Power generation and environment pollution

Environment pollution is an unsavoury byproduct of electric power generation. The volume of pollutants mostly containing carbon dioxide as gas is usually blown out to the atmosphere. In developed countries, where guidelines of pollution are specified in a number of countries, measures are adopted to reduce this atmospheric impurity to some extent. At present, along with power generation, both nuclear and thermal, these power plants contribute around 37 per cent of the total global emission of carbon dioxide into the atmosphere. It is estimated that the global power sector releases well over 10 giga tonnes of carbon dioxide to the atmosphere, which is around 37.0 per cent of total pollutants released to the environment. Apart from power generation, various industrial processes also add pollutants to the environment. Of the industrial establishments, the iron and steel industries contribute a significant portion of the overall pollutants released to the atmosphere. Environment pollution depends on the type of fuel being used for electric power generation, both as main fuel as well as powering all incorporated accessories related to the process. The fuels that are used for power generation are: Coal, oil, natural gas, biomass, hydroelectricity (water-fall), solar and wind.

Carbon capture sums up the indicated technology that substantially contributes to reducing carbon emission from most coal powered power plants. However, despite its potentials, this method has not been given widespread prominence in most commercial coal fired power plants, possibly to reduce nonproductive or negative investment for commercial considerations. This sector; that uses coal for power generation is by and large a major source of environment pollution. Based on studies carried out in 2010-11 in USA, the following figures represent the average figures of tonnes of carbon dioxide per GWh (Gigawatt hour) of power generated:

Coal- 888; fuel oil- 733; natural gas- 499; biomass- 45; nuclear- 29 and hydro-power- 26.

Clearly we see that among the power plants in the developed world, except China and Russia, hydroelectricity is the least polluting method of power generation, as the plant's prime mover is falling water; and not any gas or steam that turns the power generating turbines. For us in Bangladesh, the top priority should be to go for biomass, i.e., human and animal excreta as source of power production all across the country. Although nuclear power is close to a non-polluting source of power, it is by and large negated by an overwhelming risk of radiation leakage, profound fatal impact of which has been experienced recently in Japan, the most technologically advanced Asian country.

The writer is an engineer.

sam@dhakacom.com