Coal, Gas

Southcentral Power Project: Efficiency in Central Anchorage

Issue 3 and Volume 118.

By Justin Martino, associate editor

The Southcentral Power Project may technically be an expansion of an existing power plant, but the facility – a 200-MW, natural gas-fired power plant located in Anchorage – stands apart from many others because of its efficiency and how it was designed to operate in a difficult climate.

Chugach Electric Association, which owns 70 percent of the plant, and Municipal Light and Power, which owns the remaining 30 percent, focused on fuel efficiency when building the $359 million facility – an all-inclusive number that includes owners’ costs. Alaska produces more than half its power from natural gas, and insufficient pipeline capacity can be problematic even in a state with a large amount of natural gas resources.

The participation of these two utilities resulted in economies of scale intended to maximize savings over the life of the plant. The end result is a power plant that has given the fuel savings anticipated by the company and proved to be a better investment than upgrading an existing plant, according to Chugach Electric Association Senior Vice President of Power Supply Paul Risse.

Chugach Electric.
Chugach Electric.
The 200-MW Southcentral Power Project is the newest and most efficient power plant in Alaska. Photo courtesy of Chugach Electric.

Building a new plant

Risse said Chugach began looking at the possibility of building a new plant in Anchorage when the steam unit at Beluga Power Plant, located on the west side of Cook Inlet near Tyonek, approached the 30-year-old mark. In addition to being older, the Beluga facility is not road accessible, and it was necessary to fly to reach the facility and move large equipment by barge once or twice per year.

“We did a number of assessments on work we might have to do to extend its life for a notable period of time – 20 years, approximately – and the investments required to do so, and we weighed those against building a newer plant in town,” Risse said. “When we weighed those costs and efficiency improvements, a new plant was a better decision.”

The decision was helped by the timing – the project began around the time the U.S. economy took a turn for the worse, which helped the cooperative get better terms from contractors than it might have otherwise, Risse said. That led to the decision to use an engineering, procurement and construction (EPC) contract to integrate more of the work. The utility purchased the major equipment, such as the gas turbine, the steam turbine and the boilers, itself.

The official groundbreaking for the plant was in March 2011, and construction was finished in 22 months – five months ahead of its original anticipated schedule, Risse said. The plant was also completed under the estimated budget.

Building the plant required planning, Risse said. Large modules used in the plant were barged to the Port of Anchorage and transported on special trailers on the road. Transporting the gas turbine across the continental U.S. and dealing with changes in rules in different states also posed a challenge. Heavy OTSG modules weighing more than 300,000 pounds posed the most significant transportation challenge.

“It all made it here in a timely manner,” he said. “Alaska just means it takes longer. Mostly it’s coordination and a lot of planning.”

In the plant’s first year of operations, the SPP exceeded its projected savings. Before Chugach took control of the plant on February 1, 2013, it was estimated the new plant would save the cooperative’s members more than $15 million in avoided fuel purchases in its first year. Though November of 2013, however, the savings had already added up to $21.7 million.

Chugach Electric.
Because of the weather in Alaska, many modules that are typically left outdoors had to be placed in buildings, which added to the cost of the project. Photo courtesy of Chugach Electric.

Inside the plant

The plant is the most efficient in Alaska, as well as the third-largest in the state. Parsons Brinkerhoff served as the owners’ engineering firm for the plant and assisted Chugach in the bidding process, while the EPC contract was awarded to SNC-Lavalin.

The plant is equipped with three GE LM6000PF turbines from General Electric, rated at 48 MW each. The turbines were chosen for both their efficiency and their fast start capability that allows them to reach full capacity in just 10 minutes. The plants 57.5-MW steam turbine was furnished by Mitsubishi Power Systems America. Once through steam generators were purchased from Innovative Steam Technologies, a choice which prevented the need to install bypass stacks at the plant for simple cycle operation. These units can be duct fired to create a total plant capacity of 200MW.

When building the plant, Risse said the cooperative looked at more than 400 “lessons learned” from other projects.

“We went to a lot of other projects during the preliminary design phase to identify things we wanted to do, and that played out very well,” he said. “Many of those things were integrated into the planning and the project as it stands today.”

One of the major challenges facing the plant was the weather in Anchorage, which has a long winter with a great deal of snow and ice accumulation. The buildup of snow can bury parts of the power plant that would normally be left outdoors and make maintenance more difficult, leading to the decision to place those parts inside the building to protect them from the conditions, Risse said.

The building is also located in the middle of Anchorage, and Chugach worked with the community to ensure the plant was built with the minimum amount of problems.

“As part of the construction, we reached out at multiple community meetings,” Risse said. “We would attend and explain what we were doing. One notable advantage for this site is it was purchased in the early ’60s, and a power plant had been here since the mid-’60s. A lot of people didn’t even know that.”

The efficiency of the plant’s design is likely to keep it no more noticeble than the plant already on site. The technology used reduces carbon dioxide by 25 percent and carbon monoxide and nitrous oxide by 95 percent. In addition, Risse said the plant is exceptionally quiet.

Final results

Ahead of schedule, under budget and with savings even greater than anticipated, the Southcentral Power Project has been a benefit for its owners and is another example in the highly-efficient combined cycle natural gas-fired power plants that are becoming increasingly important in the U.S. power generation industry.

“It’s working out great for us,” Risse said. “The decision to build a new plant has certainly been validated.”

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