Proceedings

Abstract: 

Declining petroleum resources, increased demand by emerging economies, and political and environmental concerns about fossil fuels are driving the search for new sources of renewable fuels. Currently the only sustainable source of organic carbon is biomass, but biofuel production must target idle and marginal land and use of wastes and residues so that it does not contribute to rising food prices that adversely affect the poorest.  In order to achieve such a vision, the FP7 collaborative research project SUPRABIO aims to deliver novel unit operations that can be integrated into economic biorefinery options for the sustainable production of biofuels.

Volatile fatty acids (VFA) offer a possible route for such an option.  VFA may be economically produced on relatively small-scale from different waste sources and locations to allow a distributed production system to be realised.  The remaining challenges include more efficient substrate hydrolysis to achieve greater VFA yield; effective VFA recovery and low cost catalysts as well as more innovative reactor designs for economical fuel production.

This paper will provide an overview of this new waste management option as well as the lab results of pre-treated sludge fermentation for VFA production.

Key words

Second generation biofuel; sludge management; technology assessment; environment; resource recycling; sustainability

Introduction

Declining petroleum resources, increased demand for petroleum by emerging economies, political and environmental concerns about fossil fuels are driving our society to search for new sources of fuels, particularly for transportation purposes. Currently the only sustainable source of organic carbon is biomass, which is abundant throughout the world.  EU Renewable Energy Directive requires Member States to meet Renewable Transport Fuel Obligation (RTFO) target of 5% by 2010.  However, this has been met mostly through the import of so-called First Generation Biofuels at a considerable social cost.  In 2008 Secretary of State for Transport Ruth Kelly invited the Renewable Fuels Agency to undertake a review of the Indirect Effects of Biofuels (The Gallagher Review, 2008). According to Gallagher there is probably sufficient land for food, feed and biofuels, but biofuel production must target idle and marginal land and use of wastes and residues.  Presently biofuels contribute to rising food prices that adversely affect the poorest.  Current evidence suggests that the proposed EU biofuels target for 2020 of 10% by energy is unlikely to be met sustainably and the introduction of biofuels should therefore be slowed while we improve our understanding of indirect land use change and effective systems are implemented to manage risks.  Specific incentives must also be provided to stimulate advanced technology development.

The EU is currently supporting a number of research projects that aim to deliver more efficient biorefinery technologies under the European Commission’s Sustainable Biorefineries Programme (FP7-2009-BIOREFINERY-CP).  For example SUPRABIO, a large-scale collaborative research project involving 16 European organisations (http://www.suprabio.eu/).  Its overall objective of is research, development and demonstration of novel intensified unit operations that can be integrated into economic and sustainable biorefinery options for the production of second-generation biofuels, intermediates and high value products, together with assessment of the outcomes to inform and enable sustainable implementation.

Under SUPRABIO Volatile fatty acids (VFA) are considered as a possible route for second-generation biofuels.  In this paper we aim to provide a detailed description of this novel concept, how it may be implemented in practice, bench scale results and a review of the foreseeable challenges.