Coal is one of America’s most abundant and affordable energy sources, and has served for decades as the country’s primary base load electric fuel. Coal comes with significant environmental trade-offs, including local air and water pollution, deforestation, and mountaintop removal from mining process, and greenhouse gas and toxic particulate emissions from burning it to generate electricity.

Given plentiful U.S. supplies of low-cost coal, there is clear economic and energy security rationale for continuing to use coal, and government and industry have worked for years to promote and demonstrate “clean coal” technologies. It is hoped that these technologies will capture CO2 and other emissions, thereby limiting coal’s environmental impacts, and facilitate coal’s societal benefits while reducing its societal costs.

The technology needed to make coal clean exists, but it’s expensive and struggling to achieve commercial viability. Absent a mandate, or a price on CO2 or subsidies to make “clean coal” more cost-competitive, utilities and consumers don’t face the pressures that many believe are necessary for “clean coal” to become viable on a meaningful scale.

What’s the future of coal in the U.S.? What will it take for “clean coal” to reach meaningful commercial viability?