Environment

Hybrid system could clean up coal power

Hybrid system could clean up c...
An artist's rendering of a possible hybrid system showing steam (pink arrows) passing through pulverized coal, and releasing gas which goes through a fuel cell at the top to create electricity
An artist's rendering of a possible hybrid system showing steam (pink arrows) passing through pulverized coal, and releasing gas which goes through a fuel cell at the top to create electricity
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An artist's rendering of a possible hybrid system showing steam (pink arrows) passing through pulverized coal, and releasing gas which goes through a fuel cell at the top to create electricity
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An artist's rendering of a possible hybrid system showing steam (pink arrows) passing through pulverized coal, and releasing gas which goes through a fuel cell at the top to create electricity

Even though 2015 saw the biggest decline in coal usage around the world on record according to Greenpeace, the use of the material is still thriving globally. In fact, according to the US Energy Information Administration, global coal consumption was at about eight billion short tons in 2012 (around 7.2 billion tonnes), the most recent year for which the agency provides statistics. So if coal isn't going away any time soon, what is there to do about the fuel source that is often blamed for pollution and global warming due to carbon emissions? Make it more efficient. And that's exactly what a new hybrid energy system out of MIT could do.

According to MIT News, conventional coal-burning power plants only convert 30 percent of the energy contained in coal to electricity. That's a pretty low efficiency rate. A new system that combines two existing technologies — coal gasification and fuel cells — could up that rate to between 55 and 60 percent, in effect halving the amount of carbon dioxide produced for producing the same amount of energy using today's methods.

Both of these methods are currently used to create energy in today's world, but stacking them together in one system could be the key to greater efficiency, says MIT doctoral student Katherine Ong and professor Ahmed Ghoniem, who reported their theory in the Journal of Power Sources.

The system would start with coal gassification, a process where coal is crushed to a powder and heated in a flow of hot steam that releases the gases it contains — primarily carbon monoxide and hydrogen.

After those gases are freed, Ong and Ghoniem suggest funneling them through a fuel cell where a membrane splits off the carbon monoxide and hydrogen from oxygen, thus creating electricity. Such fuel cells were announced in 2011 by a team from Geogia Tech. The fuel cell would, in turn, create heat that could generate more steam to continue the gasification process. This would eliminate the need to burn some of the coal to generate the higher temps at which gasification occur.

Because nothing is actually burned in this system, the researchers say that there would be less ash and other pollutants from a plant employing this method which, thus far, has only been tested using computer simulations. And while carbon dioxide would be a byproduct of the process, it wouldn't be mixed with air, as is the case in traditional factories, which would make it easier to capture and sequester.

To test out the real-world application of the hybrid theory, Ong says a small pilot plant should be built which, she adds, could happen relatively quickly. "This system requires no new technologies," she says. "It's just a matter of coupling these existing technologies together well."

Late last year a process that uses algae and the coal dust usually wasted from mining operations to produce burnable bricks was created by researchers at the Nelson Mandela Metropolitan University (NMMU) in South Africa. That process, along with with MIT's hybrid system, could certainly help coal shake off its reputation as a dirty fuel source and help the world get more efficient power from the material for years to come.

