1. IEA Bioenergy Task 38 Case Study on the Greenhouse Gas Budgets of Peat Use for Energy in Ireland Kenneth Byrne and Sari Lappi Forest Ecosystem Research Group Department of Environmental Resource Management, University College Dublin

2. Objectives To improve our understanding of GHG emissions from undisturbed peatland, from peatland used for energy and from the different restoration approaches (e.g. forestry, restored wetland) when the peat extraction has ceased. To examine the potential of co-firing with biomass to reduce the GHG emissions from peat use for energy.

3. Energy use of peat in Ireland 4 million tonnes of milled peat is produced annually from over 20 000 hectares of peatland. Milled peat is used by four power plants for electricity production. Sod peat and briquettes are used as home heating fuel. Peat contributes :  6% of the total primary energy requirement  7.6% of the electricity used in Ireland Fossil fuel - renewable fuel???

4. Lifecycle of peat use for energy Extraction of peat Wetland development Forestry Dryland regeneration Combustion Undisturbed peatland Atmosphere CO 2 CH 4 Cutaway peatland ???

5. Lifecycle approach Lifecycle analysis for peat use for energy needed to be able to examine the total climate impact of peat energy and compare with other energy lifecycles. Peat energy lifecycle includes GHG-fluxes from:  Initial stage - undisturbed peatland  Harvesting of peat  Combustion  After-use of cutaway peatland. More information needed on GHG fluxes from production fields and different after-use management practices.

6. Role of peat in national GHG budget Energy use of peat generates 4000 Gg of CO 2 yr -1.  This represents 5.7% of the total GHG emissions in Ireland.  Emissions from peat combustion are the most significant in the whole lifecycle of peat use for energy. Emissions from peat production fields are highly uncertain.  Based on the available emissions factors, this would contribute 1 - 10 % of the total emissions from peat use for energy.

7. Potential to improve the GHG balance Replacement of old peat burning plants with new more efficient ones  38% reduction in the amount of CO 2 produced per electricity unit Carbon sequestration with after-use practices Combustion of biomass in addition to peat  Drying part of the peat prior combustion - lower moisture content of peat will lead to reduced emissions per electricity unit  Cofiring peat with biomass

8. Cofiring biomass in Edenderry power plant First of the three new peat burning plants - bubbling fluidised bed boiler with 38% efficiency Electricity production capacity 118 MW 1 million tonnes of peat burned annually - fuel supply agreement with Bord na Móna Annual CO 2 emissions around 900 000 tonnes CO 2 - emission reduction likely required by the emission trading scheme No major technical obstacles to replace part of the peat with biomass.

9. Potential for energy production by biomass (TJ)

10. Lifecycle of combustion of peat

11. Lifecycle of cofiring peat with recovered wood Atmosphere Undisturbed peatlandForest Harvesting Processing to wood products By-products, tree tops, branches, Conversion to electricity Preparation of peatland  Extraction of peat Building  Demolition Wood processing residues Processing to fuel Landfill After use of peatland  forestry  wetland  dryland Carbon flux to the atmosphere Carbon flux from the atmosphere or within the system Avoided process

12. Comparison of CO 2 emissions between peat combustion and cofiring with recovered wood 0 500000 1000000 Sole combustion of peat Cofiring 50000 tonnes recovered wood Cofiring 100000 tonnes recovered wood Cofiring 180000 tonnes recovered wood 20% moisture 10 % moisture CO 2 (t)

13. Emission reduction potential with cofiring peat and biomass 8-40 % reduction of CO 2 emissions with cofiring 50 000- 180 000 tonnes of recovered wood In short-term, maximum 15% emission reduction with cofiring recovered wood is possible Price of the biomass still high compared to fossil fuels - in future, the price may decrease due to increased price of carbon