For both traditional and emerging energy industries, there are water supply, water quality impact, and wastewater discharge issues. To understanding water issues associated with energy we need to understand how these concerns play out in each energy industry. For example, within the petroleum industry, the amounts of water used and water quality impacts vary from exploration and production on through transport (e.g., oil tankers and trucks), gas processing and oil refining, power generation, retail for gasoline (gas stations), and the various other petroleum end uses.
To meet increasing energy demands and provide greater energy security through domestic energy production, there has been considerable activity in the development of unconventional fossil energy sources, including oil sands, oil shale, and shale gas. New technologies have made unconventional fossil energy more cost-effective, especially as wellfields for conventional oil and gas supplies become depleted.
There are many opportunities for reusing water and using impaired quality water (e.g., brackish water or treated effluent) in fossil fuel production. Some municipal and agricultural water users have arrangements with oil and gas producers and refineries to provide supplies of treated effluent. However, reclaimed water usually contains high concentrations of total dissolved solids (TDS), which can cause scaling on system pipes and otherwise impact operations. In order for lower quality water to be reused, it may be necessary to reduce salinity by adding fresh water, referred to as “make-up” water. Water treatment methods, such as reverse osmosis, are energy intensive and require brine disposal.