Separated from the U.S. mainland’s electric supply by an ocean, Hawaii is working toward a goal mandated by Hawaii’s Renewable Portfolio Standard (RPS), which requires 40 percent of the state’s electricity to be derived from clean-energy sources by 2030.
One of Hawaii’s strategies for achieving this goal is the construction of biomass facilities. Biomass is organic matter—made of living organisms, such as wood from various sources, agricultural residues, and animal and human waste—which can be converted into electricity. As of 2011, the state of Hawaii executed a 1,000-acre, 22-year license of biomass production lands.
American Electric Co. LLC is a locally owned Hawaiian company founded in 1946 and one of the largest contractors in the state. It has garnered multiple contracts for construction of biomass facilities. One is a $73 million, state-of-the-art, 7.5-megawatt (MW) biomass-to-energy facility near Koloa, Kauai, that will be in service in spring 2015 and produce electricity by burning wood chips from trees grown on that island. A second project was a $302 million expansion of the 1990 Covanta Honolulu plant in Kapolei on Oahu. It was completed in 2013 and added 32 MW of energy to the 90-MW facility.
Koloa, Kauai, biomass-to-energy facility
In July 2013, fossil fuels produced more than 80 percent of the energy on the island of Kauai. It is costly for Kauai residents, who pay approximately 42 cents per kilowatt, while mainland residents pay only single-digit fees.
Kauai has embraced biomass. The power authority, Kauai Island Utility Cooperative (KIUC), presented a request for proposals in December 2005. The Green Energy Team was founded on Kauai that year with the intention of developing a biomass-to-energy project. Subsequently, the Green Energy Team was awarded the project in March 2006 as well as a power purchase agreement (PPA) in March 2007, which was updated in 2011. According to a presentation by the Green Energy Team, “Unlike other islands of the world, Kaua’i does not have mainland or inter-island back-up energy feeds. Without inter-island or mainland back-up cable energy feeds, KIUC cannot simply select wind or photovoltaic. KIUC / Kaua’i must have ‘base load,’ ۲۴/۷ energy production components.”
“This will be the first closed-loop, biomass-to-energy plant in the United States, relying completely on the supply of its own sources of Kauai biomass wood chips, with no off-island dependence and completely renewable,” said Eric Knutzen, co-founder of the Green Energy Team, which owns the plant. “We are truly sustainable, producing power by Kauaians, on Kauai for Kauaians, as opposed to fossil-fuel energy sources that send money off-island.”
To provide fuel for the 7.5-MW (net output at grid connection) Kauai facility, existing and invasive Albizia trees are being harvested. In their place, trees such as eucalyptus, which have been approved by the state’s Department of Land and Natural Resources, have been planted and are being harvested. When the plant opens, the trees will be processed into wood chips, which will be burned to generate electricity. Kauai will essentially be growing the source for its future electricity production.
The Kauai biomass plant is a standard one, yet it is complicated in its structure and process. It was designed by the Standardkessel Baumgarte Group in Germany, an international producer of high-efficiency boiler technology and an equity partner in the project.
When the plant opens, the process of transforming the biomass during normal operation will begin in a fuel-storage building where the wood chips are stored. Through an automated control system, an overhead crane inside that building will pick up the wood chips and drop them into a hopper. From there, the wood chips will be transferred onto conveyor belts and transported to a boiler building where they will be dropped into a pusher-type grate firing system and burned. The fire will heat the water inside the boiler tubes to produce steam, which will spin a turbine to generate electricity. The electricity will then move from the turbine generator to the switchgear and then to a new substation on the Kauai plant. The plant will be later owned and operated by KIUC and will transport the power to their grid.
“The project began in January 2013 with the installation of the cable-tray system throughout the plant, which had been constructed in the months prior by Bodell Construction Co., the general contractor,” said Tim O’Reilly, senior project manager, American Electric LLC, the electrical contractor that presented a proposal to Standardkessel, finalized the contract in December 2013 and began work. “We pulled power and control cables through a 4,500-foot cable tray and made all the associated terminations for those cables to power all the different motors within the plant. One challenge was that the plant was designed by a German company, so all the drawings are in metric instead of in American measurements.”
