By Sreekumar Raghavan
MUMBAI: The world is moving from super critical technology to ultra super critical technology to reduce carbon emissions in coal fired power plants. Sequestrian technology that can capture CO2 and bury it underground is also gaining momentum with many countries conducting R D to make it viable by 2020.
It is against this background that International Finance Corporation s (IFC) defence of the 4000 MW power project of Tata Power Co Ltd should be assessed. On Tuesday, major environmental groups had urged the World Bank to reconsider funding of the $4.2 bn ulta mega power project in Gujarat.
Responding to Commodity Online s story Why is Tata Power silent on Mundra Power Plant , Ruhee Dhar, Associate Sr Consultant of IFC provided us the following details. The (Mundra) project uses supercritical technology. This technology and the choice of unit sizes will help the project produce lower greenhouse gas emissions than regular coal fired power stations.
Supercritical technology will help the project achieve higher efficiency, which saves fuel and reduces greenhouse gas emissions.
The greenhouse gas emissions per kilowatt hour of energy generated will be about 750 grams of carbon dioxide per kWh, as compared to India s national average of 1,259 g CO2/ kWh for coal based power plants.
The world average is 919 g CO2/ kWh, while the average for OECD countries is 888 g CO2/ kWh. (Figures are for 2005.)
As compared to any other subcritical power plant in India, this project will avoid burning 1.7 million tonnes of coal per year, thus averting carbon emissions of 3.6 million tonnes per year, according to IFC s documents.
In China, a research project of Ultra Supercritical Coal Fired Power Generation Technology supported by the National 863 Program and undertaken jointly by the former State Power Corp., China Huaneng Group and China Power Investment Corporation, passed acceptance check recently.
Proponents of ultra supercritical technology argue that it is a superior technology when compared to supercritical technology. This terminology is used to differentiate the pressure and temperature conditions of the steam as compared to other types of coal plants with lower pressure and temperature conditions.
The ultra supercritical cycle is currently the most advanced steam power cycle that has been developed that is both economical and reliable, according to experts.
Environmentally, it is the cleanest commercially viable pulverized coal technology. The advantage of using ultra supercritical technology over other types of pulverized coal technology is that it takes less energy to convert the water used in the power generating process to steam. This means that less fuel needs to be burned to generate the same amount of power.
When compared to older technologies, the ultra supercritical power plants operate at increased efficiency and, as such, have considerably lower fuel costs.
For example, the average efficiency of an older coal plant is around 36 38% while a newer super critical plant can achieve an overall efficiency in the range of 43 45% and the most advanced ultra supercritical plant can achieve up to 50% efficiency, according information provided in various web sites.
These increases in plant efficiency can reduce CO2 emissions by a ratio of 2 to 1 (i.e. a one percentage point increase in efficiency reduces emissions by around two percent).
The promise of sequestration technology is that the large amount of carbon dioxide produced as a byproduct of coal fired electricity generation can be captured at the source and stored so that the amount of carbon dioxide released into the atmosphere is significantly reduced if not eliminated entirely.
Although existing sequestration technology is currently not considered to be commercially viable, capital investment is occurring to develop sequestration technology that can be utilized in a commercial way in US coal plants by the year 20206, according to the National Energy Technology Laboratory.
Whether Tata Power Co is using the latest technology available is still a debatable question. World Bank too has been endorsing Supercritical technology when the next generations of technologies to reduce carbon emissions are currently available.