EN08 Emissions (CO2, SO2 and NOx) intensity of public conventional thermal power (electricity and heat) production
Assessment made on 01 Apr 2007
ClassificationEnergy (Primary theme)
DPSIR: Driving force
- ENER 008
Policy issue: Is the use and production of energy having a decreasing impact on the environment?
The emissions intensity of carbon dioxide (CO2), sulphur dioxide (SO2) and nitrogen oxides (NOx) from public conventional thermal power plants has decreased substantially since 1990, particularly in the case of SO2 and NOx. This is primarily due to a decline in the use of coal, and replacement of old, inefficient coal plant as well as the use of abatement techniques. However, in recent years a rise in the coal-fired electricity production has acted to slow the decline in emissions intensity. Rising overall electricity consumption has also acted to partly offset the environmental benefits from improvements in emissions intensity. While CO2 intensity has decreased, CO2 emissions have increased in real terms by around 8% between 1999-2004.
Electricity and heat production from public thermal power plants is a significant source of both air pollutants and greenhouse gas emissions. Reducing the emissions per unit of electricity and heat produced (emissions intensity) of these plants can play an important role in helping to reduce their environmental impacts.
Emissions of carbon dioxide (CO2), sulphur dioxide (SO2) and nitrogen oxides (NOx) per unit of electricity and heat produced by public conventional thermal power plants (i.e. the emissions intensity) decreased substantially during the period 1990-2004, with the majority of the reduction achieved during the 1990s and improvements slowing down from the late 1990s onwards. The reductions in SO2 and NOx emissions intensity have been particularly significant, influenced by emission abatement techniques such as flue gas desulphurisation and low-NOX burners, and the greater use of low-sulphur fuels (see EN09 for the quantitative contribution of each factor to reduced emissions). Emission reductions have also been helped by some switch in electricity production from coal and oil to natural gas, prompted by the liberalisation of energy markets and improvements in the efficiency of electricity production. However, action is still required to ensure further reductions, particularly in the new Member States, as on average the emissions intensities of all pollutants, and in particular SO2, in these countries are still higher than the average for the older Member States.
The intensity of carbon dioxide emissions from public conventional thermal power plants in the EU-25 decreased by about 28 % from 1990 to 2004 due to improvements in all Member States with the exceptions of Estonia and Slovakia. This reduction has generally occurred as a result of the closure of old and inefficient coal-fired plants and their replacement with either newer, more efficient coal-fired plants or new gas-fired plants. The latter was primarily driven by economic decisions, as over this period the costs of electricity produced from gas-fired plants have typically been less than for coal- and oil-fired plants, leading to a preference for new gas plants. However, increased gas prices towards the end of the period have led to higher utilisation of existing coal plants in some EU countries and, as a result, the CO2 emissions intensity has changed relatively little since 2001. Typically natural gas has approximately 40 % less carbon content than coal, and 25 % less carbon content than oil. Combined cycle gas turbine (CCGT) technology, the technology most often used with new gas power plants, can achieve at least 55-60 % efficiency compared with the 35-40 % efficiency of traditional coal-fired power plant, and thus further reduce the emissions intensity. Latvia and Sweden achieved the largest percentage reduction in the intensity of carbon dioxide emissions in the EU-25, with an average annual decrease of 7% and 5.3% respectively. In Latvia this was largely due to greater use of gas at the expense of coal, lignite and oil for electricity production. Sweden had the lowest CO2 emissions intensity in 2004, which was mainly due to a negligible share of coal and lignite in power production and a high share of renewable energies (see EN27). With the exception of France, which produces very little public conventional thermal power, Estonia and Greece have the highest carbon intensity of all Member States. This is due to the continuing dominance of coal and lignite (92.5% in Estonia and 59.6% in Greece) as well as a high share of oil in Greece (14.1%) as a fuel for public conventional thermal power production (see EN-27 for further details on fuel use by countries).
During the period 1990-2004, the emissions intensity of nitrogen oxides from public conventional thermal plants decreased by 60%. This was due to the increased use of end-of-pipe abatement techniques such selective catalytic reduction, low-NOx burners and the use of less polluting fuels in public conventional thermal power production in many Member States. Low-NOx burners reduce emissions by controlling the mixing and proportions of fuel and air in the combustion process and typically can reduce NOx emissions by up to 40 %. Selective catalytic reduction uses a chemical reaction involving ammonia to convert NOx to nitrogen and water and removals of up to 90 % can be achieved. NOx intensities fell in all Member States (except Estonia), with the largest decreases occurring in Italy and the Czech Republic. While this reduction was mainly due to large increases in the use of gas for electricity production in Italy, in the Czech Republic a combination of constructing new fluidised bed boilers and implementing NOx control technologies on existing boilers has significantly reduced NOx emissions. The country with the highest NOx intensity is France, although it produces relatively small amounts of public conventional thermal power, mostly from coal and oil.
The emissions intensity of sulphur dioxide from public conventional thermal power plants decreased by almost 80% from 1990 to 2004, a significantly larger reduction than occurred for either CO2 or NOX emissions intensities from public conventional thermal power plants. In particular, Germany, Denmark, Latvia and the Czech Republic showed large reductions in emissions intensity. In Denmark this occurred through a twelve-fold increase in the use of natural gas, while in Latvia there was a substantial decrease in the use of coal, lignite and oil. In Germany the SO2 reductions have been due mainly to the closure of old, inefficient lignite-based power plants following reunification, but also due to the extensive use of flue gas desulphurisation technologies. Flue gas desulphurisation is an abatement end-of-pipe technology, which is fitted to large combustion plants such as power plants. The application of this technology has been driven by national efforts to reduce SO2 emissions and also in response to the implementation of EU Directive 88/609/EEC (superseded by Directive 2001/80/EC) on the limitation of emissions of certain atmospheric pollutants into the air from large combustion plants. Cyprus, Greece and Spain had the highest SO2 emissions intensities in the EU-25 in 2004, influenced by the use of high sulphur content coal and lignite in the two former countries and high sulphur oil in Cyprus.
According to the most recent PRIMES energy projections (European Commission 2006), the CO2 emissions intensity of public conventional thermal power production in the EU-25 is expected to continue to decline, at an average annual rate of 1.4 % over the period 2000-2010. After 2010, the CO2 intensity is expected to continue declining at a faster rate (1.9%) until 2020. New policy initiatives and the widespread implementation of competition in the energy markets are predicted to encourage further switching to low-carbon fossil fuels (mainly natural gas) and improve the efficiency of public conventional thermal power production.
In the longer term, the prospects for continuing this trend look less certain. PRIMES energy projections suggest a slower rate of decline in CO2 emissions intensity over the period 2020-2030 (0.4%). Under a low carbon energy pathway (EEA 2005), a greater reduction in emissions intensity, continuing to 2030, would be expected as the energy system responds to rising carbon permit prices. The decline in CO2 emissions intensity is predicted to be greater in the new Member States (2.1% 2010-2020 and 1.3% 2020-2030).