Challenging the Water-Energy Relationship

Challenging the Water - Energy Relationship

Ecoal, Vol.76, November 2011

Along with energy security, water security is expected to be a major geopolitical challenge in the coming decades. According to the OECD 2.8 billion people, or almost half of the world's population, live in areas of high water stress. This number is expected to increase by 39% within the next two decades.

Energy generation is generally associated with high water consumption and may have implications for water quality. Cooling systems represent the highest proportion of water consumption in energy generation. This makes water an essential element of the energy generation process. In fact, the higher the reliance on water for cooling purposes, the higher the risk that power generation output might be affected during hot summers or droughts.

Electricity generation

Reports by the International Energy Agency (IEA) and the World Policy Institute (WPI) show that hydro, geothermal, nuclear and concentrated solar power are the most water intense among the existing electricity generation technologies. Generating electricity in coal-fired power plants also requires a significant amount of water for cooling purposes.

In fact coal-fired power plants consume twice as much water than gas-fired power plants and around 30% less than nuclear power plants. Using integrated gasification combined cycle (IGCC) technology at coal-fired power plants can reduce water consumption by half. IGCC plants consume around the same amount of water as natural gas plants; that is four times less than solar thermal and seven times less than geothermal energy. Renewable energies such as wind or solar photovoltaic have virtually no impacts on water.

CCS plants are estimated to consume 30% to 100% more water than unabated power plants, mainly because of the efficiency penalties which require larger energy input and, as a result, larger cooling systems. The IEA statistics show that at a high estimate water consumption of CCS power plants could be as high as 4000 L/MWh, which is more than any other generation technology, including concentrated solar power (CSP) and nuclear.

Fuel extraction

Mining coal is just as water intense as extracting natural gas or oil and is responsible for around a tenth of water consumption across the entire chain of energy production and electricity generation.. However, according to the WPI hydraulic fracking - the method used to extract natural gas from shale formations, might consume as much as seven times more water than conventional gas extraction and there is a possibility that nearby drinking water reservoirs might get contaminated during the process of shale gas extraction.

Future challenges

According to the Stockholm International Water Institute, global demand for water could outstrip supply by 40% by 2030 if the current consumption trends are not changed. In the light of the forthcoming Rio +20 Summit, the Institute calls among others for a 20% increase in water use efficiency in energy production by 2020.

There are a number of good examples of responsible water management within the international coal industry. The EMalahleni water reclamation plant in South Africa, set up jointly by Anglo American and BHP Billiton, allows the companies' local operations to be self-sufficient in terms of water consumption and it also supplies 20% of water consumed by the local town.

Further information:www.iea.org and www.worldpolicy.org