Impact of Today’s Coal-Fired Power Stations on Rainfall and Climate Change

A novel 15-year global study has shown that present-day coal-fired power stations generate more ultrafine dust particles compared to road vehicles and could also alter and readjust rainfall distributions.

This study has demonstrated that filtration systems on the latest coal-fired power stations are the largest source of ultrafine particles (UFPs) and are found to have a substantial influence on climate in many ways.

Previously, road vehicles were regarded as the chief source for the emission of tiny particles in urban regions, leading to harmful impact on the environment and health.

But long-term analyses performed by Professor Wolfgang Junkermann (Karlsruhe Institute of Technology (KIT), Germany) and Professor Jorg Hacker (Airborne Research Australia, South Australia)—both associated with Flinders University—have shown that modern coal-fired power stations are the main source responsible for the variation in the regional climate.

Using the exhaust gas filtering technology, the scientists have reported, in the Bulletin of the American Meteorological Society, that enormous amounts of UFPs are obviously emitted by coal-fired power stations. Following are the important outcomes of this long-term study:

• UFPs can affect human health
• When compared to urban road vehicles, modern coal-fired power stations discharge more UFPs
• UFPs with high concentrations can be transferred in layers to several kilometers and can lead to localized “particle events” (drastic spikes in short-term particle concentrations on the ground) at a long distance from their source
• UFPs can impact rainfall distribution on scales from local to regional by increasing the condensation nuclei count.

The study has also indicated that UFP concentrations have been found to constantly increase with the commissioning of the present-day coal-fired power stations in many places across the globe.

For the measurement flights in Australia, Europe, as well as Mexico and Inner Mongolia, the scientists used two very strange small research aircraft, namely the world’s most thoroughly instrumented motorglider in Australia and a “trike” designed in Germany—known to be the smallest manned research aircraft in the world.

The flying laboratories are supplied with highly sensitive instruments and sensors that can measure dust particles, temperature, wind, trace gases, humidity, and energy balances.

Our two research aircraft are particularly suitable to follow the plumes from the smoke stacks downwind for hundreds of kilometres and study their behaviour in great detail.

Jorg Hacker, Professor, Airborne Research Australia

Later, the research team integrated these data with meteorological observations and used dispersion and transport models to determine their origin.

In this way, we found that fossil power stations have for many years become the strongest individual sources of ultrafine particles worldwide. They massively influence meteorological processes and may cause extreme weather events, including intensive rain events. By redistributing rainfall events, this can lead to drier than usual conditions in some places and to unusually heavy and persistent strong rainfall elsewhere.

Hacker, Professor, Airborne Research Australia.

This study has reported that UFPs with a diameter of <100 nm have a major impact on environmental processes, with the potential to affect the properties of precipitation and clouds.

The UFP offer surfaces for chemical reactions in the atmosphere or may influence the properties of clouds and precipitation.

Wolfgang Junkermann, Professor, Karlsruhe Institute of Technology.

Forest fires, volcanic eruptions, and dust storms produce fine particles in the open air but generally not in the range of nanometers.

The research team studied the existence, distribution, and transport processes of UFPs by flying the aircraft close to or downwind of the coal-fired power stations and over remote regions where very low UFP concentrations have previously been measured at the ground level.

In particular, the scientists discovered that in areas with clear precipitation trends such as inland Western Australia and Queensland, UFP concentrations have been continuously increasing and are possibly caused by the emissions from the coal-fired power stations and refineries.

Exhaust gas cleaning takes place under conditions that are optimal for the new formation of particles. Ammonia is added to the exhaust gases in order to convert nitrogen oxides into harmless water and nitrogen.

Wolfgang Junkermann, Professor, Karlsruhe Institute of Technology.

However, ammonia has been found to be present in the air at a correct mixing ratio for the formation of particles, leading to high concentrations of the exhaust gas. The scientists have discovered that extremely small particles, after being emitted from smokestacks at a height of 200–300 m, typically extend over several kilometers according to the climate and weather conditions in the atmosphere.