Energy Resources In Maui
Oil Power Plants
The existing Kahului and Mā‘alaea plants
HECOʻs 2 main electric power plants on Maui island, with 38 MW and 212 MW of respective electric generating capacity.
Pros: provides readily available firm power.
Cons: the oil supply must be imported; these plants result in significant carbon dioxide emissions and conventional air pollution; the Kahului power plant must be retired in 2027-28 in order to comply with the expiration of the National Pollutant Discharge Elimination System permit related to the release of water used for cooling into the ocean and its location in a tsunami inundation zone; and 24% of the capacity of the Mā‘alaea plant (50 MW) will be retired by 2030 if not sooner, due to lack of spare parts for the diesel engines.
BioFuels
Assess the feasibility of biofuel as a firm energy source, considering land use, emissions, and sustainability.
Any biogenic resource that can be used for fuel, including firewood, charcoal, perennial grasses, food crops (and their residues) such as from corn, wheat, and sugarcane; and vegetable oils derived from sunflowers, soybeans, palm trees, and used cooking oils. Can be used to generate electricity. While most biofuels are solid or liquid, they can also be gaseous in the form of biomethane, also called Renewable Natural Gas (RNG), where biofuel is upgraded to a quality similar to natural gas through anaerobic digestion to produce a methane concentration of 90% or more. A 40 MW biofuel plant has been proposed for siting in central Maui by Ameresco Inc. (Kuʻiu Biofuels), which could use liquid or gaseous biofuels, including hydrogen or RNG.
Pros: the fuel supply is firm, potentially abundant and renewable, and cleaner than making energy from petroleum.
Cons: there are localized land use constraints on the potential supply; some biofuels may require a large amount of water; and the renewability, air pollution and carbon dioxide emissions are highly dependent on the growing practices, processing/manufacturing, transportation, and how the energy is produced (using lifecycle analysis). Procurement costs are higher for biofuels.
Distributed Photovoltaics (PV
Investigate the potential of small-scale distributed solar PV to reduce the need for new transmission lines.
The use of solar PV, with or without onsite battery energy storage, at individual homes and businesses.
Pros: There is more than enough cost-effective solar PV available to meet 100% of the electricity needs of Maui. State and federal tax credits can be taken by eligible taxpayers. Many homes with solar PV systems have been part of HECOʻs Net Energy Metering program that pays customers for selling surplus electricity back to the grid. Some solar energy companies are willing to install collectors on homes and businesses with no upfront payments. Utility customers such as renters who cannot put solar PV on their own roofs may be able to participate in the Shared Solar program of HECO. To the extent that homes and businesses become self-sufficient in electricity generation and use this reduces the need for power transmission lines.
Cons: There is a significant need for battery energy storage or utility-provided electricity on days and times when the Sun does not shine. Not everyone can afford solar PV systems.
Wind Farms
Generally refers to a group of horizontal axis wind turbines in the same area to produce electricity. Wind farms vary in size from a small number of turbines to several hundred.
Pros: a readily available source of renewable energy in windy areas, as long as sufficient land is available to site the turbines. Can be co-located with agricultural or grazing lands.
Cons: some people oppose them because of their visual impacts such as shadow flicker and noise, habitat loss. They may interfere with radar. Wind farms also kill a small number of birds and sometimes bats.
Vertical Axis Wind Turbines
Research the potential of vertical wind turbines & their applications in Hawaii.
Wind turbines that can utilize wind from any direction as the blades are mounted on top of the shaft rather than in front, and when they spin they rotate around it. However, there also are several vertical wind technologies that are bladeless and do not have moving parts and/or capture kinetic energy. The Maui County government is considering supporting the development of a demonstration project for at least 1 of its 6 wastewater treatment plants with the company Wind/Water/Power, using the patented Atmospheric Wind Extractor (AWE) constant power output technology.
Pros: simpler design; quieter than horizontal axis wind turbines; needs less space and has lower visual impact; insensitive to wind direction; works well with low wind speeds, as little as 2 mph; some technologies produce clean water as a byproduct; safer and less of a risk to birds and bats; more efficient in areas with variable wind patterns, such as urban environments with tall and obstructive buildings; easier and cheaper to maintain and service.
Cons: lower power production and much less scalability, and higher capital costs per kW. Can experience greater turbulence, reducing their performance and lifespan.
Wave Energy
Power produced by floating turbine platforms or buoys anchored to the ocean floor that rise and fall with the ocean swells.
Cons: there are no commercial projects as of yet in the U.S. Projects will need the approval of the U.S. Bureau of Ocean Energy Management (BOEM) and U.S. Department of Defense. Some fishermen and conservationists may object as the projects could have adverse effects on marine mammals (e.g. humpback whales) and fisheries. Wave energy projects have not proven to be cost effective and have not yet reached commercialization.
