The biofuel process they are doing in Ka‘u results in pyrolysis oil. There are safety and other concerns associated with this oil.
It surprises me that HECO was willing to rush this process, after having ignored geothermal for years.
The National Renewable Energy Laboratory, a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, published a technical report on pyrolysis oil:
Large-Scale Pyrolysis Oil Production: A Technology Assessment and Economic Analysis
M. Ringer, V. Putsche, and J. Scahill
Pyrolysis is one of a number of possible paths for converting biomass to higher value products. As such, this technology can play a role in a biorefinery model to expand the suite of product options available from biomass. The intent of this report is to provide the reader with a broad perspective of pyrolysis technology as it relates to converting biomass substrates to a liquid “biooil” product, and a detailed technical and economic assessment of a fast pyrolysis plant producing 16 tonne/day of bio-oil. Read more
Here is some information from that report. (The bold and underlining is my emphasis.)
3. Properties of Bio-oil
The properties of bio-oil can encompass a broad range of parameters because of the complex nature of this material. Even if one is able to perfectly reproduce all of the processing conditions necessary to produce bio-oil, the biomass feed, itself, can influence the nature of the final product. Not only are there differences between types of biomass species but also where a particular species is grown can affect things such as the composition of mineral matter present. Given this non-uniformity in the starting material and the high temperature reactive environment to which the prompt biomass vapor fragments are exposed during pyrolysis, it is not unusual to see variations in many of the physio-chemical properties of bio-oil. For some applications, the small variations will be of little consequence, but in situations where it is desirable to use bio-oil in devices that have been designed to operate on hydrocarbon fuels, some of these properties will make operation difficult or simply not feasible.
3.4 Environmental / Health
Given the large number of compounds in bio-oil, it obviously raises concerns about the human health and environmental effects of this material. As reported earlier in this document, more than 300 specific compounds have been identified in biomass pyrolysis oil and some of those compounds are known carcinogens such as benzene and phenanthrene. In addition there are many compounds in bio-oil that have not been identified and their toxicity or health effects are not known by the research community developing biomass fast pyrolysis technologies.
Click to watch a video with background of the microfuel “biomass to fuel” technology.