“Advanced biofuels’’ is a general term for biofuels that are not commercially available on the market today that are produced from new or improved technology, often using non-food feedstocks that can deliver better performance with respect to GHG balance, environmental impacts and compatibility with fueling infrastructure than current biofuels.
The IEA defines advanced biofuels as: “different emerging and novel conversion technologies that are currently in the research and development, pilot or demonstration phase. This definition differs from the one used for “advanced biofuels” in the US legislation, which is based on a minimum 50% life-cycle greenhouse gas (GHG) reduction and which, therefore, includes sugar cane ethanol” (IEA 2017).
The European Sustainable Transport Forum’s Sub Group on Advanced Biofuels opted for a simpler definition of “those produced from biomass other than food/feed crops while meeting the EU sustainability regime under the legislation in force.”
Within the proposed revision to the Renewables Fuels Directive (RED), advanced biofuels are those which are produced by those feedstocks identified within Annex IXA of the proposed regulation. The Sub Group of Advanced Biofuels within the EU Sustainable Transport Forum allows for a broader feedstock base. It identifies advanced biofuels as those produced from biomass (per the proposed RED definition of biomass which is broader than the feedstocks in Annex IX other than food/feed crops) which meet the EU sustainability regime.
Nevertheless, advanced biofuels is an imprecise name because the feedstock, technology and also the final biofuel produced (which could be ethanol, methanol, DME, Butanol, synthetic diesel, esterified oils [biodiesel], compressed or liquefied gas, even hydrogen derived from biomass, and others) can vary widely. In fact, the Sub Group of Advanced Biofuels refers to Advanced Renewable Fuels as advanced biofuels, and liquid and gaseous fuels proposed from renewable intermediates or renewable process by-products (H2, CO, CO2).
The main elements that are important in the definition of advanced biofuel are the technology, development stage, potential deployment (directly linked to the potential sustainable availability of the feedstock required) and the key performance indicators with respect to overall GHG mitigation, costs and other environmental impacts.
The environmental and social performance depends, however, on many factors and such performance indicators are not the main distinguishing factors between conventional and advanced biofuels.
The most important category of advanced biofuels in terms of future production volumes is that produced from lignocellulosic biomass. Different key technologies can convert lignocelluloses to ethanol via hydrolysis techniques, synfuels via gasification or to bio-oil via pyrolysis. Many process variations exist or can be used in combination and are at pilot or demonstration phase, or even beyond, but the key is the use of lignocellulose as feedstock.
Lignocellulosic feedstock is the most abundant biomass available for biofuel production that can come from agriculture and forestry residues, perennial crops such as trees and grasses as well as various biomass waste streams . These feedstocks have large production potentials because they are partially produced as by-product today, can be grown on lower quality lands (including degraded and marginal lands of which 100’s of millions of hectares exist) and generally have very good environmental performance due to the lower intensity cultivation, which requires less inputs and operations and leads to more carbon storage below and above ground. The overall result is generally a good GHG profile, sometimes with net negative emissions over the whole value chain. This category of biofuels is generally considered of key importance for medium (2030) to longer term (2050 and beyond) when large volumes could eventually be produced.
Technology readiness levels of advanced biofuels. Source: IRENA