Maintaining a reliable value of the cost of climate change

Car exhaust. Credit: © Wrangler / Fotolia

The term Social Cost of Carbon is a figure that puts a dollar value on the climate damages per ton of CO2 released, and is used by, among others, policymakers to help determine the costs and benefits of climate policies. In the latest issue of the journal Science, a group of economists and lawyers urge several improvements to the government's figure that would impose a regular, transparent and peer-reviewed process to ensure it is reliable and well-supported by the latest facts.

"By providing an estimate of the damages from an extra ton of CO2 emissions, the Social Cost of Carbon tells us how much money we should devote to mitigating emissions. It separates the efficient policies from the wasteful ones, and for this reason is an incredibly useful tool in devising climate policy," said Prof. Michael Greenstone, one of the authors of the analysis and the director of the Energy Policy Institute at the University of Chicago. "Having said that, every day we are learning more about the science behind climate change and the economic impacts it imposes. It's vital that policy keeps up as our knowledge evolves."

The researchers suggest that the value be updated routinely, specifically they recommend every five years to balance the need for incorporating the latest research with a thorough review process. Part of that process should entail a review by the National Academy of Science's National Research Council, they say, to allow outside experts to be part of the process and suggest changes. They also argue that a single Social Cost of Carbon estimate should be maintained and shared by all government agencies.

"Greenhouse gas emissions cause the same damage, regardless of whether they are emitted through car tailpipes or factory smokestacks, and no matter where in the world they come from," Greenstone said. "For this reason, one, consistently used and rigorously maintained estimate of climate damages is imperative to ensure our climate policies are providing the maximum benefits for the least costs."

William Pizer, the lead author of the study and a professor at Duke University, further emphasized this need.

"To ensure that value exists, it's important that we draw on the expertise of all government agencies, as well as independent experts in the field," Pizer said. "This level of high-quality collaboration and peer review would decrease the likelihood of political factors interfering with the process, and ensure we have the most robust Social Cost of Carbon."

The authors give an example of why such a consistent, collaborative and well-supported value is important. When the Social Cost of Carbon value used today, which was developed with a vigorous approach, is applied to the EPA's recent Clean Power Plan that limits emissions from existing power plants, the benefits of the rule vastly outweigh the damages. However, when applying a past value used by a single agency, the plan's benefits do not exceed the costs.

Additionally, Greenstone noted that the figure is not just a tool for policymakers. The courts, businesses and others use this figure to make important decisions on the impacts associated with climate change.

"The U.S. Social Cost of Carbon is becoming a focal estimate of the likely climate damages globally," Greenstone said. "It's critical that that we get this number right, because it will influence policy around the world."

Greenstone and some of his colleagues have initiated a larger project to determine an even more rigorously maintained cost of climate change at a global scale. "Our hope is that this ongoing research project will inform the periodic revisions of the Social Cost of Carbon that we advocate for in this Science article."

Source: University of Chicago

Natural gas saves water, even when factoring in water lost to hydraulic fracturing

For every gallon of water used to produce natural gas through hydraulic fracturing, Texas saved 33 gallons of water by generating electricity with that natural gas instead of coal (in 2011).

A new study finds that in Texas, the U.S. state that annually generates the most electricity, the transition from coal to natural gas for electricity generation is saving water and making the state less vulnerable to drought.

Even though exploration for natural gas through hydraulic fracturing requires significant water consumption in Texas, the new consumption is easily offset by the overall water efficiencies of shifting electricity generation from coal to natural gas. The researchers estimate that water saved by shifting a power plant from coal to natural gas is 25 to 50 times as great as the amount of water used in hydraulic fracturing to extract the natural gas. Natural gas also enhances drought resilience by providing so-called peaking plants to complement increasing wind generation, which doesn't consume water.

The results of The University of Texas at Austin study are published this week in the journal Environmental Research Letters.

The researchers estimate that in 2011 alone, Texas would have consumed an additional 32 billion gallons of water -- enough to supply 870,000 average residents -- if all its natural gas-fired power plants were instead coal-fired plants, even after factoring in the additional consumption of water for hydraulic fracturing to extract the natural gas.

