Background The EU aims to transform Europe into a highly energy-efficient and low greenhouse-gas-emitting economy. It has made a firm, independent commitment to achieve at least a 20% reduction of greenhouse gas emissions by 2020 compared with 1990 levels. Moreover, within the Energy Policy for Europe (EPE), the European Council endorses the target of a 20% share of renewable energies in overall energy consumption in the EU by 2020. In this context, wastewater treatment plants (WWTP) must be considered from an energy perspective, both in terms of levels of consumption and the use of ‘green’ energy. Anaerobic digestion (AD) is widely used to treat wastewater sludge. This process produces a biogas rich in methane and carbon dioxide that is a renewable energy source suitable for replacing fossil fuels. Traditional CHP units have been widely used to produce electricity from this biogas. New promising technologies, such as hydrogen fuel cells, have however been developed which offer both higher efficiency and a lower environmental impact. Objectives The BIOCELL project aimed to demonstrate the low environmental impact, feasibility and economic viability of energy production from biogas via fuel cells adapted to WWTP. It furthermore aimed to provide the necessary tools for its industrial implementation. The project planned to test energy production from both proton exchange membrane fuel cells (PEMF) and solid oxide fuel cells (SOFC). A PEMFC unit treating 10 m3/h biogas – including catalytic reforming and purification, and H2 storage – would be operated in the WWTP of Murcia. An SOFC unit treating 5-10 m3/h biogas would be operated at a WWTP in Catalonia. Through the two pilot schemes, the project assessed the energy self-sustainability and economic viability of energy production from WWTP biogas via fuel cells and analysed the most adequate treatment for each biogas recycling route considered. The project also aimed to produce guidelines on the choice, implementation, operation and optimisation of energy production from WWTP biogas, providing technical details on every stage of the energy production process. It expected to demonstrate the economic and environmental potential of this technique and to provide the practical information necessary to see it implemented in plants across Europe. The technique would reduce the environmental impact of these WWTP and increase the supply of clean energy. Results The BIOCELL project tested the viability of two methodologies – energy efficient fuel cells – for producing electricity from the biogas produced at WWTPs: Solid Oxid Fuel Cell (SOFC) and Proton Exchange Membrane Fuel Cells (PEMFC). In order to carry out these tests, it designed and constructed two prototype plants at two different WWTP. PEMFC prototype plant: The plant built in the WWTP of Murcia was designed to produce 3 kW of electric power using 10 m3/h of biogas. First, the biogas is cleaned with a caustic scrubber, followed by adsorption on activated carbon and silica gel to dry the gas. Since the PEMFC needs hydrogen as a inlet gas, the methane from the biogas has to be converted into hydrogen (a process called reforming). The reforming step is highly technological and thus a very innovative prototype had to be designed for this purpose. SOFC prototype plant: The plant built in the WWTP of Mataró operates at a high temperature (800ºC) and produces electricity and heat for a total of 2.8 kW power and 1 kW heat using 10 m3/h of biogas. The biogas is first cleaned with a biotrickling filter to remove the H2S. The biogas is then further purified by the adsorption on iron oxides, dried and further purified with activated carbon before entering into the fuel cell. The tests carried out in both plants allowed the project team to draw and to publish guide for WWTP managers for implementing similar electricity generation systems at their plants. This guide also includes an economical study and an environmental assessment. The results of the project showed that both plants are technically viable, environmentally friendly and could provide up to 60-70% of the electrical needs of a WWTP. However, the size of the plant wasn’t sufficiently large to confirm whether up-scaling is feasible or economically viable. Further investment must be carried out by all the sides. On the one hand the producers of fuel cells and WWTPs can learn from the experience of these prototypes , whilst the public administrations by facilitating the investments and providing subsidies. The BIOCELL project also demonstrated economic benefits. The cost for sludge treatment is reduced by the use of biogas energy which is produced during the anaerobic digestion of the sludge in the WWTP and which is then transformed into electricity. Furthermore, the WWTP is self-sufficient from an energetic point of view, as the produced energy can be used to heat the digesters, dramatically lowering the natural gas consumption. Finally the produced electricity can be used to cover a part of the electrical needs of the installation. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).