Second Generation Biofuel
Why use biofuels?
Extracting and burning fossil fuels increases the amount of CO2 in the atmosphere. Biofuels are the only fuel type where the source (a plant) absorbs CO2 from the atmosphere, helping to offset the emissions produced when they are consumed.
Second generation biofuels
Many people are familiar with "first generation" biofuels such as ethanol and biodiesel, which are primarily derived from corn and soybeans at present. Yet corn and soybeans are staple food crops and require large amounts of land and resources such as water and fertilisers. This makes them unsustainable sources for biofuel.
Sustainability considers environmental, economic and social impacts. In addition to having lower lifecycle CO2 emissions, sustainable second-generation biofuels do not compete with food or fresh water resources or cause deforestation, while providing socioeconomic value to local communities.
Jatropha
Close up of jatropha seed pods
Jatropha is a plant that grows to approximately three metres high and produces seeds that contain inedible lipid oil that is used to produce fuel. Each seed produces between 30 and 40 percent of its mass in oil and jatropha can be grown in a range of difficult conditions, including arid and otherwise non-arable areas, leaving prime areas available for food crops.
Non-negotiable criteria
Jatropha growers Tanzania
The partners have been non-negotiable about the three criteria any environmentally sustainable fuel must meet for the test flight programme. These are social, technical and commercial.
Firstly, the fuel source must be environmentally sustainable and not compete with existing food resources. Secondly, the fuel must be a drop-in replacement for traditional jet fuel and technically be at least as good as the product used today. Finally, it should be cost competitive with existing fuel supplies and be readily available.
The criteria for sourcing the jatropha oil required that the land was neither forest land nor virgin grassland within the previous two decades. The quality of the soil and climate is such that the land is not suitable for the vast majority of food crops. Furthermore, the farms are rain-fed and not mechanically irrigated.
The test flight partners engaged Terasol Energy, a leader in sustainable jatropha development projects, to independently source and certify that the jatropha-based fuel for the flight met all sustainability criteria.
Once received from Terasol Energy, the jatropha oil was refined through a collaborative effort between Air New Zealand, Boeing and leading refining technology developer UOP, utilising UOP technology to produce jet fuel from renewable sources that can serve as a direct replacement to traditional petroleum-based fuel.
Fuel processing
UOP fuel processing equipment
UOP processed biological feedstocks converting them to green jet fuel.
The process uses hydrogen to remove oxygen from natural oils and then further refines the deoxygenated oil to produce the synthetic paraffinic kerosene (SPK) or jet fuel. This process is similar to the hydroprocessing technology used in refineries today to produce petroleum-based fuels.
This is the largest sample made to date of green jet fuel made from second generation resources.
Fuel technical requirements
Laboratory testing of biofuel by Chris Lewis, Rolls-Royce fuel specialist
In order for sustainable biofuel to be a viable solution for aviation, they must have the same energy content and perform the same or better than today's aviation fuel, Jet-A1.
Sustainable aviation biofuels must also work in the existing aviation infrastructure - requiring no change to aircraft, engines or fuelling mechanisms. In addition, to be practical, sustainable aviation biofuel must be able to mix with Jet-A1 fuel so that airlines would be able to use the blends until production is fully ramped up.
The laboratory testing that Rolls-Royce carried out on the fuel showed the final blend has excellent properties meeting, and in many cases exceeding, the stringent technical requirements for fuels used in civil and defence aircraft. The blended fuel therefore meets the essential requirement of being a "drop-in" fuel, meaning its properties are virtually indistinguishable from conventional Jet-A1 fuel, which is used in commercial aviation today.
What will happen to the results of the biofuel test flight?
The results and data recorded during the Air New Zealand biofuel test flight will contribute towards the certification of the fuel for use in commercial aviation.
