid change from fossil fuels to clean and renewable energy.
Eco-Justice Ministries * 400 S Williams St, Denver, CO 80209 * Home Page: www.eco-justice.org
Eco-Justice Ministries ended all programming on July 31, 2020. This site is an archive of writings and resources.
To contact a representative of the agency by e-mail, please use the contact form