Firm Renewable Power
Renewable power sources that are available all the time, such as biofuels, geothermal, and hydro, that could replace the oil-powered generating plants after they are closed. Necessary to provide energy during periods of intermittency of solar and wind power production.
GeoThermal Energy
Natural heat from the Earth brought to the surface in the form of hot ground water or steam that can be used as fuel to generate electric power, in heat pumps, or used directly to heat swimming pools or for space heating.
Pros: can provide relatively clean and firm renewable power. Direct heating applications have minimal environmental impacts. Some tax credits are available.
Cons: results in hydrogen sulfide (H2S) emissions, a foul odor, and other site specific impacts such as water pollution and a small amount of hazardous wastes. Hawaii’s main experience with geothermal energy, at the Puna Geothermal Project on the Big Island, has been mixed with several lawsuits and opposition from the local community. A policy prohibiting geothermal development that adversely impacts Upcountry Maui communities or culturally sensitive resources was adopted as part of the Makawao-Pukalani-Kula Community Plan in 1996.
Utility Scale Solar
Utility-scale solar
Generally refers to solar PV farms with a large number of solar panels totaling 1 MW or more that are owned by a third party and sold into the utility grid as direct current (DC) electricity, though other options are possible e.g. concentrated solar power or solar thermal plants.
Pros: such projects are highly cost-effective on Maui, and do not produce air pollution or greenhouse gasses, nor do they use water.
Cons: there may be some public opposition to these projects if they are sited too close to residential communities or other conflicting land uses. Projects take an average of 5 acres of land per MW installed, creating a need for large areas of available land.
Offshore Wind
Investigate the feasibility of offshore wind for long-term renewable energy goals.
Floating wind turbines that would be placed in the Pacific Ocean more than 12 miles offshore from the Hawaiian islands. Such projects would be more likely located off of Oahu than Maui.
Cons: offshore wind power leasing and development in Hawaii is in its earliest stage in Hawaii (the only operational projects in the U.S. are off the East Coast). Projects will need approval from the U.S. Bureau of Ocean Energy Management and U.S. Department of Defense. Some fishermen may object. Community opposition to the various proposed projects has proven to be a challenge. Deep waters have also presented challenges for project siting.
Ocean Thermal Energy Conversion (OTEC)
Technology to tap the vertical temperature difference in the ocean between the relatively warm surface and cold depths (thermal gradient) to generate electricity with a heat engine that uses ammonia or another working fluid.
Pros: Hawai‘i is the best location in the U.S. to develop this renewable energy technology. Provides a reliable source of clean electricity. The technology has been tested off the Kona coast at the Natural Energy Laboratory by Makai Ocean Engineering since 2015.
Cons: the technology has proven difficult to scale up cost-effectively. Maintenance costs are high and the pipes could have harmful effects on marine life.
Virtual Power Plants (VPPS)
Virtual Power Plants (VPPs): Explore the effectiveness of virtual power plants (VPPs) and other demand-side management technologies to enhance grid resilience.
Local aggregations of distributed energy resources (DERs), typically rooftop PV systems with battery storage arrays, and sometimes electric vehicles (EVs) and chargers, which can help balance electricity demand and supply and provide utility-scale and utility-grade grid services like a traditional power plant.
Liquified Natural Gas (LNG)
Governor Josh Green proposed in 2024 that the State use LNG as a transition fuel; the Hawaii State Energy Office is studying the issue. Using LNG would require the import of natural gas that has been liquified, by cooling it down to cryogenic temperatures (-260°) at 1/600th of its volume in the gaseous state. Liquefaction is done to facilitate easier storage and transportation without pipelines, for eventual use elsewhere back in the gaseous form. Use of LNG in Hawaii would require a Floating Storage Regasification Unit (FSRU) on ships as long-haul LNG carriers instead of an LNG land terminal, as well as LNG barges. Hawaii Gas imports small amounts of LNG from California and in 2025 may also import from British Columbia, Canada. Pasha Hawaii operates three LNG-powered container ships out of the Ports of Long Beach, Oakland and Honolulu.
Microgrids
A small network of self contained electricity users with a local source of power supply that is usually attached to a centralized grid, but is able to function independently as distributed power production and consumption. The Public Utilities Commision of Hawaii has an open though inactive Microgrid Docket.
