The percentage of electricity generated in coal-fired power plants fell to its lowest level since 1978 at the end of last year, the U.S. Energy Information Administran reports. The EIA cites warmer weather and cheaper natural gas prices (which led to expanded generation) as the primary reason that coal generation is dropping—though shuttered coal plants, an expanding renewable energy sector, and recession-inspired energy conservation are factors as well.
Here's a chart of coal's share in electricity generation in the US over the last three years:
Coal-fired power plants, as you'll recall, are the number one source of greenhouse gas emissions worldwide. They also impose a tremendous toll on public health. So it's welcome news that its share of the energy pie is diminishing, even if it is often being replaced at the moment by natural gas, a fossil fuel that emits fewer greenhouse gas emissions when burned.
But this goes beyond cheap natural gas. Coal plants are going offline in droves, thanks in party to local campaigning and pushes from environmental groups—the Sierra Club's Beyond Coal campaign has been extremely effective on this front.
Natural gas prices have dropped significantly this winter, leading the generators in some states (such as Ohio and Pennsylvania) to significantly increase the share of natural gas-fired generation. Natural gas combined-cycle units operate at higher efficiency than do older, coal-fired units, which increases the competitiveness of natural gas relative to coal.
And though its share is still comparatively tiny (in the graph above it's callously herded into the 'other' category), renewable energy like solar and wind continue a rapid expansion. In other words, the trends are pointing in the right direction, generally speaking. Less coal, more renewables. Now we just have to amplify both trajectories exponentially.