We thank Mr. Hathaway for providing his analysis, and we certainly share his concern about the destruction associated with mountaintop removal mining. However, we find that his analysis doesn’t stand-up to close examination.
Our first objection concerns Mr. Hathaway’s basic premise that wind-powered generation will reduce the need for coal-fueled generation. The recent National Academies report on Environmental Impacts of Wind-Energy Projects compared U.S. Department of Energy projections for growth in electricity demand with projections for growth in wind generation. Between 2005 and 2020, annual U.S. electricity demand is projected to increase by more than a trillion kilowatt-hours (kWh). The projected increase in wind generation is expected to account for only 3.5% to 19% of this increase in total demand. In other words wind development may somewhat slow the growth in demand for electricity from traditional sources – but it will not reduce the demand for electricity from traditional sources.
Our second objection concerns Mr. Hathaway’s estimation of “18 acres of saved mountain top” per turbine. His calculations depend on a string of questionable data and assumptions.
• He relies on data published in Grist magazine and the Appalachian Voices newsletter as the basis for calculating that an acre of strip mining/ mountaintop removal yields 6,200 tons of coal. In contrast, EPA’s 2003 Draft Environmental Impact Statement on Mountaintop Mining/Valley Fill indicates that an average acre of mountaintop removal in West Virginia yields 10,000 tons of coal.*1
• He assumes that 100 MWh of wind generated electricity will displace 88 MWh of coal generated electricity – based on a report he submitted to the Virginia State Corporation Commission. We previously responded to this report, noting that it relies extensively on confidential and summary data that are not available or provided for independent review and evaluation. As we argued in our response, this lack of transparency is well outside the norm for either scientific assessment or public policy deliberation.*2
• He assumes that wind-generated electricity will only displace generation associated with coal that is mined through strip mining/mountaintop removal. According to the U.S. Energy Information Agency, more than 60% of coal mined in the Appalachian region is extracted from underground mines.
• His estimate of per-turbine electricity generation is based on 2.5 MW wind turbines, operating at a 35% capacity factor, with a lifespan of 30 years. There are no 2.5 MW turbines installed on central Appalachian ridges, most are 1.5 MW, and the largest are 2.0 MW. For turbines installed in the U.S. since 2000, the cumulative annual capacity factor (CF) in 2004 was 30% – and the average capacity factor (CF) of all the windplants in the eastern U.S. is less than 30%.*3 The rated operational lifetime for turbines installed to date in West Virginia is 20 years.*4
The combined effect of these questionable data and assumptions is an unrealistically high estimate of potential mountaintop removal offset. We have used original data sources and more-realistic assumptions to obtain a more-credible estimate.
• We rely on the above cited EPA estimate for West Virginia of 10,000 tons of coal per acre of area mined by mountaintop removal.
• We have less-optimistic expectations for turbine performance, based on current technology and actual observation. That is, our calculations are based on 2.0 MW turbines, with a capacity factor of 30% and an operational lifespan of 20 years.
• We calculate a mountaintop removal offset (MRO) of 22.8%, which is the product of and accounts for:
- Potential coal displacement, based on the percentage of Appalachian region electricity generated with coal (65.3%).*5
- Potential surface mine displacement, based on the percentage of Appalachian region coal extracted by surface mining (34.9%).*6
• Consistent with the Hathaway analysis and EIA statistics, we further assume that 1 ton of coal is equivalent to 2 MWh of electricity generation.*7
We apply the above assumptions to estimate a potential perturbine coalfield offset: (2.0 MW × 30% CF × 20 yr × 8760 hr/yr × 22.8% MRO) / (10,000 tonscoal/ acre × 2 Mwh/ton-coal) = 1.2 acres.
This 1.2 acre estimate is substantially less than the 40 to 50- acre estimate reported in the Wind Chill article or the 18-acre estimate subsequently provided by Mr. Hathaway.*8 Consider that modern turbines are installed on ridgelines at approximately 8 turbines per mile and that each wind energy project may clear an average of 3-5 acres of forest per turbine. The impact on wildlife and habitat due to forest fragmentation is an even larger issue when turbines and connecting roads are constructed on forested ridges, with a per turbine loss of 15 to 20 acres of interior forest habitat.*9
It is not our intention to compare the ecological impact of mountaintop removal coal mining and ridgeline wind energy development. It is our intention to provide some perspective. We should all be concerned about the environmental and human costs of mountaintop removal and other forms of coal mining. We suggest, however, that it is not in anyone’s interest to exaggerate the potential role of wind development in addressing this problem.
*1. U.S. EPA. 2003. Draft Programmatic Environmental Impact Statement for Mid-Atlantic Mountaintop Mining – Chapter 3, page III.J, 17 (see www.epa.gov/region3/mtntop/eis.htm)
*2. Mr. Hathaway’s submission to the Virginia State Corporation Commission and our submission in response are posted on the Virginia Wind website. (see www.vawind.org/Assets/Docs/Comments/ Hathaway_and_Jacobsen_070506.pdf and www.vawind.org/Assets/Docs/Comments/ Response_To_HNWD_Backdown_Study_080906.pdf)
*3. Energy Information Administration. 2004. Form EIA-860, Form EIA-906, and Form EIA-920 Databases.
*4. Det Norske Veritas. 2004. Type Approval of NM72C – Approval number A-642052-5 [NM72C is the model number of the 1.5-MW NEG Micon wind turbines installed at Mountaineer windplant in WV; Appendix 1 on p. 3 of the Approval indicates this turbine’s “Design life time” is “20 years”. See also www.wt-certification.dk/UK/Approved.htm]
*5. U.S. Environmental Protection Agency. 2006. eGRID2006: Emissions and Generation Resource Integrated Database (containing 2004 information) – available via: www.epa.gov/solar/egrid/index.htm (Region defined as MD, PA, VA, and WV.)
*6. www.eia.doe.gov/cneaf/coal/page/acr/table7.pdf (Region defined as MD, PA, VA, and WV.)
*8. Use of Mr. Hathaway’s 88% coal-displacement factor, instead of the 65.3% factor we apply, results in a 1.6 acre per turbine offset, as opposed to the 1.2 acre per turbine offset we calculate.
This article is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.
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