Energy Efficiency and Demand Side Management Grid Services
A large range of technologies and behaviors that can reduce electricity and energy consumption by end users, especially homes and businesses. These include heat pumps (for heating and cooling), heat pump water heaters, ceiling insulation, compact fluorescent and LED light bulbs, more efficient refrigerators, air conditioning units and other appliances. Another option is to voluntarily reduce electricity consumption during high demand periods of the electric utility. A variety of tax credits and rebates are available to promote these options among consumers.
Pros: a cost-effective and often rapid way to reduce electricity consumption. There is a robust energy efficiency rebate and education program in Hawaii through Hawaii Energy. Energy audits can also provide energy savings.
Cons: many consumers cannot afford these technologies and often lack adequate information on the options or where to buy them.
Renewable Natural Gas (RNG)
RNG, also called biomethane, is biogas that has been processed to purity standards. Biogas is produced from various biomass sources through a biochemical process, such as anaerobic digestion, or through thermochemical means, such as gasification. Biogas from landfills is also called landfill gas. There have been proposals to generate RNG from the Central Maui Landfill.
Pros: locally produced, could be generated right across the road from the Ku‘iu biofuel plant. It would reduce the amount of methane released from the landfill. Lower greenhouse gas (GHG) emissions on burning than LNG.
Cons: still considerable GHG emissions. May be more expensive than other renewable sources. May not provide large enough quantities to play a significant role.
Nuclear Fusion
An advanced nuclear technology whereby two light atomic nuclei combine to form a single heavier one while releasing massive amounts of energy. The reaction would take place in a state of matter called plasma — a hot, charged gas made of positive ions and free-moving electrons with unique properties distinct from solids, gasses or liquids. Most of the fusion reactor concepts under development would use a mixture of deuterium and tritium — hydrogen atoms that contain extra neutrons.
Pros: Fusion could generate four times more energy per kilogram of fuel than nuclear fission and nearly 4 million times more energy than burning oil or coal. Fusion fuel is very plentiful and easily accessible: deuterium can be extracted inexpensively from ocean water, and tritium can potentially be produced from the reaction of fusion-generated neutrons with naturally abundant lithium.
Cons: The technology is nowhere near commercial or cost-effective. Fusion reactors produce a small quantity of low- and medium-level radioactive waste materials, such as activated metals and concrete. An optimistic assessment is that a commercial fusion power plant could not be built and operating before 2050. In addition, the technology would be most practical in large facilities and thus impractical for Maui.
Advanced Small Modular Nuclear Fission Reactors (SMR)
Advanced nuclear power reactors with a capacity of 5 to 500 MW. Like any fission reactor, a SMR uses energy from a controlled nuclear chain reaction to create steam to power a turbine to produce electricity. While there are no operating SMRs in the U.S., a demonstration plant is being built near Kemmerer, Wyoming by TerraPower, a company founded by Bill Gates (who is also board chairman). Another SMR project planned for Utah was canceled in November 2023.
Pros: electricity generation from a SMR would likely be more affordable than conventional nuclear power plants operating in 28 states in the mainland U.S.; no air pollution and they are likely safe. Lifecycle greenhouse gas emissions are low, comparable to solar and wind power. These plants have a lower radioactive inventory per reactor than conventional nuclear power plants.
Cons: Article XI, Section 8 of the Hawaii State Constitution states “No nuclear fission power plant shall be constructed or radioactive material disposed of in the State without the prior approval by a two-thirds vote in each house of the legislature.” The radioactive waste disposal problem has not been solved. Nuclear power technology is controversial and a proposed nuclear reactor of any size in Maui would likely be met with significant public opposition.
Waste to Energy (Hpower)
A technology that processes garbage and burns it in furnaces to produce steam that drives a turbine generator. Often called refuse derived fuel (RDF). A facility has been operating since 1989 on Oahu at the Campbell Industrial Park in Kapolei by Covanta Honolulu Resource Recovery Venture (H-Power). H-Power burns 90% of the island’s municipal solid waste and sells 73 MW of its electricity to HECO, which is then distributed to its customers. The Hawaii State Energy Office and Office of Planning and Sustainable Development are developing a plan to consider a waste to energy facility on Maui and other Hawaiian islands.
Pros: could provide a form of potentially renewable biomass energy and help address Maui’s solid waste disposal requirements by reducing the need for landfilling of such wastes.
Cons: the H-Power facility has a quota of trash to be delivered from Honolulu, so there is an incentive to burn as much as possible and the company must be paid for any shortfalls. H-Power is a significant emitter of air pollution, such as nitrogen oxides, carbon monoxide, particulate matter, hydrochloric acid, mercury, among others. Since oil needs to be added to counteract the cooling effect of wet waste, there’s an expense to keep burners running, with carbon dioxide and other pollutants entering the air – thus, the H-Power plant is also a major emitter of greenhouse gasses.