(click image to enlarge) The Solar Mercury 50 natural gas-fired turbine will operate throughout the summer in Lamar. ARPA purchased the turbine, but the Lamar Utilities Board is operating it. The turbine can be easily controlled by computer.

ARPA tests turbine to help ensure adequate power supply

The Arkansas River Power Authority in southeastern Colorado was looking for cutting-edge turbine technology to help ensure system reliability in these uncertain times.

The 4.2-megawatt Solar Mercury 50 turbine seemed to fit these requirements. "We were impressed with it," explained ARPA General Manager Jim Henderson. "We thought it would be a move toward future generation with improved efficiencies. And it's small enough for us to afford."

While ARPA bought the turbine, the Lamar Utilities Board operates it. It's located next to Lamar's natural gas-fired powerplant.

"Lamar has a history of generating with natural gas," Henderson explained. "It seemed like a natural fit." It also placed the turbine near an existing natural gas supply and the grid that serve the cities of Lamar, Las Animas, and Holly.

Close to load

"Given the problems the power grid has experienced, it's wise to have generation as close to the load as possible," Henderson explained. "When the grid gets into trouble, part of our power supply could be taken away from us. It's important for us to be able to meet our own load."

The turbine is one way of achieving that goal. It offered several advantages that attracted ARPA's attention.

"It's designed to be operated remotely," said Henderson. "The controllers can start it with the click of a mouse, from any location. It comes up to full capacity in less than 10 minutes. To have a unit that nimble is very important, especially when we're trying to use it as a 'peaker.' "

Efficient operation

Henderson was also impressed with its efficiency. "It's at least 20 percent more efficient than the steam unit at Lamar, so it burns less natural gas," he explained. "When you're standing beside the turbine, it's hard to tell whether it's running or not. It operates cleanly and quietly."

These environmentally friendly aspects of the turbine appealed to ARPA. In addition, as natural gas prices have risen, efficient operation is a big advantage. That leads to significant savings on fuel costs.

ARPA commissioned the Mercury 50 on March 1, and it underwent tests before being placed into service on April 16. While it's only been a short time, Henderson said it has operated with lower heat rates than anticipated, so it's been even more efficient than expected.

The turbine is also designed to be efficient when it's running at less than full load. Since it's being used as peak generation, that's important. The system doesn't have to run at capacity to operate efficiently. But its versatility means that it's also capable of running as a base load unit.

The ARPA unit is one of seven or eight test units around the country. The Mercury 50 is not yet available commercially. ARPA and the Lamar Utilities Board will continue testing the system this summer.

During the testing, the Mercury 50's operation will be compared to two diesel engines. The testing will give the Arkansas River Power Authority information to develop a guidance document for small- to medium-sized municipal electric utilities interested in purchasing new generation.

Factors to be compared include capital equipment costs, cost and ease of installation, fuel efficiency, operational capability and costs, environmental impacts, and reliability. If this one operates well, ARPA may buy additional turbine units. There is room for two more units in Lamar. However, "we really can't tell yet how the price of natural gas will affect our plans," Henderson said.

"It's a beautiful little machine," he added.