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FEATURE STORY: Cleaning Coal - Stunning Tianjin Energy Project is Testing the World’s most Cutting-edge Technologies by Cutting Emissions from Coal-fired Power Plants
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Executives from the world’s biggest coal miners and burners have been filling rooms at Tianjin’s high-end hotels lately. They’ve been coming here in droves to visit a unique coal power plant, GreenGen. Opening a year behind schedule, the 250 megawatt (MW) IGCC power plant in the city’s Binhai district will generate electricity by burning coal. But, crucially, the plant will capture most of the harmful carbon dioxide (CO2) emissions generated by burning coal. The technology will be vital in China’s battle to reduce chronic air pollution blanketing cities like Beijing and Tianjin in recent months. 
 
Unique to Tianjin, this power project will emit near zero emissions.

Located in Binhai New Area, Tianjin, the USD 1.5 billion project is run by Chinese energy giant Huaneng (Tianjin) IGCC Company Limited. With plans to add a 400 MW demonstration IGCC power plant will be ready by 2020. 
 
IGCC stands for an integrated gasification combined-cycle, a process of turning coal and other carbon based fuels into gas and then removing impurities from the gas before it’s combusted to generate power. “With GreenGen, China shows that the world’s leading coal-consuming nation can also be the world’s leading clean coal provider,” Gregory H Boyce, CEO of coal mining firm Peabody, told media after his visit to Tianjin. His firm, which has a 6% stake in GreenGen, is clearly learning a lot from the project.
 
Sung Ming, China head of the Clean Air Task Force and a coal gasification expert, believes the key to clean air is clean coal. “You do that by gasifying it, making coal into a gas, either above or below ground. This is the technology that will change China.” Sung believes that stricter enforcement of a regulation requiring sulphur removal technology in coal fired factories will also be vital.
 
While GreenGen began generating electricity for the Chinese grid in the summer of 2012, at full 650 MW capacity. GreenGen will be the world’s largest near-zero emissions coal plant with carbon capture and storage technology. “GreenGen will utilise  Chinese technology to burn coal much more efficiently than conventional power plants, with harmful CO2 emissions safely stored deep underground,” explains Deborah Seligsohn, principal advisor at the World Resources Institute’s China Climate and Energy Program. Another innovation: the plant’s cooling system will use seawater instead of fresh water. Rather than pumping it into the ground for deep-earth storage, the CO2 captured at the GreenGen site will be converted for fuel, through a system of enhanced oil recovery for CO2 reuse.
 
The project is part of the Tianjin Lingang Industrial Zone Circular Economy Plan, and has a host of national energy majors on board, as well as the world’ s largest coal company. The latter US-based Peabody, is joined by some of China's largest utility and coal companies including power generator companies China Datang Corporation, China Huadian Corporation, the China Guodian Corporation and the China Power Investment Corporation.  Also on board: coal miners the Shenhua Group, the China National Coal Group and the State Development and Investment Corporation.
 
Construction work on the first stage of GreenGen began in 2009, but the investment decisions required for such an expensive project date back to 2004, when China Huaneng Group (CHNG), a state controlled power generator, announced it would develop a new generation of power plants run on clean coal, matching other similar ambitious projects, such as FutureGen in the U.S. and ZeroGen in Australia. The Australian government has been attempting to form a coalition of governments and corporations to develop 20 industrial scale CCS projects worldwide in the next ten years.
 
However, as proven by GreenGen, China has done most of the running on carbon capture and storage (CCS), overhauling the European Union (EU), which has been funding research into CCS since the 1990s. The EU, which has made CCS central to its efforts to cut carbon emissions, has promised to build 12 CCS demonstration plants of at least 250 MW capacity by 2015.
The bloc however, mired in pressing financial problems, has watched China take the lead. 
 
Export Ambitions
 
GreenGen has garnered international and national attention as the Tianjin plant plans to prove that coal can be a clean source of energy, with an admittedly complex cleaning system. The hope is the low emissions technology can then be rolled out across China, and exported. Aside from solving its own obvious environmental problems as the world’s leading polluter, China stands to become a world leader in CCS technology, with all the export earnings that come with that. Dr. John Topper, managing director of the IEA Clean Coal Centre, says the Tianjin project is part of a “deliberate move, quietly encouraged by the authorities, to get into a position where China owns its own intellectual property [for CCS]… A significant number of Chinese universities and institutions are running research programs related to CCS while some of the leading companies are starting to build pilot plants at real-scale and planning demonstration units of their own.” 
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Questions Remain
 
“Despite enthusiasm for GreenGen, China has no policy framework or laws in place to encourage the use of CCS technology,” says Dr. Topper. Doubting China’s ability to lead, the Sussex Energy Group, which brings together researchers at the University of Sussex in the UK with Tsinghua University in China in a recent research paper stated: “The possibility that China might take the lead here seems unrealistic. In this power-hungry country, most utilities are put off by the 25% loss in thermal efficiency required to power the carbon capture equipment.” 
 
Though Chinese engineers are experimenting with tools and equipment to dispose of some of the plant’s carbon emissions underground, the government has grown alarmed at how much water it takes to operate. “The program to build more such plants has been curtailed,” said Jennifer Turner, director of the China Environment Forum at the Woodrow Wilson International Centre for Scholars in Washington, D.C.
 
The need to develop more efficient ways to use coal, and to lower requirements for water, is keener in China than any other nation. China’s economic development agency projects the demand for coal will exceed five billion tons this year, more than three times production in the United States. More than 70% of all of China’s energy is produced by coal, and coal use is set to double here by 2020, it’s essential that China finds a proven way to produce coal-fired energy without the pollution associated with it. That means there’s an awful lot at stake in Tianjin. Clearly, we can expect a lot more coal bosses and environmental experts coming to visit the city. 
 
Carbon Capture Storage: How it works
 
altThere are three techniques for carbon capture. One of those methods separates carbon dioxide from gasified coal to produce hydrogen and CO2 before combustion in ‘pre-combustion capture’ (i.e. before the coal is burned). Pre-combustion comes from an integrated gasification combined-cycle (IGCC) technology (already used in making fertilisers and chemicals) that turns coal into gas, with impurities removed and pollutants converted into re-usable by-products. Excess heat from the combustion and generation is then passed to a steam cycle, similarly to a combined-cycle gas turbine. 
 
Alternatively the coal is scrubbed from flue gases ‘post-combustion’ or after burning. The most understood method, post-combustion capture, where the CO2 is removed after combustion of the fossil fuel – is a potential game changer since it can be retrospectively applied to existing coal fired power plants. 
 
A third approach is to burn the coal in an oxygen environment. In Oxy-fuel combustion, the fuel is burned in oxygen instead of air. To limit the flame temperatures to appropriate levels, cooled flue gas is re-circulated and injected into the combustion chamber. The result is an almost pure CO2 stream that can be transported to the sequestration site and stored. 
 
The World Coal Association calculates research and improved technology could eventually cut the cost of CCS from a current USD 80 - 120 per tonne of CO2 stored to USD 40 - 60 per tonne. The final stage of the CCS chain is the transportation and storage of the CO2 in deep underground storage locations. CO2 has to be buried at up to 1,000 metres underground in order to ensure sufficient pressure to keep it liquid, while also being capped with an impermeable clay covering. 
 

By Mark Gao
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