Coal: a clean energy source for the future?

Coal is making a comeback as a cheap and reliable source of energy. With global energy demand rising at an unprecedented rate, the world's vast coal reserves are attracting growing interest from governments in Europe, the US and Asia. But while the efficiency and cleanliness of coal-fired power stations is improving, coal remains the dirtiest of all fossil fuels. Genuinely clean coal – i.e.: one that emits close to zero CO2 thanks to carbon capture and storage technology – is not expected to become economically viable before twenty years. And with the growing sense of emergency surrounding global warming, coal is simply not the answer, environmentalists argue.

Rising oil and gas prices, combined with geopolitical instability in major producing regions, is putting coal firmly back on the agenda as a reliable and cheap source of energy. Global coal demand is expected to grow steadily over the next decades, with most of the demand coming from China and India but also from the United States (IEA energy outlook). Coal has several benefits:

  • World reserves  are huge and believed sufficient to last for 180 years at current consumption levels, according to the International Energy agency (IEA). A March 2007 report  by independent German scientists (the Energy Watch Group), on the other hand, comes to different conclusions. Criticising the quality of coal reserve statistics, these experts estimate that global coal production will peak around 2025 at 30% above present production.
  • Deposits are relatively evenly distributed around the globe, the United States (27%), Russia (17%), China (13%), and India (10%) holding the bulk of reserves. By comparison, European OECD countries hold about 0.45% of reserves (source: IEA);
  • Coal can be stored and used rapidly as a back up to other energy sources (e.g.: wind) in case of a demand peak.

In the EU, the situation varies greatly from one country to the other:

  • Consumption: Germany is Europe's single largest consumer of coal with 82 million tonnes of oil equivalent (Mtoe) consumed in 2005. It is followed by Poland (57 Mtoe), the UK (39 Mtoe), Spain (21 Mtoe), the Cezch Republic (20.5 Mtoe), Italy (17 Mtoe) and France (13 Mtoe) (source: BP statistical review of world energy 2006);
  • Production: Poland is the EU's largest coal producer (69 Mtoe) and the world's 7th largest. It is followed by Germany (53 Mtoe), the Czech Republic (23.5 Mtoe) and the UK (12.5 Mtoe) (source: BP statistical review of world energy 2006);
  • Share of coal in power generation: Poland relied on coal for 92% of its electricity generation in 2002. The Czech Republic (65%) and Greece (62%) also rely heavily on coal for electricity generation. Germany stood at 50% (source: Commission). In France, coal was largely abandoned in favour of nuclear for power generation.
  • Air pollution and waste

Emissions of pollutants (mainly Mercury - Hg; Nitrogen Oxides - NOx; and Sulphur Dioxide - SOx) are the main environmental problems associated with the use of coal. SOx emissions in particular pose the most significant challenge as they cause acid rain.

However, a range of advanced combustion techniques already exist to reduce harmful emissions. They require less coal to run the steam turbines that generate electricity, producing fewer emissions and waste along the way. Existing technologies include:

  • Integrated Gasification and Combined Cycle (IGCC) where coal is reacted with oxygen and steam to attain a gaseous form. IGCC is said to offer up to 50% increased efficiency when burnt for electricity generation. The process is also referred to as Coal-to-Liquids (CtL) when used as a fuel directly into a car running on a special engine (Fischer-Tropsch process). The process can also be used to fuel hydrogen-powered vehicles in a future hydrogen-based economy.
  • So-called super-critical boilers which operate at high temperature and pressure to generate up to 50% more efficiency than conventional coal-fired power plants. The technology is convenient because it can be 'retro-fitted' to existing old power stations. It is also more versatile as it allows to burn biomass as well as coal as a primary fuel. More than 400 supercritical plants are in operation worldwide and China is now installing supercritical plant as standard, says the World Coal Institute (WCI).

Others are currently being developed:

  • Fluidised Bed Combustion (FBC), which can run on almost any combustible material and reduces NOx and SOx emissions by 90%
  • Pressurised Pulverised Coal Combustion (PPCC), an advanced technology developed mainly in Germany.

