Renewable energy: Avoid constructing wind farms on peat

Journal name:
Nature
Volume:
489,
Page:
33
Date published:
DOI:
doi:10.1038/489033d
Published online

Scotland's government is planning to build large-scale wind farms to reduce carbon emissions from electricity production, some of which could be situated on peatlands. We contend that wind farms on peatlands will probably not reduce emissions, unlike those on mineral soils.

Wind farms are often located in upland areas because most of these are windy, distant from residential areas and of low agricultural value. Peatlands are prevalent in UK uplands and are richer in carbon than mineral soils because peats are formed from decomposing wet vegetable matter. Peatlands therefore have a higher net carbon loss when drained for construction.

The UK wind industry uses a method we and our colleagues developed to estimate carbon emissions (D. R. Nayak et al. Mires Peat 4, 9; 2010). On this basis, and assuming current emission factors for electricity generation, our previous work argued that most peatland sites could save on net emissions if peat is not drained and if sites are restored after construction.

However, emissions factors are likely to drop significantly in the future owing to reduced fossil-fuel use in electricity generation (see go.nature.com/lnowou). As a result, peatland sites would be less likely to generate a reduction in carbon emissions, even with careful management. Unless the volume of peat excavated can be significantly reduced relative to energy output, we suggest that construction of wind farms on non-degraded peats should always be avoided.

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Affiliations

  1. University of Aberdeen, UK.

    • Jo Smith,
    • Dali Rani Nayak &
    • Pete Smith

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  1. Report this comment #53732

    Peter Cary said:

    On behalf of Jo Smith:

    Construction of windfarms on degraded peats can save carbon

    The headline linked to our correspondence on 6th September (2012), "Avoid constructing windfarms on peat", has resulted in misunderstanding of the intended message. With good management, our calculations1 show that carbon savings are possible for windfarms constructed on many peat sites; it is developments on non-degraded peats that should be avoided. After 2025, assuming low-carbon electricity generation, windfarms on non-degraded peats are unlikely to give net carbon benefit and technological advances would be needed to achieve savings.

    The Scottish Government's Carbon-Calculator2 assesses carbon losses at any given site. It is widely used by the industry to determine how to manage a site for maximum carbon benefit; the Scottish Government are leading the way by including this in planning applications for windfarms over 50MW. Carbon-payback-time is calculated by comparing these losses to savings made by replacing fossil fuels. As electricity generation becomes decarbonised, savings will fall because wind replaces less carbon-intense electricity generation. The calculations provided by the Carbon-Calculator should account for this fall in savings by using the emission factor for replaced energy production, averaged over the windfarm life. Calculations using emission factors at time of consent underestimate carbon-payback-time by a factor of 0.6 in 2010, falling to 0.4 by 2030. Predictions of fuel-mix used for electricity generation are uncertain, but errors introduced by not using reduced emission factors are likely to be greater than this uncertainty.

    If consent for windfarms on non-degraded peats is not given, some suggest there will be reduced decarbonisation. We assert that windfarms constructed on non-degraded peats contribute apparent, but not actual decarbonisation. It is likely that other developments will replace development on non-degraded peats, so genuinely counteracting any reductions. Onshore windfarms have great potential to reduce carbon emissions from electricity generation, but this will only be true if developments on non-degraded peats are avoided.

    Jo Smith, Dali Nayak, Pete Smith

    1Nayak, D.R., Miller, D., Nolan, A., Smith, P., Smith, J.U., 2010. Calculating carbon budgets of windfarms on Scottish peatlands. Mires & Peat 4, Article 09, http://www.mires-and-peat.net/, ISSN 1819-754X

    2The Scottish Government, 2012. Wind farm savings on peatlands. http://www.scotland.gov.uk/Topics/Business-Industry/Energy/Energy-sources/19185/17852-1/CSavings (accessed 22/05/12).

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