Improving the efficiency of coal-fired plants is one of the toughest challenges in the electricity industry today and it is being carried out using state-of-the-art technology. Adi Roesch highlights coal’s role in a post-COP21 world and spotlights recent case studies
Utilities around the world are modernizing their coal-fired fleets
Long before leaders of the industrialized world gathered last November for the COP21 conference where they negotiated the landmark Paris Agreement, the global coal power industry had already been working to maintain its important position in the world’s energy supply mix while also supporting the greenhouse gas reduction goals of COP21.
However, since the coal power sector has long been viewed by critics as being a source of industrial greenhouse gases, can the industry play a serious role in helping to address climate change? The answer is yes, according to the World Coal Association (WCA) and the growing number of utilities around the world that are investing millions of dollars in modernizing their existing fleets of older coal-fired power plants (or seeking to build new units) to dramatically reduce their emissions.
After all, coal is forecasted to remain the world’s second largest energy source through 2030, and an even more critical source of electricity in developing economies such as in Central and Eastern Europe and Asia – including India and China – as well as in the Middle East and Africa. The ability of nations to meet the emissions goals set out in the Paris COP21 agreement, while meeting growing demands for electricity, will depend on the ability of fossil fuel-powered plants such as coal to deliver power more flexibly, responsively and cleanly.
The WCA is letting the numbers speak for themselves in explaining why coal will continue to be a critical enabler for economic development worldwide. It provides 41 per cent of the world’s electricity. By 2040, installed power generation capacity from coal will reach 2843 GW, up from 1805 GW today. On its website, the WCA notes that each nation will choose an energy mix that best meets its needs. For many nations, including the industrializing and urbanizing countries of Asia and Central and Eastern Europe, coal has been identified as a growing fuel source that is a logical low-cost baseload power choice and integral to their economic growth.
In high growth countries like China and India, new high efficiency coal plants are also coming online. There is a real need to ensure that these new plants, along with the massive installed base of older units, operate with maximum efficiency and minimum emissions throughout their lifetime. For those continuing to choose coal as part of their supply mix, increasing the current average global efficiency rate of coal-fired power plants from 33 per cent to 40 per cent could immediately cut two gigatonnes of CO2 emissions alone, while allowing affordable energy for economic development, according to the WCA.
In an ironic twist, the WCA envisions a growing supporting role for the coal-power sector in expanding the integration of renewables around the world. Because of the intermittency of renewable energy sources such as wind and solar, utilities are increasingly turning to natural gas-fuelled generation to help stabilize the grid. The WCA notes the coal power sector could have a similar future.
However, just as utilities needed to upgrade their natural gas combined-cycle stations with more flexible generation equipment to keep pace with grid changes, existing coal plants also need to be modernized with more flexible, cleaner generation equipment that can respond to peaking power needs and other demands if the industry wants to maintain its position as a key baseload power source in a lower carbon world.
Emissions regulation compliance
Improving the efficiency of coal-fired plants is one of the toughest challenges in the electricity industry today. Plant technology is typically more mature (50 per cent of active plants in Europe are more than 25 years old), systems are highly complex and average efficiency rates are low.
In Central-Eastern Europe, the Czech Republic’s energy company ČEZ Group is one such utility that has been making significant investments in upgrading its fleet of older coal-fired power plants to improve their performance and comply with regional European Union emissions reduction regulations, including the European Directive that required power sources producing more than 50 MW to cut their NOx emissions levels down to 200 mg/Nm3 by 2016.
GE recently completed advanced boiler modernization projects at ČEZ’s coal-fired Elektrárna Počerady plant and the coal-fired Mĕlník I plant, operated by Energotrans, a power and engineering company fully controlled by ČEZ. These upgrades reduced the power plants’ nitrogen oxide (NOx) emissions by 60 per cent, enabling the stations to supply power and heat to households and industries in compliance with EU emissions standards.
“Refurbishing the Mĕlník I power plant guarantees Prague, Neratovice and Mĕlník reliable long-term deliveries of heat generated in an environmentally sound manner,” says Miroslav Krpec, chief executive of Energotrans. “Citizens of Prague and the Central Bohemian Region quickly benefited from cleaner air as we brought the modernized equipment into operation in stages throughout 2015.”
GE modernized four 200 MW pulverized coal boilers, originally supplied by Czech engineering group Vitkovice, at the Počerady plant in the northwestern part of the country, as well as six Vitkovice-supplied pulverized coal boilers at the 1089 MW Mĕlník I plant.
“Over a period of only six days, at the Počerady power plant we gradually increased the output of each boiler from 130 MW to 190 MW to ensure everything worked properly. Each boiler passed demanding stress tests, and we are very satisfied with the performance of the new equipment and the project execution of the GE team,” says Jiří Kulhánek, chief executive of Elektrárna Počerady.
