Coal and environmental impact

The less known coal’s characteristic is for sure its environmental friendly quality, according to present laws.

That is particularly true in Italy, where 9 out of 13 coal plants have EMAS certification – the European environmental certification, more severe compared with ISO 14001. We are talking about 84% of the coal installed power (equal to about 9.500 Mw of power). These plants excel also according to efficiency, with a productivity of 40% compared with 35% of the European average and with 25% of Continental Europe.

Coal plants are even more productive with a performance of 46%. The modern coal plants in Torrevaldaliga e Vado Ligure have already reached an efficiency rate of 46% and are among the most innovative plants in Europe. The investments aimed at cutting pollution follow two lines of action: • The reduction of polluting emissions thanks to increasingly sophisticated systems for the treatment of fumes, including de-sulphurisation and de-nitrification units, plus dust extractors; • The prevention of the formation of polluting emissions at their origin through innovative techniques and processes which improve energy efficiency.

The results of these investments are a rapid and significant reduction of all polluting emissions, achieving the following goals:

  • 70% reduction in emissions of sulphur dioxide (SO2) when compared with the rate of 20 years ago. Today sulphur dioxide emissions are equivalent at 100 mg/Nm? Recent legislations have fixed maxima at 200 mg/Nm3;
  • Strong reduction in nitrogen oxides (NOx). A first important decrease of nitrogen oxides emissions was registered during the 90s and today they can be valuated at 100 mg/Nm?, a value clearly lower than the one imposed by law (the limit is fixed at 200 mg/Nm3);
  • Reduction of dusts emissions: in the 90s they were reduced of 63%, in 2003 another reduction of 75% has been registered. Today dusts amount at around 15 mg/Nm? (the total reduction is not foreseen by the law) while the limit is 30 mg/Nm3;
  • 100% recovery of ash and chalk. They can be easily reused for the production of pilling, cement, street paving and for the production of building material.

Moreover in 2000, 10 years before the Kyoto Conference established its objectives, Italian coal plants had reduced carbon anhydride (CO2) emissions of 7,6%. In consideration of Kyoto objectives the Association has ordered a study on CO2 emissions to the Experimental Station for Fuels, Milan, in order to analyse the effective CO2 emissions – during the entire life cycle.

In particular the study compares CO2 coal and gas emissions not only during the combustion, but also in the pre-combustion phases. The comparison of the whole life cycle decrease therefore the distances: the greenhouse gases total emissions would result between 510 and 670 grams of CO2 -equiv./kWh for gas (420 if the gas would be produced in Italy) and between 780 and 910 grams of CO2 -equiv./kWh for coal.

CO2 emissions in the entire life cycle

In fact, the pre-combustion data underline a higher level of CO2 emission for gas, with peaks of 288 gr of CO2 -equiv./kWh in the Russian gas case.

While, for coal, the emission recorded are equal to 127 gr of CO2-equiv./kWh in the case of extractions from underground mines and just 127 gr of CO2-equiv./kWh for mines on the surface.

Aiming at increasing the compatibility of coal with the environment and the electric production efficiency, several research initiatives have been launched in all major countries.

Among the recent most i n n o v a t i v e projects there is the one launched by ENEL, in collaboration with ENEA and ITEA to build a demo plant for CO2 capture and storage in Brindisi. The 50 megawatt plant with zero CO2 emissions, will cost 100 million Euro and will be into production from 2010.

Adding to that, the ENEL plant in Porto Tolle is planned to be converted to coal, as one of the six CSS projects which will benefit from European funding. Total funding estimated for the installation of the new CCS technology on a 660 MW coal unit is Euro 100 million. The capture system will be able to treat emissions corresponding to 250 MW of electricity generation.

In Italy ENEA, in collaboration with Ansaldo and Sotacarbo, is taking forward a study in on the gasification of coal in Sulcis Power plant with the separation of CO2 allowing hydrogen production. Also ENEL has recently launched a project on hydrogen production from coal for the future Hydrogen Park in Venice.

One of the most studied issue is the use of new methods for electric production based on the hydrogen uses starting with coal. In particular United States have launched the 1 billion dollar project “FuturGen” which aims at using integrated sequestration and hydrogen research initiative for testing new clean power, carbon capture, and coal-to-hydrogen technologies.