Increasing coal power plant efficiency means burning less coal. So, in the past it was a way of cutting fuel costs, but now it is also a way to make significant cuts to CO2 emissions1.
Coal-fired power plant efficiency across different fleets varies widely; the current global average is 37.5 % (LHV, net), whereas state-of-the-art plants such as RDK8 in Germany and Waigaoqiao No. 3 in China achieve efficiencies of over 47%. This means that around 2 Gt of CO2 emissions could be saved annually if the gap between the average and the state-of-the-art was closed. Consequently, increasing power plant efficiency can be a real part of the solution enabling some countries to meet their Paris Agreement pledges.
There are several ways to increase plant efficiency, but the greatest results are achieved by increasing steam parameters: temperature and pressure. State-of-the-art plants currently use steam at 600 to 620°C but pushing beyond these temperatures has occupied researchers for almost two decades1. A massive jump in steam temperature to 700°C (760°C in the USA) is targeted to create advanced ultrasupercritical power plants (AUSC) and R&D programmes are ongoing in USA, China, Japan, India and until recently in Europe.
Despite intensive research around the world since the late 1990s, we are yet to see the first AUSC plant in operation. There are various reasons for this. Some are technical – to push steam parameters higher requires new materials such as nickel-based alloys for the hottest areas of the plant and improved steels for less demanding ones. These are expensive and need to be tested intensively before they can be used in a commercial plant. Other reasons include a lack of relevant government policies and funding. However, all the above may change, and the world’s first AUSC plant may be built in India, somewhere in the next decade, as the country seems to be establishing a new climate pathway for balancing its energy priorities. This is likely to include AUSC technology as a central part, as evident from the recent National AUSC Conference on Advanced Ultra-Supercritical Technology. The event held on 30 – 31 October 2019 in the Indian city of Hyderabad was jointly organised by the Indian AUSC programme consortium of NTPC Limited (the major Indian power corporation), BHEL (the domestic power plant equipment manufacturer) and IGCAR (Indira Gandhi Centre of Atomic Research, which brings materials expertise). The Indian AUSC programme has been enabled and supported throughout by the office of the Principal Scientific Adviser to the Government of India.
The conference was attended by about 200 delegates, both international and from India. It gave a very good overview of India’s ambitious plan to build AUSC plant and also featured detailed domestic research on advanced materials. All the presentations suggest that the programme has made significant progress. The international speakers, myself included, covered global efficiency trends, ways of increasing efficiency and the outcomes so far from AUSC programmes in the EU, USA, Japan and China. As I heard from the Indian presenters, the presence of most of the nickel alloy suppliers at the meeting gave confidence in their undertaking as the quantity of materials required for their 800 MW technology demonstration have never yet been produced.
The Indian AUSC programme was initiated as part of its National Action Plan on Climate Change. Its vision of an AUSC plant is also somewhat linked to the concept of a methanol economy. Consequently, India wants to undertake carbon capture and utilisation (CCU) R&D and put up a pilot plant along with the AUSC demonstration to cover the larger picture. This is impressive as India has also significantly increased its share of renewables in the energy mix and plans to increase it further to 175,000 MW by 2022.
With coal still being deployed worldwide as a means of ensuring energy access, fuel diversity and energy security, it is good to know that countries such as India, are actively pursuing the development of new, cleaner technologies. I will be looking closely at the Indian programme of development and will include it in my report on efficiency improvement of coal power plants, which should be available around June 2020.
References:
- Lockwood T (2018), Coal may be Jurassic, but technology is not. Only Natural Energy, Available at: https://www.onlynaturalenergy.com/coal-may-be-jurassic-but-technology-is-not/
