Clean and safe carbon-based energy enables Europe to safeguard security of supply and diversity of fuel sources,
whilst meeting the need for deep cuts in emissions of CO2 and other pollutants. The EU is already finding it increasingly difficult
to comply with international commitments with regards to environmental protection. In the Kyoto Protocol, for example, the EU agreed
to an 8% reduction in CO2 and other greenhouse gas emissions by 2008-2012, compared with 1990 levels. However, it is now expected that
CO2 emissions in 2010 will in fact be about 7 % higher than in 1990, if no major new policies are introduced. In Greece and since 1990,
CO2 emissions have increased systematically, resulting in an increase of approximately 16.7% in 1999 compared to 1990 levels.
Combustion of fossil fuel accounts for 91% of total CO2 emissions, while the remaining 9% result from cement and lime production.
Research into CO2 mitigation and the production of clean fuels, particularly hydrogen, is essential to support the drive to reduce
decrease pollution and greenhouse emissions. In the last 20 years great progress has been made in the separation of gases by membrane
technology. Although still at an early stage, this technology has been successfully tested in various industrial processes e.g.
air separation, hydrogen recycling and natural gas purification. Membranes offer several advantages such as small size, simplicity of
operation and maintenance, compatibility and diversity. The application of polymer membranes for the recovery of CO2 from flue gases of a
power plant showed that considerable CO2 removal (up to 90%) could be achieved, and the economical competitiveness of the process depends on
the selectivity of the polymer materials. Apart membrane technology, various CO2 capture technologies have been examined, showing that
present state of the art polymer membranes are less expensive and energy demanding than MEA-absorption, cryogenics and TSA processes.
On the other hand, they are less competitive to selexol-absorption and PSA, especially in terms of final CO2 purity. However, membrane
technology has significant environmental benefits, since its application does not result in pollutant by-products, such as spent
solutions and solids, requiring further treatment and disposal. From the results obtained, it is evident that CO2 removal in coal
upgrading processes is technically feasible. Significant amounts of CO2 emitted from future power stations in the atmosphere can be captured
and mitigated, especially with the use of presently available, state of the art polymer membranes. However, the energy penalty is substantial
(about 8 to 14 percent units of total output), and its reduction should be further examined in terms of more sophisticated steam cycles
and gas turbine designs. Significant improvements in energy efficiency and CO2 mitigation can be achieved with the use of multistage
operation at elevated pressure. Additional improvements can be realized by development of advanced materials for polymer and ceramic
membranes, which could further improve the competitiveness of membrane technologies. In terms of CO2 sequestration, and through specific
European projects, four of the most promising types of geological storage are being studied in various areas of Europe including Greece.
These storage types include
(a) Onshore/offshore saline aquifers with or without lateral seal,
(b) Low enthalpy geothermal reservoirs,
(c) Deep methane-bearing coal beds, and abandoned coal and salt mines and
(d) Exhausted or near exhausted hydrocarbon structures.