Project Number 308

Determination of CH4 and N2O Emissions from Power Plants by Measurements as well as Measurements of the Proportion of Elemental and Oxidised Mercury in Flue Gases

Concerning the third emissions trading period for greenhouse gases it is discussed to include further greenhouse gases in the trading system, e.g. methane (CH ₄ ) and nitrous oxide (N ₂ O). According to the EPRTR Regulation further the release of certain pollutants from installations, e.g. power plant sites, has to be reported annually, if specified mass thresholds are exceeded.

Fossil fuelled power plants emit CH ₄ and N ₂ O in small amounts. Emission factors used by the authorities up to now are significantly higher than the (few) existing measuring results. Regarding emissions trading and other considerations concerning measures against climate change - as well as in the context with the annually published EPRTR data - this could lead to an overestimation of the power plants’ contributions, resulting in unrealistic emissions reductions obligations.

To avoid this, it is necessary to carry out continuous CH ₄ and N ₂ O emission measurements to determine realistic emissions data for these components. The measurements shall be conducted at four different power plant types: hard coal dry furnace and slag-tap furnace, pulverized lignite firing and a combined cycle power plant.

The abatement of the environmental pollution caused by mercury (Hg) has been identified by the EC Commission as an important task. Already in the Commission’s Community Strategy concerning mercury from 28 January 2005 coal combustion was identified as a main source for mercury releases. The mercury input into the soil caused by power plants’ flue gases in Germany is limited by a limit value for the Hg deposition. Presumably also in other member states the mercury input from power plants into the environment could be limited in licensing procedures in the near future.

The results of dispersion calculations for Hg can be very different. The reason for this is that - depending on the chemical speciation of the flue gas mercury (elemental or oxidised) - very different deposition velocities have to be used in these calculations. In licensing procedures in Germany strictly the much higher value for oxidised Hg has to be used up to now. As there are some hints from VGB members that a significant share of Hg in power plant flue gases is elemental, parallel Hg measurements shall be carried out in the frame of this research project to determine realistic values for the share of the Hg speciation. Through this it can be avoided that power plants are made responsible for too high Hg inputs into the soil.

The project will be realised until May 2008 by ANECO Institut für Umweltschutz GmbH & Co., Mönchengladbach/Germany, headed by Klaus Schröder. The General Committee “ Environmental Protection, Safety at Work and Chemistry ” supports the investigations.