Despite all of the attention given to wind and solar power, the development and deployment of advanced coal technologies may be far more important in shaping our energy future. Consider where world energy use and research is headed. Coal, and other fossil fuels, remain the backbone of the global energy system and will remain so for the foreseeable future.
If the politics of coal have never seemed so anguished, the economic prospects of advanced coal technologies with higher generating efficiencies have never seemed so promising. Not so far into the future, several new coal technologies are expected to come into greater commercial use in the United States. The best known are new pulverized coal combustion systems, operating at increasingly higher temperatures and pressures, and plants with an integrated gasification combined cycle. Increasing the average efficiency rate of the U.S. coal fleet from 33 to 40 percent using these available technologies would reduce coal-plant emissions by between 14 and 21 percent.
And there may yet be cost-cutting breakthroughs in the development of techniques to capture carbon emissions from power plants – both coal and natural gas units — and use the carbon to produce petrochemicals, plastics and other useful products. Researchers at the Massachusetts Institute of Technology and other leading universities are trying to come up with the answers.
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Global warming will continue unless all countries reduce carbon emissions. That’s because most countries burn coal, which is responsible for about 45 percent of the world’s carbon emissions. The U.S. Energy Information Administration projects that even as coal’s share of U.S. electricity generating capacity declines, its world use will rise from about 30 percent today to 50 percent by 2035.
Its environmental impact notwithstanding, coal is a practical energy option for fast-growing economies like China and India, which don’t have large natural gas resources. These countries are determined to grow their economies and lift millions of people out of poverty, and do it at the least cost possible.
Given the certainty that coal will continue to play a large and indispensable role in electricity production, the way forward requires the deployment of innovative coal technologies to mitigate carbon emissions.
The World Coal Association says that lifting the average global efficiency rate of coal plants to 40 percent compared to 33 percent today would reduce carbon output by an amount equal to India’s annual carbon emissions, which are among the highest in the world. Some coal plants operating with ultra-supercritical technology in Europe and Japan are already achieving efficiencies in the 42 to 46 percent range.
Importantly, higher efficiencies are a critical step toward the use of carbon capture, use and storage technology, without which, it is highly improbable that global carbon emissions can be brought down to acceptable levels.
Despite the challenges, several projects have been launched to develop and test processes for capturing and sequestering carbon. Most of this activity is under way in the United States, and its cost is being shared by government and private industry. For example, NRG Energy is pumping carbon dioxide 80 miles by pipeline from its coal-burning Parish power plant in Texas and using it to extract more oil and natural gas from old wells.
Exxon Mobil is a major partner in a carbon mitigation project that uses fuel cells – devices that generate electricity through chemical reactions. The idea is to connect fuel cells to fossil-fuel plants, so that the fuel cells can generate additional power to make up for the cost of sequestering the carbon.
In Alberta, Canada, a company is injecting carbon captured from a natural gas plant and injecting it into concrete. The process reduces the need for composite material when making concrete and makes it stronger. So far it’s been put into use at about 50 concrete plants over the past two years.
And in Mississippi, a Southern Company power plant that burns lignite coal strips out about 65 percent of the carbon from gas emissions, then pumps it to other companies for use in enhanced oil recovery.
The basic attraction of coal remains its low cost and abundance. In the next 10 to 20 years, coal’s value is likely to grow, as advanced coal plants, including some retrofitted with carbon capture, meet the world’s growing need for energy while helping reduce greenhouse emissions.
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