Wednesday, July 9, 2014

Oklahoma Earthquakes Induced by Wastewater Injection by Disposal Wells, Study Finds

House damage in central Oklahoma from the magnitude 5.6 earthquake
on Nov. 6, 2011. Credit: Brian Sherrod, USGS

The dramatic increase in earthquakes in central Oklahoma since 2009 is likely attributable to subsurface wastewater injection at just a handful of disposal wells, finds a new study to be published in the journal Science on July 3, 2014.

The research team was led by Katie Keranen, professor of geophysics at Cornell University, who says Oklahoma earthquakes constitute nearly half of all central and eastern U.S. seismicity from 2008 to 2013, many occurring in areas of high-rate water disposal.

"Induced seismicity is one of the primary challenges for expanded shale gas and unconventional hydrocarbon development. Our results provide insight into the process by which the earthquakes are induced and suggest that adherence to standard best practices may substantially reduce the risk of inducing seismicity," said Keranen. "The best practices include avoiding wastewater disposal near major faults and the use of appropriate monitoring and mitigation strategies."

The study also concluded:

  • Four of the highest-volume disposal wells in Oklahoma (~0.05% of wells) are capable of triggering ~20% of recent central U.S. earthquakes in a swarm covering nearly 2,000 square kilometers, as shown by analysis of modeled pore pressure increase at relocated earthquake hypocenters.
  • Earthquakes are induced at distances over 30 km from the disposal wells. These distances are far beyond existing criteria of 5 km from the well for diagnosis of induced earthquakes.
  • The area of increased pressure related to these wells continually expands, increasing the probability of encountering a larger fault and thus increasing the risk of triggering a higher-magnitude earthquake.

"Earthquake and subsurface pressure monitoring should be routinely conducted in regions of wastewater disposal and all data from those should be publicly accessible. This should also include detailed monitoring and reporting of pumping volumes and pressures," said Keranen. 'In many states the data are more difficult to obtain than for Oklahoma; databases should be standardized nationally. Independent quality assurance checks would increase confidence. "

Source: The above story is based on materials provided by Cornell University.

Journal Reference: K. M. Keranen, M. Weingarten, G. A. Abers, B. A. Bekins, and S. Ge. Sharp increase in central Oklahoma seismicity since 2008 induced by massive wastewater injection. Science, 3 July 2014 DOI: 10.1126/science.1255802

Tuesday, July 1, 2014

World's First Industrial-Scale Waste-to-Biofuels Facility

By Ben Coxworth | June 20, 2014

Thanks to its extensive composting and recycling facilities, the city of Edmonton, Canada is already diverting approximately 60 percent of its municipal waste from the landfill. That figure is expected to rise to 90 percent, however, once the city's new Waste-to-Biofuels and Chemicals Facility starts converting garbage (that can't be composted or recycled) into methanol and ethanol. It's the world's first such plant to operate on an industrial scale, and we recently got a guided tour of the place.

The process begins with garbage trucks dumping their loads on the tipping floor at the Integrated Processing and Transfer Facility. The trash is manually and mechanically sorted, with things like appliances being set aside for electronic parts recycling and e-waste disposal, while organic matter heads off to the Composting Facility.

Recyclable materials are already pre-separated by citizens as part of the city's blue bag program. They avoid the garbage stream entirely, going straight to the Materials Recovery Facility for recycling.

Soon, though, high-carbon materials such as wood, fabric and discarded plastic will be getting shredded into Refuse Derived Fuel (RDF), also known as "garbage fluff." It will be transferred to the Waste-to-Biofuels and Chemicals Facility, which is owned and operated by Enerkem Alberta Biofuels.

There, it will be heated in a low-oxygen atmosphere. This will cause its chemical bonds to break (without the material actually burning), releasing their carbon and hydrogen content to form what's known as syngas. This will in turn be cleaned up and converted into chemical products and biofuels – such as methanol and ethanol.

The Waste-to-Biofuels and Chemicals Facility is scheduled to go online in the next several weeks. It is ultimately expected to convert 100,000 tonnes (110,231 tons) of municipal solid waste into 38 million liters (10 million gallons) of biofuels and chemicals annually.

You can see our video tour of the facility below, conducted by the Edmonton Waste Management Centre's Education Programs Co-ordinator, Garry Spotowski. There are also photos of the process in the gallery.

The video can be viewed at: