Twenty years ago on page 6 of the January 1988 edition of Power Engineering magazine, a full-age ad introduced “POWER-GEN ‘88” to the world. The inaugural event, which grew to become POWER-GEN International, was held at the Orlando Convention Center from December 6-8. The event covered fossil and solid fuel power generation, including coal, oil, natural gas, municipal solid waste and other waste fuels. “Paper abstracts are invited,” the ad read. That opened the floodgates, which, over the next 20 years, would see thousands of papers researched, written and presented at the world’s largest and most prestigious exhibition and conference for the power generation industry.
Power Engineering magazine has been PGI’s flagship media sponsor since the beginning 20 years ago. This year to celebrate PGI’s 20th anniversary we’ll take a look back at some of the issues and events that were making news. A lot of the same issues continue to make news today.
Think dry cooling remains only a technology of the future? Think again. An article in the October 1988 issue of Power Engineering asked whether dry cooling was a mature technology. The author, John Bartz of the Electric Power Research Institute, said that while dry cooling was a common system overseas, its uses in the United States were limited at best.
The article began by reporting that as of 1988, 30 percent of operating power plants used cooling towers. More than 75 percent of plants being built were expected to use towers because suitable ocean, lake and river sites for once-through cooling were becoming increasingly scarce.
At the time, two water conserving cooling system installations were in place on plants larger than 100 MW. At the 330 MW Wyodak plant in Wyoming, steam was ducted to and condensed in air-cooled hear exchangers. At the 466 MW San Juan 3 power plant in New Mexico, hot water from the steam condenser was cooled in an air-cooled heat exchanger in a hybrid wet/dry tower. Both plants had been operating for a decade and both were chosen for dry cooling because of a lack of sufficient water in the area.
Mr. Bartz wrote that the future for dry cooling in the United States was unclear. Projections dating from the 1970s pointed to severe water constraints for power plant cooling. Those warnings failed to materialize, however, due largely to slower-than-expected rates of new construction.
He said a review of the status of dry cooling technology did not offer utility planners a reason for solid confidence in the technology’s maturity. With around 1 GW in operation (and most of it on a small scale) U.S. utilities seemed hesitant to consider dry cooling because of reliability and cost concerns. From a worldwide view, however, some 20 GW of dry cooling was to be in commercial operation by the early 1990s, suggesting that maturity was occurring in the technology, Mr. Bartz wrote.
He continued, writing that a principal research and development effort in dry cooling was a project aimed at substantially reducing total costs of water-conserving cooling systems in anticipation of the day when some utilities would not have a wet cooling option. A 17 MW advanced wet/dry cooling demonstration showed that anhydrous ammonia could be used to reject heat from the steam condenser to air-cooled heat exchangers in a safe and reliable manner and with substantial projected cost savings compared to the corresponding commercial alternative.
An apparently promising technology variation was an ammonia bottoming cycle being demonstrated by Electricite de France at 20 MW scale. In the system, the low-pressure steam turbine stage was replaced by an ammonia loop and ammonia expander that was to reject heat to an air-cooled ammonia condenser. This cycle, when compared to a conventional low-pressure turbine with wet cooling, offered the advantages of improved heat rate, elimination of freezup concerns and the benefits of water conservation.
EPRI’s future role in implementing dry cooling technology was said to depend on new plant construction evolution and constraints on water. “In any case,” the article said, “the search will continue for means to reduce power production costs in cases where wet cooling systems are not a utility option.”