The Clean Coal Centre was awarded a cost-recovery based contract by the US State Department to organise this one-day workshop on coal power plant efficiency and emissions improvement in South Africa to support implementation of mercury emissions reduction in the country. South Africa recently signed the Minamata convention. Signatories are free to set their own means to reduce emissions.
The 12th in the Clean Coal Centre’s series of Mercury Emissions Control workshops was held over the following three days at the same location.
US State Department Workshop
Approximately 50 people participated in the workshop on efficiency and emissions improvement.
Session A – Welcome
The welcoming addresses were given by Dr Lesley Sloss of the IEA Clean Coal Centre.
Mr Geoff Schadrack of the Energy Office of the US Embassy, highlighted the importance of the workshop.
Mr Obed Baloyi of the South African Department of the Environment and Agriculture, also welcomed its value in contributing to the debate on energy supply and its environmental implications in the region.
Barry MacColl of Eskom, provided scene setting (without slides) by outlining the Energy landscape of South Africa. South Africa’s electricity supply situation had moved back from under-capacity, with load shedding, to a position since last year of excess capacity. More capacity was coming on line, with the units at Medupi and Kusile gradually commissioning, but there was uncertainty in future demand, which might decrease further or increase again. This was making planning difficult. Issues include whether to close older units, whether to build nuclear plants, uncertainties in costs of new plants (coal and nuclear), effect on the system and Eskom of addition of more renewables by independent power producers (IPPs), the structure of the electricity market. Decisions were needed urgently on these and other issues.
Session B – Reports developed for the workshop
Two reports: Energy versus emissions and Challenges for the coal-using energy sector were produced by Lesley Sloss and Colin Henderson and circulated in advance of the meeting. Presentations were made by the two authors on these topics. A key objective of this meeting was to obtain information to update and refine these reports to inform the US State Department of current developments.
Session C – Towards cleaner coal power in Africa
Ebrahim Patel, of Eskom, presented on the practical considerations in implementing mercury control at Eskom’s power plants. He included an update on the status and plans for flue gas desulphurisation (FGD) units at the supercritical Kusile and Medupi plants under construction. NOx emissions from current units would be controlled sufficiently to meet required levels, using combustion measures, although the 2020 date for compliance with the new limits on both NOx and SO2 will be missed by a number of units. Promotion of in-country skills was important. FGD would probably be used at Kendal in the future.
Stephen Niksa described the i-POG software that Niksa Associates has developed for UN Environment Programme (UNEP) for initial rapid estimation of mercury emissions. He demonstrated it, showing its ease of use and accuracy as a first estimate for assessing technology options.
Dirk Porbatzki, of Uniper, described multi-pollutant control in coal-fired power plants. Among issues that he highlighted was that it is possible for mercury to emerge in the gypsum by-product of wet FGD unless the design ensures that it is taken out with the waste water. Gypsum is a major component of plasterboard, used by the construction industry.
Session D – Alternative options for South African coal
This session was about underground gasification of coal (UCG). UCG has been of considerable interest in South Africa as a means of exploiting high ash coals effectively and economically.
Shaun Pershad, of Eskom, described Eskom’s experience to date. Progress was suspended currently for non-technical reasons.
Johan Brand, used his UCG Integrated gasification combined cycle (IGCC) IPP project, currently held up by the permitting process, to illustrate the future potential for the technology in South Africa. He showed favourable costs and was waiting only for permitting processes to be improved, so that he could progress to implementation.
Session E – Potential roadmaps for South Africa
Wojciech Jozewicz, of Arcadis, who works closely with UNEP, described capacity building projects in Vietnam and Bangladesh. These included equipment supply and training in-country.
There was then an open discussion, led by Lesley Sloss, to define the way forward for coal in Southern Africa to meet energy needs while minimising environmental impacts, including mercury emissions. These discussions were targeted at filling in in gaps in our knowledge of the local and regional situation and the observations made by the participants will be incorporated into the final reports to the US State Department.
Seventy people took part in the workshop, with presenters from many countries, including a number from China. A summary of the presentations follows. Registered delegates will be able to access all presentations via the workshop website within the next few weeks.
Session 1 – Welcome to South Africa
The workshop was opened by Lesley Sloss of IEA CCC. She included a resumé of the previous day’s US State Department event.
Han Shui, Chief Engineer, National Energy Administration, China, presented on Ultra-low emissions policy development in China. This discussed the general strategy of the implementation of measures to meet the tight emissions limits for NOx, SO2 and dust that are now set in China.
Session 2 – The challenge for emissions reductions in growing economies
Xie QieYe, of Eppei, China, described the Status quo and future prospects of multi-pollutants and mercury emissions control technologies in China. Several examples of the technical measures being installed to meet the new strict emissions limits were described in detail.
Kristie Langerman, of Eskom, presented on the Mercury emissions from South Africa’s coal-fired power stations. The emissions that the speaker showed were estimates only at this stage. Retrofitting of some of the ESP-equipped plants with bag filters was ongoing. A national cap on mercury may be more appropriate than emission limits for South Africa.
Edward Pakpahan, of the Ministry of Environment, Indonesia, described Mercury emissions from coal combustion in Indonesia. Increasing boiler efficiency by fine-tuning of excess air levels could give a worthwhile improvement in coal burn and emissions.
There was also an additional paper given by Anton Purnomo of the Basel Convention Centre in Indonesia summarising results from a fine combustion tuning project at a 3,400 MW plant in the country which demonstrated cost savings of around $2million/y for the power plant.
Wojciech Jozewicz, of Arcadis, described Minamata-related activities in Southeast Asia. This was similar to his presentation in Session E of the US DoS workshop, described earlier.
