Coal has been a key factor in the industrial revolution that shaped our Western societies from 1700 on. It is still an important and secure source of energy with proven exploitable reserves amounting to 150 years at current consumption rate.
On the other hand, coal is also the fossil fuel with the highest carbon content and generates more CO2 per unit of energy than other fossil fuels. Over 90% of the greenhouse gas emissions for coal are emitted in the combustion phase, the remainder during pretreatment.
Coal is mined in both opencast and underground mines. Associated mine gas (rich in methane, a strong greenhouse gas) is partly utilized in mining processes, but is also partly vented to the atmosphere.
Mined coal is upgraded, dried and ground in the vicinity of the mine. The upgraded coal is transported to the power station and combusted. Transportation is primarily carried out by large ships, because of the large intercontinental distances covered and the large amount of coal consumed per power station.
What remains after combustion is ashes and gypsum from flue gas desulphurization (if desulphurization is applied). These are often reused as raw materials for construction.
The greenhouse gas emission figures for coal included in the ETM concern all processes mentioned above from mining to combustion, except for emissions related to production of utilized hardware, e.g. the power plant.
Coal not only contains more carbon per unit of energy, but also contains more sulfur, nitrogen and heavy metals than other fossil fuels. Impacts of untreated flue gases on environment and human health can be severe, as illustrated by impacts of acid rain and winter smog in Europe and China. Emissions can be largely reduced, however, with efficient gas cleaning equipment. Impact of remaining emissions on air quality and the environment in general is limited at most.
Without proper precautionary measures mining coal can give severe and long-term local pollution too, caused by a process called Acid Mine Drainage (AMD). In this process a sulphuric acid solution is formed, which leaches heavy metals from the rock matrix of the mine. The resulting heavy metals containing solution destroys surface water ecosystems and pollutes soil This process may continue for centuries.
The numbers and references used to quantify the fuel chain emissions for coal can be found on our 'Reference Manager'. The Fuel Chain Emissions documentation can be downloaded from here (will open in a new tab).