Alternative fuels, for both transportation and power generation, are an important component of Hawai‘i’s efforts to reduce its dependence on imported petroleum. HNEI conducts research, testing, and evaluation, to support the development of alternative fuels including biomass and biofuels, hydrogen, solar fuels, and methane hydrates. HNEI also conducts analysis and planning to assess the potential for the use of alternative fuels to meet Hawai‘i energy needs.
In support of the Hawai‘i Clean Energy Initiative, HNEI continues to conduct a wide range of assessments for the advancement of research, development, testing and evaluation of various alternative fuels. These alternatives include biomass, biofuels, hydrogen, and liquefied natural gas.
Biomass & Biofuels
Energy from biomass has, historically, been a significant part of Hawai‘i’s energy mix. With the decline of the sugar industry and aggressive State goals to reduce fossil fuel usage, there has been considerable effort in the state to identify new, cost effective means to produce biofuels and/or energy from biomass. Biofuels and bioenergy products require development of a value chain that includes production of the biomass resource, resource collection logistics, conversion technology(s), product distribution, and end use. While HNEI works with partners inside and outside the University to inform and enable development of the entire value chain, HNEI’s activities are focused primarily on the development of cost-effective conversion technologies and management of various technical and resource assessments. Ongoing work includes research on biocarbons, gasification technology, anaerobic digestion and bio-oil extraction, and the development of bioplastics and other high value products from waste streams. These activities support efforts to improve energy, food, and water security for Hawai‘i and the U.S.
Biomass and Fuel Processing
Biomass from agricultural, silvicultural, and urban sources can be used as the starting material to produce electricity, fuels, and higher value products. Since chemical and fuel properties of these materials can vary significantly, processing (such as biomass fractionation and thermochemical conversion of biomass) can serve to reduce variability and improve properties for a targeted end use application. Research in gasification focuses on producing liquid fuels from synthesis gas. This spans the spectrum of biomass energy conversion including pretreatment, conversion processes, and downstream processing.
HNEI has conducted research to develop cost-effective high rate anaerobic-aerobic digestion (HRAD) reactors that treat low to high strength wastewater within integrated modular platforms that can be shipped in cargo containers and installed on-site. The modular units can be mixed together in ways to accommodate anaerobic, anaerobic-aerobic, or aerobic digestion. They can also be installed in non-permanent cement structures that supported de-installation and removal of the structures if desired. The modular reactor design uses immobilized biochar media to support highly effective biofilms of methanogenic microbial communities under anaerobic conditions and activated biofilms under aerobic conditions. The reactor design has evolved from years of laboratory research and demonstration scale trials in industry. Currently, HNEI is seeking partners to deploy the reactors at scale.
HNEI is developing a new technology to produce liquid fuels from synthesis gas (syngas). The technology includes: (a) a patented bioreactor for high efficiency gas capture and conversion into polyhydroxybutyrate (PHB) by an autotrophic bacterium, and (b) catalytic reforming of PHB on a solid acid catalyst into hydrocarbon oil for drop-in liquid fuels.
Researchers in the Bioprocessing Lab are also developing a novel biorefinery process in which lignite-grade solid fuel (hydrochar) and bioplastics (polyhydroxyalkanoates, PHAs) are produced from cellulosic biomass. The hydrochar contains 40% more heating value than raw biomass and exhibits the same combustion performance of lignite coal. Hydrochar is a carbon-neutral solid fuel for co-firing of power plants. The PHA bioplastics are completely biodegradable and environmentally friendly to replace petrochemical plastics such as polyethylene and polypropylene in a circular economy. Because of the high value of bioplastics, the biorefinery increases the value of raw biomass by more than five folds.
Development of hydrogen transportation systems requires cost effective hydrogen infrastructure to produce, compress, store, deliver, and dispense hydrogen to hydrogen vehicles. The ultimate objective for introducing hydrogen in the transportation sector is to reduce the cost of hydrogen dispensed at the nozzle. In order to displace fossil fuels, hydrogen must be economically competitive with other transportation fueling options. Light-duty vehicles such as cars have largely been designed to use high pressure (700 bar – 10,000 psi) onboard hydrogen storage systems while heavy-duty vehicles such as buses, use lower pressure (350 bar – 5,000 psi) storage systems. HNEI has been working on several major projects that address these infrastructure challenges.
The objective of this research is to improve the durability and conversion efficiency of novel thin-film photo-absorbers for the photoelectrochemical (PEC) production of hydrogen. In this program, the HNEI’s Thin Films Laboratory is combining theoretical modeling with state-of-the-art materials synthesis and advanced characterization capabilities to provide a deeper understanding of PEC materials and engineer high-performance devices.
Since 2002, HNEI has conducted research to understand the formation and decomposition of methane hydrates for use as a fuel and to explore engineering applications of hydrates. Methane hydrates, comprised of a crystalline water lattice stabilized by the presence of methane are found in deep ocean sediments and arctic permafrost. Estimates of the amount of methane gas contained in hydrate deposits indicate an energy content exceeding that of all known hydrocarbon fuel resources.