These processes usually involve 'cleaning up' the coal to remove minerals and other undesirable material from it, and crushing it so that it is burnt efficiently. According to the WCI, Coal cleaning can reduce the ash content of coal by over 50%, leading to much lower particulate emissions, reducing SOx emissions and improved efficiency, which in turn leads to lower CO2 emissions. However, the process also generates additional costs.

  • Reducing CO2 emissions

Despite improved combustion technology, coal is still a big CO2 polluter, way ahead of gas, and its increased use threatens to hamper global efforts to curb greenhouse gas emissions. In the long run, CO2 capture and storage deep underground in geological formations is the only technology foreseen to achieve near-zero CO2 emissions from coal. The technology can also be used to inject CO2 in depleted oil fields to enhance recovery.

However, carbon capture and storage is still under development and is currently only being tested on small scale projects and demonstration plants. Its price is currently too high to be commercially viable.

The EU Commission believes that coal-fuelled power plants will remain "the workhorse of electricity generation worldwide" for some time to come. In a May 2006 speech, Energy Commissioner Andris Piebalgs said technological developments meant the outlook for coal was "more positive today than it has been for many years". However, he added that coal use must be accompanied by reduced CO2 emissions. "We would like to challenge researchers, industrialists and Member States to demonstrate how coal can contribute to sustainable, secure and competitive energy for Europe," Piebalgs said. The Commission is funding research into clean coal technologies and carbon capture and storage under the EU's seventh research framework programme (FP7). The aim is to bring down the cost of CCS technology to less than €20 per tonne, with capture rates above 90%.

According to Dr. Heinz Scholtholt, board member of STEAG, a German energy utility, coal will remain an important energy source because of its affordable price and availability. "From a technological and ecological point of view, natural gas is far more interesting than coal, but it is also way more expensive and has to be imported, while coal is a domestic energy resource," says Scholtholt. At the same time, he acknowledges that the problem of CO2 emissions still needs to be solved. According to Scholtholt, development of near-zero emission coal-fired power plants should secure Germany's global leading position in clean coal technology.

In the UK, a Clean Coal Task Group bringing together experts from different backgrounds handed a report to Tony Blair in June 2006. The group supports the development of clean coal technologies both from an industrial policy perspective and for environmental reasons. It said "the Government's ambition should be to maintain at least the current coal-fired generation capacity in the UK (29 GW) whilst at the same time moving the whole coal fleet to clean coal technology and, ultimately, zero emissions". It said this ambition could be met by a combination of new build and retrofits and the gradual fitting of a number of plants with carbon capture and storage.

Major cuts in CO2 emissions from coal-fired power stations are not to be expected in the short run, says Christian Egenhofer, a climate and energy researcher at the Centre for European Policy Studies (CEPS) in Brussels. According to Egenhofer, current 'clean coal' technology is unable to deliver the 50 to 80% CO2 cuts that are to be aimed for by year 2050 to tackle global warming. The newest types of coal installations "may be very efficient but they are still very high in carbon intensity," he says.

However, in the long run, Egenhofer says CO2 capture and storage may just do the trick. But this technology is unlikely to become commercially competitive before twenty years time, he says. In order to make up for this, Egenhofer predicts that specific policy measures will be adopted to support carbon capture and storage in the same way that they have been applied for renewables.

WWF, the global conservation organisation, says coal power is the most carbon-rich of all fossil fuels, and therefore, the dirtiest. And according to the conservation organisation, the power sector alone is responsible for 37% of all man-made CO2 emissions. In Europe, the WWF published a study ranking power plants according to how much CO2 they produced. Twenty seven out of the 30 most polluting were coal-fired. "To switch off global warming we have to replace them with cleaner alternatives, such as gas and renewables," said WWF's Imogen Zethoven.

Two recent studies, one from March 2007 by the Energy Watch Group and another from February 2007 by the Commission's Joint Research Centre, confirm that whilst coal will remain an important source of energy in the 21st century, known reserves may be depleted more rapidly than originally expected, and extraction and production will likely become more expensive.

  • 10 January 2007: Commission presents 'energy and climate change package'  including a strategic energy review with proposals aiming towards a low CO2 fossil fuel future with support for 'clean coal' technology.

Subscribe to our newsletters

Subscribe