Energy Use and Water Resources Impacts

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Energy Use and Water Resources Impacts

Although fossil fuel use and consequent CO2 and gas emissions are widely debated, fossil fuels’ dependency on water and its adverse impacts on water availability and water quality are not fully discussed.

daFuJqz.jpgAccording to the U.S. Energy Information Administration, at present, fossil fuels contribute more than 80 percent (petroleum 36.2 percent, natural gas 29 percent, coal 16.1 percent) of energy use in the U.S., and only 20 percent comes from renewable energy sources (nuclear 8.5 percent, biomass (plant or animal) 4.8 percent, hydroelectric 2.4 percent, wind 1.9 percent, solar 0.5 percent and geothermal 0.2 percent).

Fossil fuel use and consequent carbon dioxide and methane gas emissions are widely debated as major causes of climate change.

However, fossil fuels’ dependency on water and its adverse impacts on water availability and water quality are not fully discussed.

Fossil fuels impact water resources both during energy extraction process and during thermoelectricity generation. According to a 2009 USGS report, 410 billion gallons of water are withdrawn from U.S. rivers, lakes and groundwater on a daily basis.

Thermoelectric power generation is the largest water user (201 billion gallons/day or 49 percent of total withdrawal), followed by crop irrigation (128 billion gallons/day or 31 percent of total withdrawal) and public domestic water consumption (11 billion gallons/day or 11 percent of total freshwater withdrawal).

In coal production, water is used during mining operations, coal transport and storage, refining process, dust suppression and during post-mining activities such as land reclamation and revegetation. Water is a major component of natural gas and oil extraction — large volumes of water are withdrawn when gas and oil are extracted, but this water is mostly re-injected into the aquifer (albeit of questionable quality). Water is also used in the oil refinery process. And as noted above, large volumes of water are used during thermoelectricity generation.

Mountaintop surface and strip mining operations pose significant threats to water resources. These operations expose coal seams for extraction and, often, dispose the removed overburden (called spoil) in adjacent “valley fills.”

The result is destruction of natural topography, elimination of natural vegetation, punctured groundwater aquifers and degradation of surface waters and associated ecosystems. Acid mine drainage from active or abandoned mines seeping into stream/rivers and groundwater is another significant threat to human health and ecosystems. Potential coal ash (from power plants) pond spills into natural water bodies are major environmental concern.

At present, natural gas is promoted as a clean and inexpensive energy source and is replacing coal for electricity generation. Levels of CO2 emissions for coal and natural gas are, respectively 2.117 and 1.314 pounds/kWh of power generated. Compared to coal, natural gas extraction and natural gas-fired power plants are more water efficient. However, recent studies show the significant methane leakage from natural gas wells offsets natural gas advantage over coal in reducing climate change impact.

Furthermore, using hydraulic fracturing (fracking) technology to extract natural and shale gas (oil as well) diminishes the advantage of developing natural gas. Fracking typically involves injecting water, sand and (or) chemicals under high pressure into a bedrock formation via a well. There is strong evidence on fracking’s adverse impact on groundwater quality and availability.

Yuqt4jM.jpgMajor renewable energy technologies that generate electricity include nuclear energy and hydropower.

Nuclear electricity generation is very water-intensive. Increasing highly water efficient hydropower generation is impeded by land availability to impound water and the ecological impacts of dams and impoundments.

Solar thermoelectric power is the most recent significant renewable energy source. This process also uses water for steam generation, as a coolant and cleaning purposes.

Bioenergy or biomass is a promising renewable energy for generating heat, electricity and transportation fuels (biofuels), and there are many successful projects. A notable exception is corn and soy-based biofuel and ethanol production. These are highly water-intensive because significant water is used for irrigating agricultural fields.

Geothermal power technology — energy extracted from the natural heat stored beneath the Earth’s surface by harnessing the steam – is water efficient. Since the availability of geothermal energy is localized, it can be considered as a valuable decentralized renewable energy source where available.

Water is a limited resource. Water demand for energy production and electricity generation is increasingly in competition with potable water demand and food production. To cope with this challenge, energy conservation and developing renewable energy technologies with high water use efficiency are critically needed.

This can be accomplished by adopting, where feasible, a multitude of decentralized and water-efficient renewable energy technologies such as wind, solar photovoltaics, geothermal, bioenergy, micro-hydro and other developing innovative energy technologies. Policy and economic incentives should support this challenge.

Blog by Tamim Younos

Source: Roanoke

*Tamim Younos | Younos is a water scientist and founder and president of the Green Water-Infrastructure Academy, Washington, D.C. and member, board of directors, the Cabell Brand Center, Roanoke. He lives in Blacksburg.

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