Many environmentalists are staunchly against the idea that natural gas can act as a bridge fuel to a renewable future. Actor Mark Ruffalo echoed the sentiments of many environmentalists when he wrote:
"In order to promote natural gas consumption, the oil and gas industry convinced many governments (and environmental organizations) that it is a 'bridge fuel.' The idea was that natural gas could get the country off coal while renewable energy is developed. Since natural gas burns cleaner than coal at power plants, the case was made that it is better for the climate. But science has shown that far from being a bridge, natural gas and of the practice fracking represent a death knell for our climate."
Since the turn of the century, a revolution has been underway in the power sector. Coal's share of power production has declined sharply. It appears that renewables are the future. But what role should natural gas play in reaching that future? Let's look at the data.
By the Numbers
According to data from the Energy Information Administration (EIA), in the year 2000, 71% of U.S. electricity generation was derived from fossil fuels. By 2017 the fossil fuel share had fallen to 63%.
But the overall decline in fossil fuels is entirely because of a move away from coal for power generation.
Coal's share of U.S. electricity generation between 2000 and 2017 fell from 51% to 30%. Renewables get a lot of credit for this decline, but the truth is that natural gas took most of coal's market share. Over the past 17 years, the natural gas share of power production doubled from 16% to 32%. Natural gas is now the largest source of power in the U.S.
Renewables have grown as well. The total renewable share rose from 9.5% to 17%, but hydropower has always been responsible for the largest renewable contribution. In 2000 hydropower accounted for 275 billion kilowatt-hours (kWh) of electricity. By 2017, that was just a bit higher at 300 billion kWh. But modern renewables like wind and solar power soared from nearly nothing in 2000 to 300 billion kWh in 2017.
Still, that is less than half the gains made by natural gas.
From 2000 to 2017, power generated by coal fell by 700 billion kWh. Meanwhile, at the same time natural gas generation increased by 700 billion kWh.
Falling Carbon Dioxide Emissions
The impact of the huge drop in coal can be clearly seen in the emissions data.
First, let me explain why coal has higher associated carbon dioxide emissions. Fossil fuels contain two different elements that produce energy: carbon and hydrogen. When carbon burns, it forms carbon dioxide. When hydrogen burns, it forms water vapor. Coal has a much higher concentration of carbon, whereas natural gas has much more hydrogen. Thus, when natural gas is burned, it produces relatively fewer carbon dioxide emissions.
According to the BP Statistical Review of World Energy, the U.S. has reduced carbon dioxide emissions by 639 million metric tons per year since 2000. This leads all countries by far in reducing carbon dioxide emissions. Far behind in second place was the U.K., where emissions dropped by 165 million metric tons per year.
At the same time China, by contrast, increased its carbon dioxide emissions by a whopping 6.8 billion metric tons per year, primarily a result of ~170% increases in both oil and coal consumption.
Thus, those who wish to debate whether natural gas should be a bridge between a coal-fired past and a renewable future are missing the point. It is already serving as that bridge.
In the next article, I will address how long that bridge might be, and how the U.S. model could serve as a model for the rest of the world.
Date: Sep 3, 2018