Natural Gas & The Low-Carbon Economy


be added to factories, commercial buildings, and even family homes. Located within the local power distribution system, micro-power plants avoid the need to add expensive and hard- to-site transmission lines and – unlike ‘baseload’ coal and nuclear plants – can easily be turned on and off as needed to meet fluctuating power demand. Compared with electricity from a conventional power plant and heat from a separate gas- fired furnace, a cogeneration system typically has an efficiency of between 65 and 80% and would allow even greater emissions reductions than combined-cycle plants. Volkswagen announced plans in 2009 to produce 10,000 miniature 20-kilowatt gas-fired power plants per year, based on the internal combustion engines it uses in its Golf automobiles. These units are designed for use in individual residences and will operate at up to 94% efficiency, providing heat, hot water, and electricity. Dubbed “schwarmpower” this network of tiny power plants could, within a decade, provide 2,000 MW of capacity (equivalent to two nuclear plants) that will be digitally controlled and used to back up the variable wind power that already provides some 40% of the electricity in three German states. The prospect of widespread deployment of small-scale solar


power plants in and near the world’s cities in the years ahead will likely spur growing interest in micro-power plants using natural gas. As small- scale solar and gas generators are integrated into local, low-voltage power systems, both will require new laws that allow small businesses and consumers to access the local grid at a competitive price.


Overcoming Environmental Challenges While natural gas has many environmental advantages over


the other fossil fuels, it is not without problems of its own. The rapid development of unconventional gas in recent years has raised a host of environmental and health concerns, generating extensive controversy at the local, state, and national levels. Gas development has been particularly controversial in the northeastern states of Pennsylvania and New York, where state regulators and citizens who had no experience with oil and gas development were ill-prepared for the unconventional gas boom. Communities that welcome the jobs and income that are flowing from the new industry are also struggling with the disruptions and environmental problems that often accompany expanded gas development. To extract natural gas from tight sand, shale, and some


coal bed formations, engineers utilize two key technologies: horizontal drilling and hydraulic fracturing. Shale gas


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extraction is begun by drilling a vertical well to the depth of the reservoir, then gradually turning the drill bit 90 degrees until it is oriented parallel to the productive layer. Horizontal wells offer greater contact area with the reservoir than vertical wells, providing an important boost to production in strata that have low permeability. In addition, they greatly reduce the surface impact of drilling operations because engineers can drill multiple wells from a single well pad and extend those wells laterally for thousands of feet. According to estimates from the US Departments of Interior and Energy, in the Fayetteville Shale a four-well horizontal drilling pad with roads and corridors would disturb about 7.4 acres on the surface, whereas the 16 vertical drilling pads that would be necessary to produce the same square mile of the formation, together with roads and utility corridors, would disturb some 77 acres. To free-up the gas that is tightly bound in the impermeable


While natural gas has many


environmental advantages over the other fossil fuels, it is not without problems of its own


rock, developers typically inject wells with millions of gallons of water mixed with chemical additives and sand under high pressure. The fracturing or ‘fracking’ fluid widens and props open tiny fractures in the shale, increasing the reservoir’s permeability and allowing gas to escape more freely. Fracking fluids can contain small concentrations of toxic chemicals that improve the effectiveness of the procedure, including biocides, corrosion inhibitors, and thickening agents. No federal law currently requires companies to disclose the


chemicals used in fracturing fluids – a condition that companies argue is necessary to protect their trade secrets. Once fracking fluid has come into contact with the rock


formations through which the wellbore travels, it can mix with methane, highly concentrated salts, and naturally occurring radioactive materials (NORM). While some portion of injected fracking fluid remains underground, produced water brought up from the target formation must be disposed of safely. Depending on the state regulations in place, companies may be required to re-inject produced water into disposal wells or to send it to wastewater treatment facilities, where it must generally be transported in tankers. If a leak or spill occurs at any point during the production, transportation, or disposal processes, produced water can pollute groundwater and surface waters. Similarly, the volumes of produced water generated by increased levels of gas drilling can overwhelm wastewater treatment facilities, as occurred in Pennsylvania’s Monongahela River during the fall of 2008. As gas production expands to new regions, improving wastewater disposal and treatment practices and capacity will be critical.


worldPower 2010


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