Some 150 tradesmen have converged on a "postage stamp-size site" in Anchorage to construct what its owner promises will be one of the most energy-efficient thermal generation powerplants in the world.
While most projects of the magnitude of Anchorage Municipal Light & Power's (ML&P) $275-million, 120-MW George M. Sullivan Plant expansion rise on sites of 10 acres or larger, crews are rubbing shoulders on a three-and-a-half-acre site, selected for its proximity to Anchorage Water and Wastewater Utility's (AWWU) municipal water supply, which is less than a mile away. Co-location of the two will achieve significant efficiencies as Sullivan captures residual heat from the plant's combined-cycle, natural gas-fired power generator and funnels it to AWWU facilities to heat water for Anchorage residents.
"In addition to supplying highly efficient power to Anchorage residents, we're capturing waste heat to warm temperatures by up to 15.2 degrees for 56,000 AWWU customers," says Jim Trent, general manager with ML&P.
The facility also will generate cleaner energy due to a 97% reduction in nitrogen oxide emissions, 80% lower carbon monoxide emissions and a 30% decrease in carbon dioxide, primarily due to enhancements to the plant's two aero-derivative 50-MW GE LM600 PF5 Sprint combustion turbine generators (CTG).
As planned, each CTG, equipped with a once-through steam generator, will feed a steam turbine generator producing another 20 MW of power. The configuration will require 15% less gas—saving more than $13 million annually—once the plant is up and running.
The two-year project, begun in April 2014, required 10 years of planning and negotiations, during which issues ranging from aging infrastructure, proximity to a steady supply of inexpensive gas and the desire to both minimize power disruption and reduce emissions all carried the day against some skeptics in city government, says Trent.
Nevertheless, the project has amounted to a mammoth undertaking for the modest-size utility, says Eugene Ori, ML&P's project sponsor. "We're not a Duke Energy; we're a 250-employee organization," Ori says, elaborating that a lack of in-house resources prompted the utility to consult with Portland, Ore.-based IEC Corp., a firm known for its work with smaller municipal utilities on the West Coast.
"They've been embedded with us from Day 1, collaborating on development of project scope, specifications and contract methodology," he says.
Prior to selecting additional team members, ML&P cleared and leveled the hilly site, removing thousands of pounds of rock and soil to ensure the utility wouldn't encounter geotechnical issues once work was underway. "The objective was to reduce our risk as thoroughly as possible prior to soliciting a request for proposals for engineering, procurement and construction (EPC)," Ori says.
To further reduce risk, ML&P's EPC solicitations not only required performance guarantees for power, heating and emissions reductions but the ability of candidates to self-perform 100% of work. "Because we only had one bite at the apple with the city, we didn't want to shuffle multiple contracts through city council," Ori says.