I Introduction

1 Preliminary remarks

The German government has decided to further expand the use of energy from renewable sources and has set ambitious targets for the reduction of CO₂ emissions. In addition to transport and buildings, this predominantly affects the field of electricity and heat generation. As the share of energy from renewables in power generation increases, the use of other sources of energy will decline gradually. Nevertheless, as a result of the great volatility of the renewables and a lack of the industrial-scale electricity storage facilities which would be needed, the German power supply industry will not be able to do without electricity generation from fossil fuels in conventional plants in the foreseeable future. Conventional power plants are indispensable if the security of electricity and heat supply is to be maintained, especially at the times when generation from renewable energy sources can only make a minor contribution or are prevented from doing so at all by natural circumstances such as the time of day or night and the weather. As a step towards security of supply and maintenance of the competitiveness of Germany as a location for industry, therefore, a balanced fuel mix in conventional power generation is to be maintained. This also involves the use of hard coal and lignite as one of the important pillars in generation. In that context, electricity generation from coal takes place in accordance with environmental standards which are enshrined in law, using the best available techniques (BAT) to reduce emissions, including those of mercury.

The best available techniques are defined as those technologies or modes of operation of a power plant which, when considered in both technical and commercial terms, effectively con-tribute to the achievement of a generally high level of protection for the environment as a whole.

Correspondingly suitable technologies therefore have to be selected, taking account of the circumstances of the power plant concerned in terms of systems and fuel. The state of the art in the reduction of mercury emissions is to this extent characterized not by any particular technology, but rather by solutions related to individual cases within the BAT bandwidths. For a holistic optimization of the separation process, the entire process chain at the power plant and all environmental media affected (air, water and soil) are to be considered. This is intended to preclude the use of particular separation technologies merely to shift the burden between different media. The air and water paths and the power plant by-products and waste are therefore equally the subject of observation.

2 Framework conditions

The striving for a high degree of environmental compatibility is a permanent entrepreneurial task. The essential framework conditions are stipulated by the legislature. The statutory stipula-tion of emission limits first and foremost serves to provide for the protection of health and the environment.

The airborne contaminant emissions from German power plants are above all governed by the Federal Pollution Control Act (BImSchG), and within that context in particular by the Ordinance on Large Combustion Plants (13th Federal Pollution Control Ordinance – 13. BImSchV). The latter contains requirements for emission limits (in some cases as annual and daily averages) and for emission measurement and evaluation of the results.

Germany already has strict mercury emission limits, and is one of the pioneers within the EU and globally. The stipulated limits for mercury, last reviewed in 2013, are currently 30 µg/Nm³ in the waste gas (daily average). From 2019 onwards, it will also be necessary to comply with an annual average of 10 µg/Nm³.

A large proportion of mercury is already captured and removed from the flue gas with the technologies currently deployed. Since 1990, the mercury emissions in Germany have been reduced by approx. 68 %. The coal-fired power plants have played a major part in that reduction. The concentrations measured in the outside air in Germany are significantly below the permissible immission levels. According to the Federal Ministry of the Environment (BMUB – Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit), mercury immissions, even in the vicinity of coal-fired power plants, are between 1 and 2 ng/Nm³ (0.002 µg/Nm³). They are therefore considerably below the immission level for outside air of 50 ng/Nm³ (0.05 µg/Nm³) which is recommended by the World Health Organization (WHO).

Pan-European specifications to be implemented in national pollution control law are established by the EU Industrial Emissions Directive. At present, the emission requirements in that directive for large combustion plants are being reviewed on the European level within the context of the BREF-LCP process (Best available techniques Reference document, LCP: Large Combustion Plants). The Integrated Pollution Prevention and Control (IPPC) Bureau in Seville which was appointed by the EU Commission to perform that review has submitted a final draft of the BREF-LCP. Following adoption of the updated emission limits by the member states in the European committees, publication in the EU Official Journal is expected in early 2017.

For the first time, this process is also to provide an emission requirement for mercury, mandatory throughout the EU, in the form of bandwidths. The final draft of the BREF-LCP proposes emission bandwidths (annual averages) for existing large combustion plants with a rated thermal input > 300 MWth in the range of

In the next step, the final emission bandwidths have to be transposed into limits by the authorities or legislatures of the individual member states. Compliance with the emission bandwidths set out in the new BREF-LCP by large combustion plants is required by four years after their publication in the Official Journal of the European Union – i.e. prospectively by 2021 – at the latest.

Optimisation of mercury capture

With their coal-fired power plants, the German power plant operators make an important con-tribution to ensuring reliable and competitive energy supply. They are conscious of their responsibility to use the best available techniques to reduce emissions in their plants. This also applies to the capture of mercury.

Independently of the BREF-LCP process and the proposed reduction of limits in Germany, the companies represented in VGB PowerTech have been conducting intensive research for several years now into opportunities for optimization and new technical methods of mercury separation. Owing to the complex interrelationships with mercury, the research projects and development work are time-consuming and various aspects of the plant and apparatus required have not as yet been finally clarified. Suitable technologies with trials and validation followed by implementation on an industrial scale with design and approval planning will not be available in the near future.

With the VGB Initiative “Hg^cap”, VGB PowerTech and the power plant operators wish to con-tribute to putting the debate on a more objective footing and to achieving an appropriate im-plementation of the results of the BREF-LCP process.

In the following declaration by the “Hg^cap” Initiative, the power plant operators in the European technical association VGB document their intention to carry on this work and to intensify it and report on it under the umbrella of the VGB.

3 VGB Initiative Hg^cap

Mercury Emissions from Coal-fired Power Plants - VGB Initiative Hg^cap

The use of fossil sources of energy, especially hard coal and lignite, in the generation of electricity and heat will, on a partnership basis with energy from renewable sources, continue to make an important contribution to secure and competitive energy supply in Germany.

The operators of fossil fuelled power plants grouped together in VGB PowerTech commit themselves to improving the capture of the mercury released from the fuel. In doing so, they can draw on extensive experience and have already taken a first important step in this direction:

The mercury emissions from the coal-fired power plants have already been reduced by over 60 % in the last 25 years as a result of improved separation techniques.

In order to promote a further reduction in mercury emissions, the operators grouped together in the VGB have embarked on important work in the research into and testing of new separation techniques. This work is to be continued and intensified. The common focal areas of the further efforts to reduce mercury emissions include the following:

• Analysis of all technologies, including new technologies, for separation of the mercury from the flue gas and the waste water of the power plants.
• Assessment of the technologies in terms of technical framework conditions specific to plant and modes of operation.
• Assessment of the technologies in terms of continued unrestricted usability of the power plant by-products as raw materials and construction materials in the economic cycle.
• Assessment of the technologies in terms of the recycling and disposal of the waste created.
• Adaptation of various technologies to the specific conditions of plants within the context of re-search and development.

With the aim of improved mercury capture, the companies and VGB PowerTech will ensure the mutual exchange of knowledge and experience and such exchange with scientific and political institutions. At the same time, the public reporting of these activities will be intensified.

In that context, VGB PowerTech and the companies will work towards putting the public debate on industrial mercury emissions onto an objective footing. With regard to the further development of the applicable legal conditions, the companies and VGB PowerTech demand a reasonable stipulation of limits on the basis of the European requirements and a reasonable time frame for the establishment of suitable and efficient processes.