Hybrid system could cut coal-plant emissions by half

MIT scientists have proposed a new concept that could make it possible to generate electricity from coal with much greater efficiency - possibly reaching as much as twice the fuel-to-electricity efficiency of today's conventional coal plants.
This would mean a 50 per cent reduction in carbon dioxide emissions for a given amount of power produced, researchers said.
The key is combining into a single system two well-known technologies - coal gasification and fuel cells, they said.
Coal gasification is a way of extracting burnable gaseous fuel from pulverised coal, rather than burning the coal itself. The technique is widely used in chemical processing plants as a way of producing hydrogen gas, researchers said.

Fuel cells produce electricity from a gaseous fuel by passing it through a battery-like system where the fuel reacts electrochemically with oxygen from the air, they said.
The attraction of combining these two systems is that both processes operate at similarly high temperatures of 800 degrees Celsius or more.

Combining them in a single plant would thus allow the two components to exchange heat with minimal energy losses, researchers said.
The fuel cell would generate enough heat to sustain the gasification part of the process, eliminating the need for a separate heating system, which is usually provided by burning a portion of the coal, they said.

"Coal gasification, by itself, works at a lower temperature than combustion and is more efficient than burning," said Katherine Ong from Massachusetts Institute of Technology (MIT).
First, the coal is pulverised to a powder, which is then heated in a flow of hot steam, somewhat like popcorn kernels heated in an air-popper.
The heat leads to chemical reactions that release gases from the coal particles - mainly carbon monoxide and hydrogen, both of which can produce electricity in a solid oxide fuel cell.
In the combined system, these gases would then be piped from the gasifier to a separate fuel cell stack, or ultimately, the fuel cell system could be installed in the same chamber as the gasifier so that the hot gas flows straight into the cell.

In the fuel cell, a membrane separates the carbon monoxide and hydrogen from the oxygen, promoting an electrochemical reaction that generates electricity without burning the fuel.
Because there is no burning involved, the system produces less ash and other air pollutants than would be generated by combustion.
It does produce carbon dioxide, but this is in a pure, uncontaminated stream and not mixed with air as in a conventional coal-burning plant.
The Chief Minister said he would like to request the
Prime Minister again to share 60 per cent of the the Cess with the states through an appropriate sharing mechanism.

He said the coal royalty should be appropriately increased commensurate to the cess to ensure sharing of benefits of coal mining with the states in a fair manner.
"The Central government has also collected additional levy at the rate of Rs 295 per ton from the prior allocates of Scheduled-II coal mines which should be transferred to the state government," Patnaik said.
Patnaik also pointed out that the contribution of DMF for coal has been made payble only from October 20, 2015 and not from January 12, 2015 as in case of non-coal minerals.
"This has further deprived the coal bearing states from realising the full benefits of DMF contribution allowed by the MMDR Amendment Act, 2015 enforced with effect from January 12, 2015. This anomoly needs to be rectified in the interest of the persons affected by coal mining," Patnaik said.