Biomass is organic matter in the form of plants, farming or forestry waste and the organic part of municipal and industrial waste.
In Hawaii, biomass for electricity can include sugar cane bagasse (the fibrous residue left after sugar is extracted), forest products and garbage. For decades sugar plantations on all islands in Hawaii burned sugar cane bagasse to create process heat and electricity for their own use and sold the excess to the utility on their island. This now only provided a high level of renewable electricity to Hawaii but helped extend the viability of the sugar industry by giving the plantations another income stream.
At some times in the past as much as half the electricity on the smaller Hawaiian Islands was supplied in this way. However, biomass power has declined as sugar mills have shut down and today the only working plantation is on Maui Island.
Biomass can be used as fuel to generate heat for steam that can either be used directly as “process heat” (for example, for a commercial laundry) or to turn a turbine to produce electricity.
In biomass gasification, the biomass feedstock is converted to a fuel gas and used in a gas turbine to generate electricity. This technology is currently in the demonstration stage.
With landfill gas, the anaerobic (i.e., lack of oxygen) decomposition of refuse creates a gas that is collected and directed to a gas turbine to produce electricity. In the past, landfill-generated methane gas provided electricity from Kailua’s Kapaa Quarry on Oahu. The plant was closed after a major equipment failure, but some developers have shown interest in providing landfill-gas power again.
Hawaiian Electric Company purchases power from the 46-MW H-POWER refuse-to-energy plant. The plant is in the process of expanding to add a third boiler and another turbine which should increase its capacity to about 73 MW. Hawaiian Electric and H-POWER are negotiating a power purchase agreement which will need approval of the Hawaii Public Utilities Commission.
Maui Electric Company continues to purchase power from the HC&S Puunene Sugar Mill which uses sugar cane bagasse to provide up to 16 MW of renewable energy.
Honua, an Oahu-based company, has signed a power purchase agreement with Hawaiian Electric Company that has been approved by the Hawaii Public Utilities Commission. The company plans to generate approximately 6 MW of electricity from construction and other waste in a plant in Campbell Industrial Park.
Hu Honua, a company on Hawaii Island, plans to build a 22MW plant that would use existing eucalyptus tree forests to create renewable energy.