Safety during construction was a major concern, especially as American Electric’s crew mounted cable trays to different steel supports within the boiler structure and the fuel-storage building and then across the conveyer belts. The crew of 16 electricians from the International Brotherhood of Electrical Workers Local No. 1186 had to work from lifts up to 20–۳۰ feet in the air or off of building scaffolding due to the elevations of some of the mounted cable trays.
“We were working at high elevations due to the size of some of the structures,” O’Reilly said. “In some cases, it is necessary to take the cable tray to the height of the crane. Depending on the degree of difficulty, the cable can be pulled by hand, but, in some cases, we used a cable-pulling machine. For a 90-degree bend in the tray, we didn’t want to have a guy standing there and physically doing it. We put a pulley in locations like that to pull the cable through that area. The trays were open at the top during that process and closed after the cables were pulled through. Then, we took the pulley out and moved it to a different location.”
Weather was a factor as well.
“When it rained hard over here, it got pretty muddy,” he said. We found work in different areas of the plant since we couldn’t work outside.”
After the crew pulled the cables through the cable trays, workers installed conduits connecting to the different equipment of the boiler, pumps, fans, steam turbine, generator, condenser, cooling tower, exhaust, emissions controls and automated system controls. That will be followed by terminations at the actual loads and at the main switchgear associated with the motors and the controls.
“We look at all the motors or control devices that we have to feed to a particular structure or area and make sure we have all our cables in so that we can pull all those cables at one time,” O’Reilly said. “Once we start energizing different loads within the plant, we will have the issue of the piping becoming excessively hot. We have to make the crew aware of the hot equipment so they won’t lean up against it. When we are under startup, we also have to take into consideration a lot of lockout, tagout procedures from both a mechanical standpoint and an electrical standpoint.”
Power generated at the Kauai facility is being sold to KIUC under a PPA approved by the Hawaii Public Utilities Commission in October 2011. When finished, the biomass-to-energy facility will contribute approximately 12.4 percent of total Kauai energy, helping KIUC reach its goal of 50 percent renewable-energy generation by 2023, a move toward Hawaii’s RPS mandate.
Covanta Honolulu at Kapolei facility
American Electric was also the electrical contractor on the 2009–۲۰۱۲, $۳۰۲ million expansion of Covanta Honolulu in Kapolei.
Covanta Energy was the designer, builder and operator of the facility, known as Honolulu Program of Waste Energy Recovery (HPOWER), owned by the city and county of Honolulu, which began commercial operation in May 1990. It processes municipal solid waste and scraps from paper trash to create electricity and serve the municipal waste-disposal needs of Oahu’s 850,000-plus residents and its millions of yearly visitors. Parsons Corp. was the general contractor.
“The result of the expansion is that the city and county of Honolulu was able to shut down a landfill,” O’Reilly said. “Now all of the trash on the island of Oahu is processed through HPOWER. The burning of trash creates steam and the plant makes electricity for the local power company. Technology has come a long way as far as waste management and trash burning. The challenge in working on the Kapolei facility project was that we were working around an existing plant. Trash trucks were coming and going, dropping off their loads. Buildings that had to be constructed for the expansion were spread out so as to fit in certain locations. The job was spread out over a large industrial complex. The cooling tower was set up in the back of the construction site, the turbine generator was in the middle and the boiler was set up on the front side. Because of that, we had some long cable pulls.
“We had a lot of issues related to pulling approximately 800,000 linear feet of cable since the electrical crews were in different buildings and different locations. We managed it by setting up a crew per building or per area with different foremen in each building. Cable trays that we installed went from building to building and the cable pull went from one building to another. Crews picked it up as it came to their area. We wanted to make manageable sections of work,” O’Reilly said.
As a result of the expansion by 32 MW, the facility now processes up to 3,000 tons per day of municipal solid waste, generating up to 90 MW of energy for Hawaiian Electric Co., which calculates to 8 percent of Oahu’s power needs. American Electric started work in March 2010 with a crew of 75 electricians and finished in January 2013, though the expansion was functional by June 2012.
Because of companies such as American Electric, it seems Hawaii is on its way to achieving the state’s RPS goal.