Unlimited Clean Fossil Fuel?

If I told you that there was a potentially limitless source of fossil fuel, you would naturally want to know what the catch was. In the case of methane hydrates, a form of natural gas that has been bound up in ice crystals in the Arctic and deep ocean beds, that catch has been so large that I seem never even to have mentioned the subject in nearly five years of blogging. Hydrates are in the news this week in a very significant way, however, though the quantity in question is still quite small, compared to their ultimate potential. The US Geological Survey released a report estimating that 85 trillion cubic feet (TCF) of technically recoverable gas hydrates are accessible on the Alaskan North Slope. If produced over 20 years and combined with the conventional gas supply from the North Slope, which has been waiting for a pipeline south for many years, this deposit could supply up to a third of total US natural gas consumption. But that barely scratches the surface of the overall potential of gas hydrates.

The reason this announcement is so significant lies in the words "technically recoverable." Geologists have known about gas hydrates for a long time, and estimates of global hydrate deposits have been refined to a range of between 100,000 and a million TCF, with the best estimate of US hydrate deposits currently at 200,000 TCF. To put that in perspective, one TCF of natural gas represents about 1% of US annual total energy consumption and contains the same energy as 180 million barrels of oil or 10 billion gallons of ethanol. In other words, that 200,000 TCF estimate is the equivalent of a 2,000-year energy supply for the US, at current consumption levels, of a fuel with half the greenhouse gas emissions of coal. If we could learn enough from tapping the identified deposit on the North Slope, we might be able to exploit the much larger, less accessible deposits elsewhere--and it should tell you something that the North Slope of Alaska looks easy in this regard.

A natural gas source of that magnitude would align nicely with an energy strategy such as the Pickens Plan, employing natural gas for transportation fuel and generating electricity from wind and other renewables. It is one possible path towards much greater energy self-reliance and much lower emissions. For that matter, hydrates and other unconventional gas could ultimately provide enough fuel to displace all coal from power generation, until it can be replaced by enhanced geothermal systems, nuclear fusion, space solar power, or some other reliable and essentially limitless source of emissions-free electric power.

To put this in its proper perspective, if it were easy, we'd already be doing it. Nor are hydrates free of risks, the biggest of which could make our climate problems much worse, very quickly. That's because methane is a powerful greenhouse gas, 21 times more than CO2, and methane hydrates are only stable under certain conditions of temperature and pressure. A sudden release of a large quantity of methane from hydrates could accelerate the greenhouse effect, as may have happened in the geological past. But while any plan to mine hydrates must include rigorous safeguards against such an outcome, that risk must also be weighed against the risk that gas hydrates will naturally begin to vent their methane, if we remain on the current global emissions trend line and polar and ocean temperatures continue to increase.

There are no energy panaceas, and methane hydrates don't constitute one, either, because of their technical challenges and possible drawbacks. However, as a long-term hydrocarbon supply for energy and petrochemicals, they offer significant advantages over many forms of unconventional oil, and they could be extremely useful in a post-Peak Oil, low-emissions energy economy, as conventional oil & gas supplies deplete. I'm encouraged that the USGS sees the North Slope hydrate deposit as falling within our current technical capabilities, potentially unlocking the equivalent of 15 billion barrels of oil or roughly 900 billion gallons of ethanol.