By David Ahlfeld Gazette Contributing Writer
Where is the land that produces your food? For many of us, some of what we eat comes from local sources. We have our own gardens or know the farmers who grow our food; we can visit the land where it’s raised. But where is the land that produces our electricity? For a few, rooftop solar photovoltaic panels or small solar farms provide electricity for household needs. But for most of us, our electricity is derived from coal or uranium mines or from mined natural gas. Though we use electricity locally, the environmental impact of its production occurs more in distant landscapes than in our own.
Do we have a choice? Can we make our electricity locally, just as we do our food? Yes, we can. Solar and wind provide obvious local, renewable sources. Hydropower, biomass and biofuels might also be considered. But the choice comes with a challenge: A system of local, renewable electricity production will make a substantial mark on our local landscape.
There is little doubt that our society will need electricity for the foreseeable future. Electricity is a wonderful form of energy delivery. It is easily moved around on wires, and it runs all sorts of marvelous machines. We may super-insulate our homes to minimize heating needs and use human power for much of our travel needs, but most of us will still need or want refrigeration, lights, gadget-power and, maybe, a fan for hot summer weather. Our workplaces and the production of the food and goods we consume also use electricity. With the growing interest in electric cars, demand for electricity is likely to increase. Electricity should be used as frugally and efficiently as possible, but in our modern society it has become a fundamental human need.
In New England, most electricity is generated by burning coal or natural gas or by splitting uranium atoms for nuclear power. These energy sources are mined from the earth, transported to our region and used to manufacture electricity. These highly concentrated forms of primary energy can make electricity at power plants that occupy relatively small land areas. In contrast, wind, solar and other renewable sources are diffuse. Making electricity from wind turbines and solar panels requires that energy be collected over large areas of land.
As an example of the challenges to a local, renewable electricity system, consider Vermont Yankee, the nuclear power plant in Vernon, Vt. How would its electricity generation, enough to power about one million homes, be replaced if it were to close permanently? If Vermont Yankee were replaced with solar farms they would cover a land area of about 17,000 acres. To give an idea of what that would look like, the recently proposed solar farm for a closed landfill in Amherst would cover 30 acres. Replacing Vermont Yankee would require about 570 solar farms of that size.
Or consider wind turbines. There is a new wind turbine in Charlemont that is nearly 300 feet tall. About 2000 turbines of that size, spread over tens of thousands of acres, would be needed to make up for the power generated by Vermont Yankee. (See below for information about acreage calculations.) Hydropower and biomass might also be part of the mix, but studies indicate that the sustainable energy available from these sources is relatively small.
Of course, any actual system would include some combination of wind, solar, other renewables and conservation, along with some means for electricity storage. But the inconvenient truth is that if we are serious about replacing nuclear and fossil-fuel electricity generation with locally generated, renewable- source electricity, then renewable-energy installations will be prominent on the landscape. Rather than “not in my backyard,” the cliché will become “yes, in everyone’s backyard.” The alternative is to continue to run our lights, refrigerators and computers with electricity from West Virginia coal mines and mountain tops, Pennsylvania natural gas hydro-fracking operations or renewable projects (and associated transmission lines) that occupy someone else’s landscape. Locally produced electricity is a visible way to take responsibility for the energy we use.
Some people may consider local, renewable-energy installations as despoiling their landscape. There is another perspective. Many of us travel past beautiful farmland in our area and say with some pride, “my food is grown there.” I look forward to a time when we can view the wind turbines on the ridge or the solar farms covering a hillside and say, with that same pride, “my electricity is generated there.”
Calculating acreage requirements
The Vermont Yankee nuclear power plant has a capacity of 605 megawatts (MW). These calculations show how much land would be required to replace the plant with electricity generated with wind turbines or solar panels.
To begin with, we have to take into account the actual production of each of these types of power sources in comparison to their capacity. (This is a bit like comparing the gas mileage on the sticker of a new car to the performance you get under real-life conditions.) Energy specialists use “capacity factors” to express this difference as the ratio of actual production to capacity. Expressed as percentages, these factors are often assumed to be about 90 percent for nuclear, 30 percent for wind and 20 percent for solar. The latter two are low because neither wind nor solar radiation are available all the time.
To match Vermont Yankee’s output, here’s how much land would be needed for wind or solar power. We start by multiplying Vermont Yankee’s capacity of 605 MW by 90 percent, for an actual production level of 544.5 MW. To scale up wind or solar generation to that equivalent, we divide that number by each source’s capacity factor, then multiply by the land area needed per megawatt. A reasonable estimate of land area for solar is 6.3 acres for each MW of production. For wind, the total land area accounts for the spacing of wind turbines in an array. Depending on spacing and other factors, a wind farm may occupy a total area of 30 or more acres per MW. The result of these calculations indicates a land area of approximately 17,000 acres for solar power and at least 54,000 acres for wind generation to replace Vermont Yankee.
David Ahlfeld is a professor of civil and environmental engineering at the University of Massachusetts, Amherst.
Earth Matters, written by staff and associates of the Hitchcock Center for the Environment at 525 South Pleasant St., Amherst, appears every other week. For more information, call 413-256-6006, or write to us.Click here to return to full list of Earth Matters articles.