In this post, I want to explore what exploitation of shale gas might imply for our efforts to transition to a low-carbon economy.
As a thought experiment, if we were to suddenly replace all the UK's coal consumption with natural gas, we would reduce greenhouse gas emissions by 42 million tonnes, a saving of nearly 10% from the national footprint total of 458 million tonnes CO2e.
Leaving aside the potential environmental impact of extracting this much shale gas, could we do it? One would think so, judging from breathless headlines like this one in the UK from The Times:
Let's dig into that "43 years" statistic.
The Times article summarizes the findings from a British Geological Survey (BGS) report on the Bowland-Hodder Shale Formation in northern England. According to the BGS, the mid-range estimate for the total gas in place in the Bowland Shale Formation is 1,329 trillion cubic feet (37.6 trillion cubic meters). However, not all of that gas will be recoverable at a reasonable price using foreseeable technology. A reasonable guess might be that 10% will be recoverable - call it 130 trillion cubic feet.
2012 gas consumption in the UK was approximately 3 trillion cubic feet - a figure that has actually declined slightly since 2000, as utilities burn more coal to produce power.
Divide the recoverable gas estimates (130 tcf) by current consumption (3 tcf/year) and you get 43 years. Not exactly cutting edge analysis, but easy to explain.
But is this number useful for anything besides headlines?
The first assumption we might question is that gas consumption will remain constant for the next four decades. In the U.S., an influx of cheap gas has encouraged utilities to reduce coal consumption and shelve plans for new coal-fired generation; gas consumption increased by one-third in less than a decade. If, as we expect, shale gas in the UK is cheaper than conventional gas supplies, gas consumption will rise to displace at least some of the UK's coal-fired power plants. If gas were to completely replace coal and energy consumption otherwise stays flat, natural gas use could rise by nearly 50%, as indicated in the EIA chart below:
However, the Office of National Statistics expects the country's population to rise 30% over the next four decades. Without significant efforts to improve reduce energy demand and shift to renewable energy sources, this projected population increase makes the assumption of constant gas demand even more untenable.
At this point in the analysis, we are piling guesses on top of guesses. Coming back to our original question, yes, we could completely displace UK coal consumption and drive significant emission reductions, but not for as long as the headlines would have you believe.
And what happens once we've used up that shale gas bounty? Either we lurch back to a heavy dependence on coal, causing greenhouse gas emissions and air pollution to skyrocket, or we switch to lower carbon sources of power like PV, wind, wave, and geothermal - or nuclear.
Interestingly, it would likely take 15-20 years to fully build out renewables on a truly massive scale, along with the electricity transmission and smart grid infrastructure required to make best use of decentralized and intermittent renewable resources. Likewise, it would probably take 20-30 years for nuclear power to stage a significant comeback in the United Kingdom. Whether we employ renewables, nuclear or both is an important debate, but on for another day.
The shale gas revolution, should we choose to exploit it, has the potential to buy us some time. If we can resolve the far-from-trivial environmental and other challenges facing hydraulic fracturing, we can achieve significant greenhouse gas emission reductions today, even as we build a longer-term low-carbon energy infrastructure for tomorrow.
