If the United States — and by extension the world — has a hope of shifting to a low-carbon future, that shift will almost certainly involve burning a vast volume of natural gas. So concludes an assessment by researchers at the Massachusetts Institute of Technology in Cambridge, who estimate that the US could reduce greenhouse gas emissions from the electricity sector by at least 10 percent virtually overnight by shutting down inefficient coal-fired plants and ramping up gas-powered generators.
"In a carbon-constrained future, gas plays a particularly important role as a bridge," says Ernest Moniz, who headed the project as director of MIT's Energy Initiative (MITEI).
Burning natural gas to generate electricity emits roughly half as much carbon dioxide as coal. Following up on earlier reports covering nuclear power and coal, Moniz and his colleagues took an in-depth look at natural gas supplies and the role they could play as the world moves toward a low-carbon energy system. The new report on The Future of Natural Gas comes at a time when 'hydraulic fracturing' technologies have opened up huge reserves of gas associated withshale formations across the US. The technique, which involves injecting high-pressure fluid into rock to open cracks and release gas, has also raised environmental concerns because of contamination risks to aquifers and surface water.
"The environmental risks are manageable but challenging," says study co-chair and MITEI Visiting Engineer Anthony (Tony) Meggs who is a retired group vice-president of technology for BP. He notes that a typical high-volume 'frac job' may return 50 to 100 thousand barrels of fluid to the surface, which would require safe disposal to avoid contamination. To safeguard against environmental problems, the report calls for transparency in gas-field practices, integrated water use and disposal plans and mandatory disclosure of the ingredients in fracture fluids.
Fuelling up
The MIT study pegs the US supply at around 2,100 trillion cubic feet, which is enough to fuel the country for roughly 92 years at 2009 consumption levels. That puts the United States behind only Russia and the Middle East as a whole in terms of supply — a dramatic transformation compared to less than a decade ago, when falling production rates triggered price spikes and speculation that the US would soon be forced to begin importing large quantities of liquefied natural gas. According to the report, the greatest potential for growth is in the electricity sector, although natural gas could also be deployed to fuel fleet vehicles, buses and long-haul trucks in the transport sector.Significantly, the study found that with a 'level playing field' approach in which the relative prices of various energy sources are set to reflect the carbon dioxide they produce, gas could almost entirely displace coal burning in the US by 2035. Under such a policy regime, natural gas consumption would begin to taper off by 2050 because of the need to limit all sources of carbon, says Moniz, "but for a good period of time, if we are going to crank down on carbon emissions, we need natural gas to play a critical role."
As a concrete example, the study includes an in-depth modelling analysis of the Texas electric system, which is largely self contained, and found that a 22 percent reduction of greenhouse emissions from the power sector was achievable in the short term, with similar opportunities available across the United States.
Applying leverage
"Gas is where you have the most leverage over climate on the energy supply side right now, and I think this report does a good job of emphasizing that," says Mark Thurber, associate director for research at Stanford University's Program on Energy and Sustainable Development. Although there are no technical barriers, the political challenge is getting the monetary incentives or regulations in place to help gas displace coal, Thurber says. "In my mind, the next discussion should be, 'Okay, well how do we do it?'"
No comments:
Post a Comment