For several years, many voices, including Texas energy baron T. Boone Pickens, have been touting natural gas as the best energy source to form a bridge between the current fossil-fuel economy and a renewable energy future. Proponents contend that not only is natural gas a cleaner-burning fuel than coal, producing lower greenhouse gas emissions, but that reserves of natural gas are far greater than previously believed because of vast reserves trapped throughout the US - and around the world - in huge underground formations of shale.
Earlier this month, Britain’s New Scientist magazine published an article about shale gas entitled, “Wonderfuel: Welcome to the Age of Unconventional Gas.” Last month, the Wall Street Journal ran its own op-ed ode to shale gas: “Shale Gas Will Rock the World.” The author, Amy Myers Jaffe - a fellow in energy studies at Rice University - wrote, “I am convinced that shale gas will revolutionise the industry - and change the world - in the coming decades”. She even suggested that the abundance of natural gas in shale deposits worldwide will slow the transition to a renewable energy future.
“It may be a lot harder to persuade people to adopt green power that needs heavy subsidies when there’s a cheap, plentiful fuel out there that’s a lot cleaner than coal, even if gas isn’t as politically popular as wind or solar,” Jaffe wrote.
But after spending the last few years analysing all the sources of energy available to the United States, I am convinced that the choice is clear: based on existing technology, solar and wind are the only practical alternatives that would provide America with abundant, independent energy with few undesirable environmental and human-health effects. While shale gas is estimated to be abundant, and the proponents tell you that it will be easy to extract the gas with few environmental effects, in fact this is a relatively experimental technology that has potentially large environmental risks.
The water pollution concerns alone should be sufficient to make the US and other countries rethink future reliance on shale gas. Separating the gas from the shale, a process known as hydrofracturing, involves forcing a mixture of water, chemicals, and sand at high pressure down a well bore and into rock formations, creating small fractures that release the trapped gas. The process uses a huge amount of water - the New York State Department of Environmental Conservation estimates as much as 1 million gallons per well - at a time when water is already a limiting and precious resource.
Second, hydraulic fracturing fluid may come back to the surface, or near enough, to affect groundwater supplies. This fluid is a mixture of chemicals including friction reducers, biocides to prevent the growth of bacteria that would damage the well piping or clog the fractures, a gel to carry materials into the fractures, and various other substances. Returning to the surface, it could also bring other environmentally damaging materials, such as heavy metals.
Advocates for shale gas claim that these effects will be minor. Others, including those in charge of water supplies, are not persuaded. In Pennsylvania, wells claimed to be safe have leaked natural gas into local domestic water supplies, with the gas bubbling out of faucets. Also in Pennsylvania, fracturing fluids have leaked before they have been sent underground and have also contaminated drinking water. These problems suggest that returning fracturing fluids to the surface could cause similar problems on a large scale.
That shale gas exists in abundance - in the US, Europe, Australia, China, South Africa, and other regions - is beyond question. New Scientist reported that enough recoverable shale gas exists to meet the world’s needs for 60 years. The Marcellus Shale region in the eastern US reportedly contains enough shale gas to meet US natural gas demand for a century. The Massachusetts Institute of Technology released a report last week forecasting that, in part because of the exploitation of abundant shale gas reserves, natural gas will go from making up 20 per cent of the US’s energy supply today to 40 per cent within several decades.
But what is the reality behind the optimistic claims for shale gas? The US Geological Survey lists natural gas “reserves” - the amount believed to be in the ground - in four categories: readily available with current technologies, which accounts for only 1 per cent of the known natural gas in US territorial limits; technically recoverable (5 per cent); marginal targets for accelerated technology (6 per cent); and unknown but probable (84 per cent). Shale gas shares the fourth category with coal gas and methyl hydrates. The latter are a kind of water ice with methane embedded in it and occur only where it is very cold, in Arctic permafrost and below 3,000 feet in the oceans.
In researching how best to make the transition to the green energy future, one of the first calculations I made was to find out how long the natural gas in each of the four categories would last if we obtained it independently - that is, only from US territory. I was shocked by the result: just using our 2006 rates of use of natural gas consumption - not including any major transition to fueling our cars and trucks - the “readily available” gas within the United States would be exhausted in just one year. That, plus what is called “technically recoverable” gas, would be gone in less than a decade. What is termed “unknown but probable” would last about a century.
This means that any significant increase in our consumption of natural gas will have to come from the “unknown but probable” reserves, much of which will be from formations of shale, a sedimentary rock formed from muds in which bacteria released methane. Most of this gas is so deep underground or otherwise not very accessible that nobody is really sure that we can get at a lot of it, or of how high an environmental price we must pay to retrieve it.
Currently available wind and solar energy technologies, on the other hand, are up to the job right now. There just aren’t enough wind and solar installations, so today they provide less than 1 per cent of the nation’s energy. We will need to rapidly scale up, so that by 2050 we can receive the majority of our energy from wind and solar power. That’s an enormous task. The US Census Bureau forecasts that our population will reach 440 million by 2050 - nearly a 50 per cent increase from today. That’s 150 million more people, each hoping to live at the standard of living we have grown accustomed to. When that happens, the amount of fossil fuels we use today, and which provide 86 per cent of America’s energy, would provide those 440 million with less than two-thirds the energy they would need, if per-capita energy use remains the same as today.