Hydraulic fracturing is a process in which water, sand and chemicals are pumped at high pressure into a well to fracture surrounding rocks and allow oil or gas to more easily flow. Hydraulic fracturing and horizontal drilling are the main drivers behind the current boom in U.S. natural gas production.
Environmentalists and others have raised concerns about the amount of water that is consumed. In Texas, concerns are heightened because the use of hydraulic fracturing is expanding rapidly while water supplies are dwindling as the third year of a devastating drought grinds on. Because most electric power plants rely on water for cooling, the electric power supply might be particularly vulnerable to drought.

"The bottom line is that hydraulic fracturing, by boosting natural gas production and moving the state from water-intensive coal technologies, makes our electric power system more drought resilient," says Bridget Scanlon, senior research scientist at the university's Bureau of Economic Geology, who led the study.

To study the drought resilience of Texas power plants, Scanlon and her colleagues collected water use data for all 423 of the state's power plants from the Energy Information Administration and from state agencies including the Texas Commission on Environmental Quality and the Texas Water Development Board, as well as other data.

Since the 1990s, the primary type of power plant built in Texas has been the natural gas combined cycle (NGCC) plant with cooling towers, which uses fuel and cooling water more efficiently than older steam turbine technologies. About a third of Texas power plants are NGCC. NGCC plants consume about a third as much water as coal steam turbine (CST) plants.

The other major type of natural gas plant in the state is a natural gas combustion turbine (NGCT) plant. NGCT plants can also help reduce the state's water consumption for electricity generation by providing "peaking power" to support expansion of wind energy. Wind turbines don't require water for cooling; yet wind doesn't always blow when you need electricity. NGCT generators can be brought online in a matter of seconds to smooth out swings in electricity demand. By combining NGCT generation with wind generation, total water use can be lowered even further compared with coal-fired power generation.

The study focused exclusively on Texas, but the authors believe the results should be applicable to other regions of the U.S., where water consumption rates for the key technologies evaluated -- hydraulic fracturing, NGCC plants with cooling towers and traditional coal steam turbine plants -- are generally the same.

The Electric Reliability Council of Texas, manager of the state's electricity grid, projects that if current market conditions continue through 2029, 65 percent of new power generation in the state will come from NGCC plants and 35 percent from natural gas combustion turbine plants, which use no water for cooling, but are less energy efficient than NGCC plants.

"Statewide, we're on track to continue reducing our water intensity of electricity generation," says Scanlon.

Hydraulic fracturing accounts for less than 1 percent of the water consumed in Texas. But in some areas where its use is heavily concentrated, it strains local water supplies, as documented in a 2011 study by Jean-Philippe Nicot of the Bureau of Economic Geology. Because natural gas is often used far from where it is originally produced, water savings from shifting to natural gas for electricity generation might not benefit the areas that use more water for hydraulic fracturing.


Source: University of Texas at Austin.

The Gas-charged fluids creating seismicity associated with a Louisiana sinkhole

Natural earthquakes and nuclear explosions produce seismic waves that register on seismic monitoring networks around the globe, allowing the scientific community to pinpoint the location of the events. In order to distinguish seismic waves produced by a variety of activities -- from traffic to mining to explosions -- scientists study the seismic waves generated by as many types of events as possible.

In August 2012, the emergence of a very large sinkhole at the Napoleonville Salt Dome in Louisiana offered University of California, Berkeley scientists the opportunity to detect, locate and analyze a rich sequence of 62 seismic events that occurred one day prior to its discovery.

In June 2012, residents of Bayou Corne reported frequent tremors and unusual gas bubbling in local surface water. The U.S. Geological Survey installed a temporary network of seismic stations, and on August 3, a large sinkhole was discovered close to the western edge of the salt dome.

In this study published by the Bulletin of the Seismological Society of America (BSSA), co-authors Douglas Dreger and Avinash Nayak, evaluated the data recorded by the seismic network during the 24 hours prior to the discovery of the sinkhole. They implemented a waveform scanning approach to continuously detect, locate and analyze the source of the seismic events at the sinkhole, which are located to the edge of the salt dome and above and to the west of the cavern near the sinkhole.

The point-source equivalent force system describing the motions at the seismic source (called moment tensor) showed similarities to seismic events produced by explosions and active geothermal and volcanic environments. But at the sinkhole, an influx of natural gas rather than hot magma may be responsible for elevating the pore pressure enough to destabilize pre-existing zones of weakness, such as fractures or faults at the edge of the salt dome.

Source: Seismological Society of America