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APGTF workshop on power generation (coal, gas and biomass) under increasingly stringent emission regulations

The workshop took place on 6 December in London, at the IET building on the Strand overlooking Victoria Embankment gardens and the River Thames – a pleasant view during the breaks. It opened with a joint presentation by Steve Mills (from UK Department of Business, Energy and Industrial Strategy, BEIS) and Nicola Leeds (UK Department of Environment, Food and Rural Affairs, DEFRA) giving the UK government perspective. Steve talked about the Energy Trilemma and the need for a low cost, sustainable and reliable energy system in the UK, as well as energy security. There are currently only 9 coal-fired power plants operating, and these are scheduled to close by 2025. One reason why new coal plants are not being built is the need to be ‘carbon capture ready’. From an energy security viewpoint there is concern that new capacity is not coming on-stream quickly enough. Plants will need to invest in CO2 capture by 2025 or close. The Energy Innovation spend will double to £400 million per year by 2021 (as announced in the Autumn budget) but this is across the whole energy field and not just power generation. Nicola said that EU legislation on emission limits will be brought into UK law after Brexit. But DEFRA seeks views on what should remain or change – so now is your chance to comment! Consultation on the EU directive on Medium Combustion Plants (MCP) is still open (closes 8 Feb 2017). The MCP directive (which specifies emission limits for plants of 1-50 MW thermal rated input) needs to be transposed into UK law before the UK leaves the EU. Richard Chase from the Environment Agency discussed the BREF (best available technologies reference) document for large combustion plants. He was the UK representative at the BREF discussions. The document will be statutory, unlike the previous 2006 one. There are different emission limits for new and existing plants, and different limits for coal and gas plants, in some cases. He pointed out the need to read the document carefully, as “the devil is in the detail”. For example, if a boiler that is converted to biomass is unsuitable for (selective catalytic reduction control of NOx) SCR then you will not need to fit SCR. John Henderson, also from the Environment Agency, discussed planning and permitting requirements for power plants. New build plants (over 300 MW) will need to be carbon capture ready, including having a suitable CO2 storage site. The planning and permitting requirements for new build plants are very complex. For example, there are the current eels and the new fish pass regulations to be met. Funding is also a problem.

After being given the UK Government’s perspective, Roger Brandwood from Uniper gave a utility’s viewpoint on the emission limits. This included the Industrial Emissions Directive (IED), Large Combustion Plants (LCP) Directive, LCP BREF and MCP directive. The LCP BREF is including additional emission limits for HCl, HF and mercury that coal-fired power plants will need to meet (besides NOx, SO2 and particulate matter). There is also concern over CO2 emissions with the targets set by BEIS. There are other driving forces, besides environmental concerns, influencing the decisions of power plant operators; these include security of supply and Brexit. Mike Wheeler (Ramboll) than gave an energy consultant’s viewpoint – an international versus a UK perspective. Planned coal plants are mainly in Asia and the Pacific regions. Some new coal plants are planned in Germany but it is not certain whether they will proceed. In the UK, we have the situation where no new power plants can be built without government approval. Mike looked at one of the National Grid’s scenarios for the future energy mix in the UK (all 4 scenarios can be found on the National Grid (NG) website), and discussed whether there was a limited role for coal, and the possible roles for gas, biomass and CCS (none for CCS in the NG scenario). The UK government’s intervention in the energy market has often had unintentional consequences.

The first session after lunch, looked at some control technologies for meeting the emission limits. David Smith from Doosan Babcock believes that the future for coal-fired plants is most likely to be ultrasupercritical (USC) which, because of its higher efficiency, has lower emissions. Net plant efficiency of USC plants is typically 2% higher than supercritical plants. State-of-the-art emission control technologies include low NOx burners (now designed to fire a wider range of coals), SCR, and FGD (Circoclean system). Oxyfuel and postcombustion control of CO2 were mentioned. In addition, PM2.5 and mercury are starting to be regulated and their control (e.g. by wet ESP for PM2.5) needs to be considered. Biomass conversion as an emissions control technology was discussed by Graham Welford (Doosan Babcock). Biomass (as virgin wood) is more expensive than coal, but emissions of SOx and NOx are lower due to its lower sulphur and nitrogen contents. Sawdust in North America can be burnt at the sawmill as waste. Instead, it can be made into pellets and burned at Drax to produce power. If CCS is installed, then emissions of CO2 will be negative. The biomass conversion at Lynemouth (3 x 140 MW) is installing low NOx burners that are bespoke to biomass. A more technical presentation by Edward Naylor (Fraser-Nash) discussed the role of modelling in understanding emissions from biomass. This included the use of CFD modelling to see whether a plant can meet Article 50 of the 2010/75/EU (IED) directive.

Jon Gibbins (University of Sheffield) looked at the suitability of CCS plants to meet future emission limits. We still need 1 or 2 demonstrations on coal-fired power plants to prove the technology. Oxyfuel does not appear in the LCP BREF as it is an emerging technology. The last presentation, from Michael Nash (Johnson Matthey Technology), described different catalytic emission control technologies for coal and gas power plants, including honeycomb and plate catalysts, SCR systems, and pellets. A co-benefit with SCR is that mercury is oxidised and absorbed in the wet FGD system. Advanced mercury catalysts are also available. One challenge is measuring mercury oxidation over the SCR catalyst. A protocol for testing the oxidation is just coming out in the USA.

The meeting concluded with a lively discussion. For example, it was pointed out how complicated it is for power operators to operate in the UK, and that subsidies for renewables is impacting the market for everyone. Should we be following other countries and build new power plants? In the Middle East, Egypt and Dubai are building coal power plants, partly for energy security reasons. Larger cleaner plants are at a disadvantage compared less cleaner ones, such as small plants. The UK is reaching the point of grid instability. There is a need to bring engineers into policy making. The market does not look after energy security – this is up to the government.

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