This picture taken on July 24, 2012 show

Impending Environmental Protection Agency (EPA) regulations governing utilities’ cooling water intake and discharge could force some power plants to close, according to Black & Veatch Energy Chief Executive Dean Oskvig.

Electricity production accounts for 38% of US water usage. In many cases, cooling water is drawn directly from a source such as a river or lake.

Usage is distinct from consumption – used water is returned directly to the source, while consumed water is not – mitigated water scarcity concerns. But the intake and discharge of water have generated environmental concerns of a different sort. New EPA regulations seeking to limit damage to fish and other aquatic wildlife caused by water intake mechanisms are scheduled to be finalized this June. And the agency proposed new rules governing the discharge of cooling water from power plants last month.

“There are more and more regulations coming on now about the discharge of water, having to do with temperature, and intake – protection of fish – which is going to burden once-through cooling plants,” Oskvig told Breaking Energy.  A once-cooling plant – in contrast to a closed-loop plant – uses open sources of water to condense steam, rather than specialized water-cooling facilities.

“It will put some plants out of the economic viability area,” Oskvig said.

Cooling Options

Some plants use less water than others. Nuclear, coal, biofuel and solar thermal plants’ water use is at the higher end of the spectrum, while combined cycle and integrated gasification combined cycle plants tend to use far less, according to data from Black & Veatch and the Electric Power Research Institute (link to graphic below).

Water Withdrawal by Power Plant Technology

And options exist to limit intake of large volumes of fresh water. Some power plants have been designed to either reuse wastewater, or to use very little water at all.

Oskvig gave two examples: a combined cycle gas plant in Florida which takes treated sewer effluent from a water treatment plant – “the waste from one becomes the output for the other” – and dry cooling plants, such as a project the company is currently working on at South African state-owned utility Eskom’s Kusile plant. “It has air-cooled condensers and uses 5% of the water of a conventional plant,” Oskvig said.

But these other options can be costly. In the case of dry-cooling plants, the machinery and operating costs add 10-15% to the total cost of the plant, he said. He added that the parasitic load – the power that the dry cooling machinery draws from the plant – is on the order of 10%. “In order to get the same net output, you have to build a bigger plant,” he said.

“It’s technically feasible to do these things, but they come at a cost,” Oskvig said.

For more on this subject:

Duke Energy: EPA Regulations and Natural Gas Force Industry Transformation

Electric System Reliability in Question as More Coal Plants than Expected Retire