Session 3 – Emissions from coal combustion
Josh Charles, of Lehigh University, USA, spoke on Emissions reduction from coal-fired power plants by operational improvements. Additives in the FGD can reduce mercury re-emission to <1 µg/m3 average without using activated carbon, so is a lower-cost method.
Peter Nelson, of MacQuarrie University, NSW, Australia, spoke on Ambient atmospheric mercury in the vicinity of large coal-fired power stations. He used an interesting technique, employing ground level ambient SO2 data to indicate plume descent and demonstrated no correlation with measured mercury.
Yufeng Duan, of Southeast University, China, presented on the Characteristics of distribution, migration and emission of trace elements in a 660 MW coal-fired plant. This gave data on different areas of the plant that had been monitored.
Yongchun Zhao, of Huazong University, China, described the Emission of mercury in a 35 MW (thermal) industrial-scale oxyfuel combustion power plant. In one of his slides, he also outlined China’s oxyfuel upscaling plans.
Session 4 – Emissions from coal combustion under new EU legislation
Andreas Wecker, of VGB PowerTech, Germany, spoke on the Challenges for European power plant operators for mercury reduction after completion of the BREF-LCP process. The complex BREF process was elucidated in his very useful presentation.
Alfons Kather, of Hamburg University of Technology, Germany, described Expert opinion on BAT-associated emission levels for mercury emissions to air from existing lignite-fired power plants in the LCP BREF review process. He showed how, in his view, the EU BAT Reference development process for setting mercury emissions ranges had resulted in values for the lower limits which were available for member states to set that would be impossible to meet in existing lignite units.
Session 5 – Monitoring and measurement
Eric Prestbo, of Tekran, USA, spoke on Environmental mercury measurement: fundamentals, history, experience and current status in the USA for research and monitoring of air and emissions. He gave a description of analytical methods with examples of coal mercury compositions.
Nikolay Mashyanov, of Lumex, Russia, described Determination of the total mercury and mercury thermospecies in coal. This presentation showed that speciation of mercury could be identified by thermo-analysis.
Deborah Padwater, of SICK, Germany, described Continuous mercury emissions measurement at concentrations lower than 10 µg/m3. There is no certified continuous mercury measuring system to cover the 1-2.5 µg/m3 range, so it will not be available for when BREF (Best available technologies reference document) is adopted.
Milena Horvat, Josef Stefan Institute, Slovenia, described Metrology of oxidised mercury. This was about ensuring uniformity of measurements and measurement standards for mercury.
Session 6 – Emission control with sorbents
Jamie Fessenden, Carbotcorp, USA, presented on Cost effective reduction of mercury using powdered activated carbon injection. ACI costs $-6 $/kW in capital. There have been significant advances in the technology.
Jost Wendt, University of Utah, USA, described the Evaluation of MinPlus sorbent for mercury capture. The sorbent is a by-product from the paper production industry and contains limestone, lime, aluminosilicate and silica.
Sheila Glesmann, ADA Technologies, USA spoke on Mercury compliance in North America using powdered activated carbo. ACI does not adversely affect ash utilisation. ACI into FGD can mop up re-emission of mercury (a known issue).
Yunying Zhang, Huazhong University, China, described Mercury removal from flue gas by modified clay minerals. Data presented included the average mercury content of Chinese coal (0.195 µg/g coal – similar to US coals.
Yongchun Zhao, Huazhong University, China, described Research on mercury emissions and control during coal combustion in HIST-SKLCC. A magnetic sorbent could be recovered magnetically from the fly ash for reactivation and re-use. EHe expected the 30 µg/m3 limit for mercury in China to be tightened after the ultra-low emission programme retrofits (NOx, SO2, dust) had been completed.
Session 7 – Emissions control – emerging systems
Olw Petzoldt, W L Gore, Germany, described Multi-pollutant control by fixed sorbent systems. A solid polymer catalyst was used to convert SO2 to H2SO4, while mercury was caught by chemi-sorption.
Graham Dickson, Celec, Canada, described Mercury emissions control by packed bed scrubbers. This technique was developed for capturing mercury emitted from gold roasting.
John Meier, of Nalco, USA, described Control of mercury emissions – alternative methods. This system, said to be much lower cost than ACI, was developed for adding to semi-dry scrubbers.
Yufeng Duan, Southeast University, China, presented on the Effects of NH4Br additive in coal on mercury transformation and removal during coal combustion. A 6 kWth CFBC was used and the coal was a Guizhou anthracite.
Ida Masoomi, Stuttgart University, Germany, presented on Effect of various precipitating agents at differing operational parameters on Hg partitioning in wet limestone FGD. Precipitating agents were used to reduce mercury re-emission from wet FGD scrubbers.
Lesley Sloss, IEA CCC, UK, presented on Emerging markets for multi-pollutant control systems. The presentation was a shorter version of her comprehensive webinar on the topic, given recently.
After the MEC workshop there was an associated, but separate, meeting to outline the nature and function of the UNEP Coal Partnership. The partnership sets up projects in Minamata countries to build capability in measuring and monitoring of mercury to facilitate compliance.
Gunnar Futsaeter, UN Environment, Switzerland, gave an update to the Minamata Convention.
Wojciech Jozewicz, of Arcadis, USA, spoke with an update on the UN Environment partnership – current and proposed projects in Vietnam and Bangladesh and gave a Summary of the BAT/BEP document.
The Coal Partnership will be evolving as the Minamata moves towards ratification later this year. Members of the partnership will soon be asked to provide more details of their work and capabilities in order to help create a database of expertise which can be used by countries wishing to establish demonstration and full-scale projects as they move towards compliance. More details on this, along with other updates on the partnership work, will be circulated to partners soon. More details on the UNEP Coal Partnership can be found at http://web.unep.org/chemicalsandwaste/global-mercury-partnership/mercury-control-coal-combustion