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Making best use of Railbelt generation Chugach Electric official explains how the utilities dispatch power across the transmission grid to manage costs and reliability ALAN BAILEY Petroleum News
The question of how best to manage the dispatch of electrical power from power generation plants across Alaska’s Railbelt has long been a subject of debate, given the need to supply power to Railbelt consumers at reasonable cost and with an acceptable level of reliability. The Railbelt power system is unusual in that, while supporting a relatively small number of electricity consumers over a large geographic area, it is completely isolated from the interconnected power grid elsewhere in North America.
On Dec. 13, during Law Seminars International’s Alaska Energy Markets and Regulation conference, Mark Fouts, executive manager, fuel and corporate planning, for Chugach Electric Association, explained how the Railbelt utilities currently manage the use of the various Railbelt generation facilities, and what opportunities there may be for making the power supply system more cost-effective.
Base-load power Fouts distinguished between what he referred to as base-load facilities and reserve or peaking units. The base-load facilities provide the core, relatively stable power that is needed continuously, while the peaking units kick in to meet spikes in power demand. Reserve power is needed to ensure power supply continuity, should a generator go out of service for some reason. With the power from peaking units being expensive relative to that of the base-load systems, the general tactic is to minimize the use of peaking generation, Fouts explained.
Across the Railbelt there are seven base-load generators, Fouts said. Those include coal, diesel and naphtha fueled systems in Fairbanks, North Pole and Healy; a gas-fueled plant at Eklutna, north of Anchorage; the gas-fired Southcentral Power Project in Anchorage; and a gas-fired plant at Nikiski on the Kenai Peninsula. Municipal Light & Power is also bringing on line its new gas-fired Plant 2A in Anchorage. Together the base-load plants provide about 80 percent of the Railbelt power, with three hydroelectric plants near Eklutna Lake and at Cooper Lake and Bradley Lake on the Kenai Peninsula contributing about 15 percent of the power, Fouts said. There are also three wind farms connected to the grid.
Balancing areas There are six independent Railbelt electric utilities, each of which owns and operates some portion of the Railbelt power generation, transmission and distribution system. Consequently, the grid is divided into several areas, within each of which the electrical power supply is balanced across the continuously varying electricity load. Each day utility dispatchers plan how to handle the anticipated load on the following day, assessing what generation facilities are available and calling each other to figure out how best to use the most efficient generation resources, Fouts explained.
At the same time, as the actual load varies during the course of the day, generators ramp up and down automatically to follow the load. As this happens, each utility can typically meet 80 to 90 percent of its load using its own base-load generation capacity, while purchasing the remaining capacity from other utilities. Because all of the utilities are regulated by the Regulatory Commission of Alaska, the utilities know each others’ generation costs and can, therefore, determine how to reduce the cost of power through these inter-utility energy sales. Essentially, when one utility sells power to another, the two utilities split any resulting cost savings, so that both utilities can benefit financially from the use of an efficient power generation facility. Utilities also buy and sell spinning reserves, the reserve power needed to accommodate power generation outages, Fouts commented.
Joint dispatch But greater efficiencies could be achieved if utilities are able to merge their load-balancing areas, thus implementing a single power regulation system across the service areas of multiple utilities. Modeling of the Railbelt grid has indicated that savings of $10 million to $30 million per year in fuel costs could be achieved through a joint dispatch system across the grid, Fouts said. Those saving would presumably translate to reduced electricity bills for consumers. This type of joint dispatch arrangement could also result in improved certainty over fuel purchase commitments in take-or-pay fuel supply contracts, Fouts said.
Anchorage utilities Chugach Electric Association and Municipal Light & Power are in the process of merging their dispatch systems into a single balancing area, to make optimum use of their most efficient power generation facilities. Matanuska Electric Association has decided to join this arrangement, with the ultimate result of implementing a tightly coordinated power pool across Anchorage and the Matanuska-Susitna valleys. Other Railbelt utilities that are not part of this “tight pool” will be able to continue to sell and buy power to and from the pool. Extension of the joint dispatch arrangement across the entire Railbelt would require the coordination of generation and dispatch across the complete grid.
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