Clean coal - which Tuas Power will use as a feedstock at its upcoming $2 billion clean coal/biomass Tuas Multi-Utilities Complex (TMUC) on Jurong Island - seems an oxymoron. But given technology such as ultra-supercritical coal-firing plants, as well as carbon-capture facilities being developed by its new owner, China Huaneng, Singapore’s first coal-firing station coming on stream in 2012 seems in good hands, environmentally speaking.
Dispelling preconceptions of choking fumes and soot spewing from its chimney stacks, Huaneng’s Yuhuan coal-firing plant, which our group of Singapore journalists visited, is spotlessly clean. Enhancing its “green-ness”, the plant, along the south-east coast of Zhejiang, is nestled amid rice and vegetable fields with bei shan, mian hai - or mountains behind and the sea in front - which is considered good Feng Shui.
More critically, pardon the pun, Yuhuan’s ultra-supercritical power plant has boilers which can operate at higher temperatures and have greater thermal efficiency; therefore it uses less coal to produce the electricity. The plant is considered one of the cleanest, most efficient and advanced worldwide.
With 4,000-megawatt (MW) capacity, the Yuhuan station is also Huaneng’s biggest. It is 50 percent bigger than the 2,670MW Tuas Power (TP), which Huaneng acquired from Temasek Holdings for $4.2 billion in 2008, and about a fifth larger than Singapore’s largest genco, the 3,300MW Senoko Energy.
Capitalising on its superior efficiency, the Yuhuan facility is also Huaneng’s biggest electricity generator of all its power plants in China. Yuhuan produced a whopping 16.9 billion kilowatt hours of electricity in the first three quarters of this year, or almost 9 percent of Huaneng’s total output in that period, latest figures show.
Yuhuan is an integral part of Huaneng’s “green action” drive to cut its greenhouse emissions, which is important given that 85 percent of the group’s power stations are coal-firing. It has also embarked on developing energy alternatives such as wind, solar and biomass. A Huaneng official says, “We have an aggressive plan to produce about 35 percent of our electricity from clean energy by 2020.”
On the coal-firing front, Huaneng is working hard to reduce its carbon dioxide (CO2) emissions by developing technology such as the ultra-supercritical plants employed at Yuhuan, and also through carbon-capture pilot projects like its Shidongku 2 station, just outside Shanghai.
TP’s TMUC project, which was based on Japanese technology, was already at an advanced development stage when Huaneng first came into the picture. Nevertheless, the new Chinese owner has not shied from getting involved.
“Huaneng has extensive experience which TP can tap as it develops the Tembusu project,” a Huaneng official said.
For instance, Huaneng is getting Chinese manufacturers, including boiler makers, involved in TMUC “as costs are lower than in Japan”, one official said. Tapping its connections, it is also sourcing low-ash coal from Southeast Asia for the project. TP’s Singapore engineers have also been to the Chinese coal plants, such as at Shidongku, to learn how Huaneng handles its coal.
At Yuhuan, for example, barges unload coal at the plant’s jetty from which it is transported via a fully enclosed conveyor system to covered storage silos before use.
“This is exactly what we will do in Tuas as well,” remarks a TP official. Additionally, TMUC’s use of carbon-neutral biomass feedstock, such as palm kernel, will help reduce the plant’s emissions to a level comparable with those of oil-fired plants.
Yuhuan has China’s first 1,000MW ultra-supercritical pressure boilers which, by operating at 600° Celsius steam temperatures, result in a net thermal efficiency of around 46 percent, or 6 percent more than the earlier-generation supercritical plants.
“This also means that we burn about 6 percent less coal to produce the same electricity output,” said a Yuhuan official, adding that the station is planning to add another two super-ultracritical plants to the existing four, with each “possibly even going up to 1,200MW capacity”.
Parallel to this, at its 2,400MW Shidongku 2 station on Shanghai’s outskirts, Huaneng has developed a pilot facility for carbon capture (that is, CC without the S, as in storage). With its 100,000 tonnes per annum, the CC plant is currently the largest in the world. This was an expansion of its first Beijing CC pilot plant, which captures just 3,000 tonnes of CO2 per annum.
“Beijing and Shanghai were chosen for the carbon-capture pilot plants as they were the most polluted cities,” said Chen Xi, a director at TP’s Beijing office.
Still, with most of China’s coal plants still focusing on desulphurisation processes, CO2 capture is still relatively new, admits Cao Xuegao, Shidongku’s vice-plant manager.
The 150 million yuan (S$29 million) Shidongku CC plant occupies an area of 6,000 square metres and is divided into carbon-capture and refining sections, with the latter processing the carbon into 99.5 percent pure CO2 for sale to the food and beverage industry (for products such as carbonated drinks).
But the CC pilot plant - which barely captures 2 per cent of the CO2 produced by the Shindongku 2 power station - is not commercially viable yet, concedes Mr Cao.
It is a costly process with the carbon capture costing about 300-350 yuan per tonne. But as the CC plant has been barely operational for 10 months, “we are looking to just break even and not make profits at this stage,” he adds.
Huaneng is now working with Xian Thermal Research Institute on how to optimise the CC process to try to further lower costs. This will likely involve a combination of a scaling-up in capacity as well as through technology advances.
“The Beijing and Shidongku CC pilot projects will provide the basis for the study of large-scale CO2 capture and geological storage technologies,” Mr Cao says.
Still, given that carbon capture is still a work-in-progress and not commercially viable yet, it is unlikely that Huaneng will be able to introduce the technology at its Singapore TMUC project for a while yet.
Undoubtedly, however, lessons learnt will eventually find their way here.
