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HEA’s steam dream approaches reality

Posted: May 7, 2013 - 4:36pm
Photo by Rashah McChesney, Morris News Service - Alaska
Bob Day, power production manager at Homer Electric Association’s Nikiski power plant, gives a tour of the facility May 1.

Bob Day, Homer Electric Association power production manager, gets visibly excited when he talks about the technology behind the utility’s new Nikiski Combined Cycle Conversion project.

Day said he could go on talking for hours about the technology HEA uses to capture exhaust heat from its gas-powered generation turbine, convert it to steam and then to electricity for area consumers.

And, he did just that — along with several other tour guides — for about 100 area residents Wednesday as the utility gave tours of its newly constructed, nearly operational facility that will generate the lion’s share of electricity for the area.

“I have to pinch myself walking around here because this was just an idea at one point,” Day said with a smile.

For several years HEA has been preparing to sever a decades-old power supply agreement with Chugach Electric Association at the end of this year. Since the early 1960s, HEA has purchased most of the power local consumers require — usually 58 megawatts with peaks at about 80 megawatts — from the Anchorage-based utility.

From 2014 on, HEA will rely on two pieces of infrastructure being completed this year to continue generation — the Nikiski Combined Cycle Conversion project and the Soldotna Combustion Turbine Plant. It will also have the Bernice Lake power plant purchased from Chugach in 2011 and its 11 megawatt share of power produced at the state-owned Bradley Lake hydroelectric facility in its portfolio as well. All told, the project — labeled Independent Light — will cost about $180 million.

The Nikiski project will come online within a month, HEA spokesman Joe Gallagher said.

The plant will be able to produce up to 18 more megawatts of power without any additional natural gas. The facility already produces 40 megawatts and would require additional gas to gain the maximum output of 80 megawatts with the steam power.

Looking around, one could easily get lost in plethora of pipes and wealth of machinery on display at the new facility, but despite the complex workings and new technology, the steam cycle idea is centuries old, Day said.

“This is old-school science,” Day said during a tour with a Clarion reporter, photographer and two other residents. “... You get an old physics book from that time and they’ll talk about this process. But big improvements in manufacturing, computer-aided design, the pumps are so much better, the drives are so much better, the valves, the controls, the computer operation of these things, have all helped.”

Previously, HEA had a three-way agreement with Chugach and Agrium, the remnants of which remain next to HEA’s new facility. When HEA moved its turbine from Sterling to Nikiski in 2001, it sold the steam to Agrium for their processes while Chugach provided the gas, Day said.

“For the gas, (Chugach) got the electricity and we got to sell the steam for a profit,” he said. “That was a good deal for HEA.”

Then Agrium closed in 2007 and HEA didn’t have anywhere to sell its exhaust heat, Day said. Since then, the utility had to just release it.

“It was just a waste, but it took us all these many years to get this equipment into place and get it all done,” Day said.

HEA also had to construct infrastructure to make up for services Agrium used to provide, like water, sewer and fire suppression.

“Agrium was a great partner. We’re sorry to see them go, but life goes on,” Day said.

Agrium crews also used to run the steam cycle while HEA crews ran the combustion turbine, but now a crew of five shift supervisors, 12 operators and a plant manager will operate both facets of the operation. HEA also had to expand its building and control room onsite to house all the operations.

“There are things you have to manage and control all the time,” Day said. “Remote operation of a steam plant is pretty rare. So we had to go to a 24/7 operation, which requires a number of shifts.”

Day said the turbine HEA uses at Nikiski is a 1985 design, but has relatively low mileage for a machine its age.

“A motorcycle guy would call it a garage queen,” he said.

The exhaust heat the turbine produces is about 975 degrees. After going through the heat recovery steam generator, its temperature is reduced to less than 400 degrees.

“It’s very similar to what you see on the wing of an airplane,” Day said of the gas turbine. “It compresses air, puts fuel into that compressed air mixture, ignites it, and then that expanding gas pushes a wheel that turns the turbine that is coupled with the generator and the gear box, which generates the electricity that goes out onto the system.”

The exhaust heat then produces steam, which is sent through a maze of piping in a separate building that generates more electricity and recycles the majority of the water — only about 5 gallons per minute are lost during process that cycles through 400,000 pounds of steam per hour.

“It’s pumping thermal energy from over there, turning it into mechanical energy, which we then turn into electrical energy that goes out on the grid,” Day said.

Day said it is a lot of complex machinery, but it is needed to produce efficiency.

“You have to have all this to squeeze the rind to get all the energy you can out of it,” he said.

Brian Smith is the city editor and a reporter for the Peninsula Clarion.

 

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