The volume of U.S. electricity generated by renewable energy surpassed the level sourced from coal for the first time last month and the trend is expected to continue in May, according to Department of Energy data.
A study by the Institute for Energy Economics and Financial Analysis (IEEFA), which examined figures from the U.S. Department of Energy’s Energy Information Administration (EIA), renewable energy sources including hydroelectricity are set to generate more power than coal for the first time.
The analysis predicted renewable sources to generate 2.32 TWh for April and will produce a further 2.27 TWh in May. Both figures are ahead of the 2 TWh and 2.24 TWh, respectively, expected to come from coal.
There are two trends behind the crossover and they operate on different timescales. First, as illustrated in the chart above, renewable energy generation always rises in spring, due to a rise in hydroelectric power as rivers swell, including from snow melt.
IEEFA notes spring is when many coal plants close for maintenance for that reason, as power prices are at their lowest and they are least likely to be needed.
The longer-term trend is that coal’s share of the U.S. electricity mix is falling, and that fall has been particularly precipitous over the last five years. According to the EIA, coal made up 39% of U.S. electricity generation as recently as 2014, but only 27% last year.
The main driver has been abundant, cheap natural gas due to the rise of hydraulic fracturing – fracking. More electricity has been generated from gas-fired power plants than coal on an annual basis every year since 2015.
However, wind and solar capacity is also expanding rapidly, enabling renewables to claim an increasing share of electricity generation. Wind and solar made up 9% of U.S. electricity generation last year, up from only 1.6% in 2008.
With no new coal plants being built and gas, wind and solar dominating new electricity generation, there is no end in sight for the decline of coal. In fact the question has not become whether these sources will replace coal but how much gas-fired capacity will be built before gas is eclipsed by renewables, as is already happening in California.
On the national scale, the ageing coal fleet continues to retire. The EIA predicts 7 GW of coal plant capacity will go offline by the end of next year and analysis by Energy Innovation has shown that in 74% of cases it is cheaper to build new wind and solar facilities than to keep running coal assets. That percentage is expected to rise to 86% by 2025.
It will still take a few years for renewables to entirely eclipse coal in the U.S. and in June it is expected coal-fired generation will again surpass renewables.
Some countries have raced ahead of the US in embracing renewable energy. In Costa Rica, an incredible 95% of electricity has been generated by the renewable sector over the past four years.
As of 2016, Iceland, Norway, Ethiopia, Albania, Namibia, Kenya, Tajikstan, Uruguay and Zambia had all achieved more than 90% of their total generation through renewable sources. Some countries are able to draw on their advantageous geography to produce renewable energy.