Dr. Conca reports that the Southern Company and Mississippi Power announced that they would be turning their clean coal power plant project into a natural gas power plant. The Kemper County Power Plant in rural Mississippi was the largest clean coal project in the U.S. Kemper embodied the hope that coal could become a major part of a future clean energy mix, coupled with low-carbon sources like renewables and nuclear.
The 582 MW power plant was designed as a gasification plant, turning the dirtiest of coal (lignite) into syngas (mostly hydrogen). The plant also has an advanced amine-based carbon capture and sequestration (CCS) system that would have captured over half of the coal carbon emissions. As an Integrated Gasification Combined Cycle (IGCC) plant, Kemper would have used a gasifier to convert locally-mined lignite coal to syngas, which would then drive a combined cycle turbine as in a normal gas plant. But Kemper had construction delays and cost overruns, spending 7 years and 7 billion dollars trying to use coal in the plant, more than twice the projected costs. The Department of Energy kicked in $382 million in grants, and in 2014, the state legislated that $800 million of Kemper costs be passed on to ratepayers. So when Mississippi Power asked regulators for permission to charge customers even more to cover new costs, the state Public Service Commission said no. Instead, the Commission ordered the facility to use only natural gas and to stop the coal gasification part of the plant, unless they wanted to finance it themselves, thus ending the clean coal aspect of Kemper. The attempt to make coal clean is difficult to engineer.
In an IGCC plant, coal is combined with oxygen and steam in the gasifier to produce the syngas, which is mainly hydrogen and carbon monoxide (CO). CO is combined with water to produce even more hydrogen and CO2. So while the technology continues to advance, the failure of Kemper shows that clean coal remains an oxymoron.
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