Nitrogen oxides are by-products of combustion processes. It is crucial for operators to control NOx emissions because not only is NOx a major air pollutant by itself, but it also reacts in the atmosphere to form ozone – the primary constituent of smog – and acid rain. Ozone remains a significant air pollution problem worldwide, with many people continuing to be exposed to unhealthy levels in the air they breathe.
ČEZ is not alone, as other utilities across Europe and in other regions of the world are seeking to deploy the latest technologies to help modernize their own fleets of aging coal-fired power stations. Operators now have access to the technologies and services that can significantly reduce coal plant emissions. GE’s own NOx removal system efficiency rates are up to 92 per cent, SOx removal efficiency rates are up to 99.5 per cent and mercury reduction is up to 90 per cent.
Steam turbine upgrades
Also in the Central and Eastern Europe region, in July GE’s Power Services announced an agreement to modernize a Zamech-made turbine-generator set at Veolia Energia Poznań ZEC SA, a 275 MW district heating plant.
GE gained its global capabilities to service non-GE steam turbine equipment through its acquisition of Alstom Power’s thermal services business in November 2015. “This project will help the station to operate more efficiently as we want to strengthen our position in a very competitive environment,” says Jan Pic, member of the board and operational director of Veolia Energia Poznań ZEC.
The Veolia Energia Poznań station features one 65 MW Zamech unit and two 105 MW Zamech units. Unit 3’s output will be increased by up to 6 MW (the extra power will be sent to the local grid) while turbine efficiency will be increased by up to 6 per cent.
Mĕlník I plant
Additionally, to improve the turbine’s operational flexibility, during periods when there is no demand for electrical power, the operator will be able to disconnect the low-pressure (LP) part of the steam turbine while it is in full district heating mode. This will allow the operator to use thermal power for the preheating of district heating water only.
Poland-based Veolia, which is one of the leading service providers in the areas of energy, water and wastewater as well as waste management, operates in 74 towns and cities, including Warsaw, Łódź and Poznań. The company is the largest private operator of district heating networks across the country. It is also Poland’s third largest cogeneration plant operator. The steam turbine modernization outage at the Veolia Energia Poznań station is expected to start in May 2017. Commissioning of the upgraded equipment is scheduled for August 2017.
Veolia Karolin Poznań power plant
Asia and beyond
In other countries such as India, which recently adopted stricter NOx regulations, utilities will need to invest in both hardware and software solutions to help them increase the efficiency of their aging coal-fired power plants to comply with regional emissions regulations. China also is expected to adopt new NOx reduction rules in the next couple of years, according to Scott Bolick, head of software strategy and product management for GE Power.
In the US, where the current administration has been seeking to dramatically curtail power plant emissions, a number of utilities have chosen to make significant investments to modernize their coal-fired stations rather than retire or replace them in favour of other fuel sources.
As with other energy sectors, the coal-fired power industry been undergoing a digital transformation of its existing and new facilities to achieve greater condition monitoring and performance outcomes.
In a recent GE survey of over 100 power generation executives, 94 per cent said they believe the internet and improved analytics will transform their industry in the coming years.
With this future outlook in mind, in 2016 GE Power unveiled its new Digital Power Plant for Steam software system, which is powered by Predix, the company’s cloud-based platform that powers the Industrial Internet.
Digital Power Plant for Steam is a suite of technologies that help coal-fired power plants improve performance and efficiency, thus reducing greenhouse gas emissions. The software is expected to play a significant role in helping utilities support their respective nations’ COP21 greenhouse gas emissions goals.
The software platform can be installed in all new plants as well as existing plants commissioned in the past 25 years, covering both GE and non-GE equipment.
While coal-fired plants generate 40 per cent of the world’s electricity, GE’s new Digital Power Plant software can reduce CO2 emissions from those plants by 3 per cent. With GE’s asset performance management, advanced controls and cyber security software, the Digital Power Plant for Steam interprets data drawn from sensors across the power plant, highlights key factors that may affect performance (such as fuel quality, plant aging and ambient conditions) and takes appropriate action through a closed loop control system.
The new software can also reduce fuel consumption by 67,000 tonnes of coal per year – with the same MW of output – based on a 1000 MW power plant.
In a key technology development, earlier this year GE acquired NeuCo, a Boston-based supplier of plant optimization technologies for the coal power industry. NeuCo’s boiler optimization software (also known as BoilerOpt) was a perfect fit for GE’s new Digital Power Plant for Steam platform as Predix Operational Optimization for Boilers.
Among its benefits, the software monitors and seeks to improve the mix of fuel and air in the combustion process, which is critical to both output and emissions. Too much fuel in the mix may lead to higher emissions. Too little air may lead to ineffective combustion and output.
The WCA asserts that a low-emission technology pathway for coal is required to achieve the emissions reduction targets set out by COP21. The global coal-power industry is demonstrating its long-term commitment to invest in the latest power generating technology and digital solutions for both existing and new coal plants to help countries around the world reach their respective energy supply and Paris Agreement goals.
Adi Roesch is Central European General Manager for GE’s Power Services business