Dec. 18, 2014

Natural gas from hydraulic fracturing generates income and, done well, can reduce greenhouse gas emissions, air pollution and water use compared to coal and even nuclear energy. However, widespread use of natural gas from fracking could slow the adoption of wind, solar and other renewables and, done poorly, release toxic chemicals into the environment.

On Dec. 18, Stanford University Professor Robert Jackson discussed how to minimize the water and air impacts of fracking and other unconventional energy-extraction techniques at the 2014 fall meeting of the American Geophysical Union (AGU) in San Francisco.

Professor Robert Jackson

"Switching from coal to natural gas for electricity generation will reduce sulfur, nitrogen, mercury and particulate pollution regionally," said Jackson, the Kevin and Michelle Douglas Professor of Environment and Energy at the Stanford School of Earth Sciences. "But natural gas extraction can also increase volatile organic compounds and other air toxins locally, creating a potential health threat. One key message is that best practices matter a lot for environmental stewardship, and some companies have stronger best practices than others."

In his talk, Jackson discussed recently published and new data on water contamination in the Marcellus and Barnett shales of Pennsylvania and Texas, respectively. Based on research to date, primary threats to water resources come from surface spills, wastewater disposal and drinking-water contamination through poor well integrity.

In terms of air quality, Jackson and his colleagues have found that methane leakage is a significant problem in the U.S. natural gas industry. Natural gas power plants typically emit less carbon dioxide, a major contributor to global warming, than coal-fired plants. But methane, the main ingredient in natural gas, is 34 times more effective at trapping heat than carbon dioxide over a 100-year time scale, according to a recent report by the Intergovernmental Panel for Climate Change.

According to Jackson, critical needs for future research on unconventional energy extraction include data on the impact of greenhouse gases and air pollution on ecosystems and human health, the potential contamination of surface and groundwater from drilling and spills, and the frequency of well-integrity failures. In addition to benefiting health and mitigating climate change, improving the natural gas infrastructure would also provide significant economic and job opportunities, he added. 

Forest carbon projects

In another AGU talk on Dec. 15, Jackson discussed research assessing the energy exchanges and climatic impact of vegetation replacement across North America. The work compares satellite-derived albedo, a measure of surface reflection; land surface temperature; and evapotranspiration between adjacent vegetation types, specifically grasslands, croplands and different forest types.

Recent international climate talks have focused on the potential of reforestation and afforestation – planting trees in an area where there was no forest previously – to slow global warming. Increasingly, though, science is showing that planting more trees and increasing forest conservation can provide benefits beyond carbon storage, and that carbon-centric accounting is, in many cases, insufficient for climate mitigation policies.

"To be truly effective, forest carbon projects need to consider factors beyond carbon storage," said Jackson, a senior fellow at the Stanford Woods Institute for the Environment and the Precourt Institute for Energy. "Researchers are still working on how best to do that."

Jackson and his fellow researchers have determined, among other findings, that where afforestation or reforestation occurs, deciduous broadleaf trees are likely to produce stronger cooling benefits than evergreen needleleaf trees provide in temperate ecosystems. They've also found that forestry activities will have the most climatic benefits at locations where background albedo prior to landscape change is low, snow cover is minimal, cloud cover is high and soil water is ample.

In his AGU talk, Jackson discussed how forests can help slow the buildup of greenhouse gases in the atmosphere while also providing beneficial biophysical feedbacks, and how many extra resources, including water and nutrients, may be needed to achieve this carbon storage and climate benefit.

Ker Than (Stanford School of Earth Sciences) and Mark Shwartz (Precourt Institute for Energy) contributed to this Stanford News Service article.