From 1st- to 2nd-generation biofuel technologies - An overview of current industry and RD&D activities

Nov 2008

In order to move away from sole dependence on food crops towards the conversion of lignocellulosic feedstocks to bioethanol, synthetic diesel and aviation fuels, the necessary transition from 1st- to 2nd-generation biofuels will require major steps forward - but the pathways and timelines are unclear. It is recognized that 2nd-generation biofuels generally have several advantages over both fossil fuels and many 1st-generation biofuels. These include reduced GHG emissions, a more positive energy balance, and better access to sustainable biomass feedstocks allyear-round in order to keep the conversion plant operating and hence spread the annual overhead costs over a greater number of litres of biofuel produced. The challenge for a project developer is to procure sufficient feedstock from within a reasonable transport radius of the plant over the long term.
The commercialisation of 2nd-generation biofuels will have implications for many developing countries that are actual or potential biofuel producers, consumers and exporters. If carefully managed, development of these technologies offers the promise of sustainable development, rural revenue generation, and mitigation of the impacts of environmental changes worldwide.
Whilst 2nd-generation biofuels are being demonstrated, other concepts are being tested at the R&D and pilot scales. These advanced systems include algal oil production and novel conversion technologies. It is also recognized that in a situation analogous to the refining of crude oil to produce multiple, higher value chemicals and plastics, that in the medium- to long-term biofuels will likely be produced not only in conjunction with heat and power, but also with other biomaterials and chemicals to enable the ‘bio-refining‘ of biomass to serve multiple purposes. Once successfully developed in OECD countries currently investing in bio-refinery RD&D, technology transfer will enable many other countries to also benefit.
The aims of this report therefore are presented in three separate parts:
Part A) - to assess the status and markets of 1st -generation biofuels and the opportunities and barriers to future expansion. A general introduction reviews the current markets, drivers and future projections. A broad assessment of 1st-generation biofuels is then made, including the latest technology developments to reduce costs and the barriers to increasing their deployment and future growth.
Part B) - to outline the state-of-the-art of the technologies and costs relating to feedstock production, supply chain logistics including storage, and the various conversion processes employed for 2nd-generation biofuels. Detailed analysis of the status of 2nd-generation technologies has been undertaken and the transition from the more mature 1st-generation technologies evaluated.
Following a review of new crops that could provide 2nd-generation feedstocks, a basic introduction to ligno-cellulosic feedstocks is then provided, including those sourced from agricultural crop residues, forest arisings, wood process residues, and specialist energy crops.
This leads on to a detailed exploration of the two major pathways for 2nd-generation conversion technologies:

  • biochemical processes that utilise enzymes (or acids) to isolate the building-block chemicals from ligno-cellulosic feedstocks to produce ethanol; and
  • thermo-chemical processes that either initially reduce the ligno-cellulosic feedstocks to their most basic gaseous components through gasification before re-constituting them into a range of liquid biofuels, or pyrolyse the solid biomass into liquid ―bio-oil‖ before refining it into useful biofuels and chemicals.
Part C) – to present the research status of advanced biofuels, for example, feedstock produced from algae, conversion by hydrogenation and bio-refineries. The concept of a bio-refinery that produces biofuels together with multiple co-products such as materials, chemicals, and heat and power is explored. Also considered are advanced bio-refining platforms that could link elements of both biochemical and thermo-chemical systems in order to optimise the use of limited biomass feedstocks from both the economic and environmental perspectives.
Recommendations for future policies to support and encourage biofuels are given.
This Report provides a contribution to the Global Bioenergy Partnership (GBEP).
Click here to download the Executive Summary.

By: International Energy Agency (IEA)

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