Source: MIT News

9 comments
Snerdguy
It's still dirty even at twice the efficiency. So, it's not a realistic option. If they come up with a process that can use coal without ANY regrettable pollutants like with wind or solar, we'll talk. Even carbon dioxide is a pollutant unless it can be permanently sequestered.
VoiceofReason
As usual, only reading part of the story. There are countries, China amongst them, who will use coal regardless of how dirty is it. This will up the efficiency and reduce what goes into the air because they will burn less of it.
StWils
VoiceofR is correct but not quite complete. There are several processes that use CO2 as a feedstock to produce hydrogen or various liquid fuels that can directly replace diesel, gasoline or be used to build other chemicals. Also, there is still a significant amount of heat left over that could be captured and transported modest distances and used as "process heat" in lots of industrial processes. It sounds attractive and imaginative to envision a totally contained linear system but it is safer and far more stable to be able to capture and control the CO2 so that it can be used as needed by nearby industrial consumers. The objective would be to have a more robust durable array of companies using the coal, it's component gases, and finally the "waste" heat itself. The net system efficiency could be a lot more attractive and still lessen the total amount of coal used. Achievable even if not getting to the point of leaving all the coal in the ground.
zevulon
improving coal is the best possible investment of energy expenditures for a future with electrified cars, electric bussess and non petroleum fueled internal combustion transportation. it is amazing how much green ideology/religion creates a faith in the god of 'renewables' and casts coal as evil satan. instead of using their rational brains that god gave them, the green faithful simply follow the prayers set out of them. why is this? let us examine the obvious. the future of a green world is one where the entire electricity grid is used to transport our energy , rather than pipelines and tubes and fuel carrying rail and truck. why? because 1)electricity is efficient to move compared to fuel itself. 2) any revolution in energy STORAGE must utilitze the grid to be efficient at transporting energy from where it is created to where it is stored and to where it is consumed. the complex benefits realized from 'grid batteries' located at production facilities or on your roof, can only be realized through a better funcitoning electricity grid. THEREFOR. improving the 'low hanging fruit' of the dirtiest energy on the grid will make the GRID itself far more efficient at transporting what is now green electricity. natural gas is burned so cleanly and efficiently in turbines that it cannot be improved much. solar and wind are great but they are not the be all and end all. they are both relatively clean already and , more importantly , marginal improvements in them don't make a huge difference as they both still only account for a small % of grid electricity produciton. COAL is super dirty. cleaning up coal and making it more efficient would yield in tremendous gains as it already accounts for 30+% of electricity. with a more effecitve grid that produces MORE AND CHEAPER ELECTRICITY electric cars and grid powered transportation becomes more attractive to the already dominant petroleum fueled supply network to the transportation network of internal combustion engines on the road. and petroleum is already very cheap. so without increases in aggregate of electricity production , electricity cannot compete with petroleum. a green future relies on cleaner coal. Anyone who would rather sabotage the grid by eliminating coal simply wants to increase electricity prices which guarantee the dominance of petroleum for transportation . which diminishes demand for electricity, which DETRACTING from the possiblity of getting off petroleum in the next 100 years. therefore the grid is our salvation as a means of t
antiguajohn98
Clean coal is a dirty lie!
Stephen N Russell
Test in coal fired plants alone & examine results, then upgrade plants. More can be done for coal plants & have China pay huge lisc to use system
Bruce Miller
Finally! From America! a Breakthrough in Logic! Yes! The 19th century "waste flow" is in reality a 21st century 'Resource Flow"! Nature has done this forever. We did not see it at first. So happy to see American science and technology taking this route! NOW: find good use for all flows from any process and we will not only become environmentally compatible we will become so efficient, few can compete - especially the open hearth coal fires of China. SMART! Use your head, not your back! and move the American Empire into the 21st century and beyond. Drop all old prejudices, rise above the 'pat answer' folk, bypass the 'sunk money' Senators, and reach for a better life for all humanity!
Don Duncan
It has been found that the regulation/subsidy of the energy sector is the biggest impediment to advancement. All problems are solved faster, better, cheaper by the private sector, despite govt. propaganda to the contrary. When the govt. gets it wrong, we all suffer, but there is no accountability because it is assumed good intentions are more important than greedy market forces. The desire to profit from providing answers to problems is no vice. It provides the world with all its goods/services. Govt. consumes wealth, transfers it to non-productive, many times destructive uses, on net. The larger the private sector, the higher the standard of living is seen, e.g., more authoritarian societies are less productive. It took the USSR 74 years to collapse because of their strong faith in the force of govt. Now they practice a mixed version of communism, fascism, and capitalism, like every other nation, and are better off. The first nation to stop the fascism/communism (socialism) all together and go to pure capitalism will be anti-authoritarian as expressed by an all voluntary socio-economic system. No initiation of force will be tolerated.
Calson
Money would be better used to build wind farms and install solar panels on people's homes and on business rooftops. Problem with coal is not only the toxic emissions and increase in release of carbon. Coal also needs to be mined and transported to the power plant and then the energy produced needs to be transported to users. Much more efficient, obviously, to have production near the point of consumption and to use the existing transmission grid. Important to appreciate that coal plants are not efficient uses of capital as you need capacity to meet peak demand even if that demand exists only for a few months during the year or a few hours on a summer day. Same lack of economic efficiency with nuclear power plants which is why every single one requires a $8 billion dollar subsidy by the taxpayers and utility customers. Solar panels when used with smart string inverters can smooth out fluctuations in the power running over the grid and greatly reduce the odds of a rippling brownout that cascades into a regional or even national blackout. Single large production sources only make the grid more vulnerable to failures of this type.