CLEAN EFFICIENT COAL-BASED POWER TECHNOLOGY; SOME TECHNICAL ASPECTS PRIOR TO ITS REALIZATION

Supplies of oil and natural gas are decreasing quickly. However, the renewable energy sector seems not to grow quickly enough to assure the present energy consumption rate. Coal is considered a very dirty fuel, but its reserves are quite abundant. Coal reserves are finite, but clean efficient coalbased energy technology can give more time for transformation into post-fossil fuel world.
The paper discusses a very ambitious idea of such a technology, which was proposed a few years ago by ZECA Corporation [1]. However, after some time of development the project has effectively stopped [19].
In this project the concept of coal power plant is totally changed. Instead of being combusted, coal is gasified, then hydrogen is produced, which feeds stacks of solid oxide fuel cells (SOFC). Cyclic CaO/CaCO₃ reaction is employed to enhance hydrogen production and to separate carbon dioxide. Virtually no pollution is emitted. All carbon dioxide is produced as clean, concentrated and easy for sequestration stream. SOFC by-product - heat is carefully recycled and improves overall efficiency of the process, which can reach about 60%.
The paper discusses various technical requirements, which must be met, before the project comes to life.
These technical issues are mainly connected with requirements for SOFC (very high operating temperature, high sulphur tolerance, integrated heat exchanger) and CaO/CaCO₃ process (performance decreases with the number of cycles and difficulties arise with heat transport into calcination vessel). Although technical difficulties are discussed on basis of ZECA Corporation project, the issues have rather universal character and is very likely that identical or similar problems will appear in other concepts of clean efficient coal technology.