Sunday, April 19, 2009

More on the U. of Witswatersrand Breakthrough for Getting More Energy from Coal

"The whole combustion process is very inefficient and when electrical engineers and mechanical engineers talk about inefficiency they are talking about efficiency of the power plant, but actually there are much more inefficiencies in the chemical side of the combustion, which hasn't been looked at properly yet," Glassser indicates.

"Taking coal, and turning it into electricity in a power station is incredibly inefficient. There is a large amount of chemical potential energy in coal, which you lose by burning, and so we are looking at ways of trying to improve that," he adds. _Source
Most journalistic coverage of the development from Witswatersrand has focused upon the lower CO2 emissions involved -- since they are using CO2 plus H2 from a modified gasifier to produce liquid fuels via a modified F-T synthesis. That process removes the CO2 as part of the synthesis. I haven't read the original article in Science yet, so I cannot comment more on the total energy balances involved.
"Our research has enabled us to develop new techniques for analysing how processes work and what causes emissions, and methods to design processes with reduced carbon dioxide emissions. Having understood these, it is relatively simple to eliminate unnecessary emissions and minimise the contributions from other sources," explains Prof. David Glasser, one of the scientists from Wits involved in the research.

He tells Engineering News that, traditionally, chemical engineers have looked at mass and energy to design plants - "we have added a third concept of ‘work' - and ‘work' is essentially the potential energy of the system and how you use it".

He further explains that similar to when you have a big heavy ball at the top of the hill, you can either kick it down and let it run to the bottom, and get no work from it, or alternatively, you could use it to drive a motor as it falls, in which case you get work from the object.

The research has added work to the analysis. "And using that, you suddenly get powerful methods of stating what the potential is for a chemical plant. If you haven't used that potential, you may have lost it forever. In which case, you have got an inefficient plant and the end result of that is that you emit more carbon dioxide".

In an article published in the international journal Science, co-authored by Glasser, Prof. Diane Hildebrandt, Dr Brendon Hausberger and Bilal Patel from the Centre of Material and Process Synthesis at Wits University, and Benjamin Glasser from Rutgers University in the US, an example of the technique highlights process changes that reduce emissions. _engineeringnews
Coal, nuclear, geothermal, solar thermal, space based solar, and biomass / bioenergy. All will be needed to tide us over until we can develop limitless and cheap energy from fusion and other currently unknown physical processes. The more efficient the better, and the cleaner the better. Economics has the final say.

As mentioned previously, Brian Westenhaus has more.



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