Background High temperature fuel cells offer several environmental advantages: reduction of carbon dioxide (CO2) emissions, primary and network energy savings and clean atmospheric releases. Builders of fuel cells, such as MTU and Siemens, have constructed cells for demonstration purposes for several sectors. The systems are not expected, however, and are only just starting to be marketed. At the project start date, the use of such fuel cells for collective housing had not been tested in Europe. Objectives The FUEL CELL IN PARIS project aimed to install a high temperature fuel cell in a boiler-house in a 280-unit building in Paris. The objective was to reduce the amount of CO2 released by thermal installations in the housing sector, which accounts for 19% of the EU's greenhouse gas emissions. The Paris pilot site would advance knowledge of energy control problems in urban centres. The results of the project would be compiled and the technology assessed and compared with conventional energy production systems. Results Cellia, the first fuel cell in a city-centre public housing complex, was introduced in Paris in November 2006. Since March 2007, Cellia helped supply heat and domestic hot water to 283 housing units at Porte Brancion managed by the Paris public housing office (OPAC). To date, Cellia has operated for 5,100 hours and generated 806 MWh of electricity and nearly 374 MWh of heat. The application of this innovative system to public housing is a first in France and Europe as a whole in terms of power and technology. The project has demonstrated the technical feasibility of this forward-looking solution, which offers clean, low cost (it reduces heating costs by 10% on average through the re-sale of electricity) steady heat in a way that is compatible with sustainable development. Other advantages of this system include the lack of mechanical wear and tear, noise and vibrations. Moreover, the system is highly efficient and emits less greenhouse gas into the atmosphere. The system does not emit NOx, SOx and produces 30% less CO2 on average than a traditional combined cycle gas boiler and steam turbine. The system’s performance is slightly below the manufacturer’s specifications. Fine-tuning is required for the fuel cell to achieve its promised performance, but after a few problems at the start of the project, net electrical efficiency did exceed 41% and the fuel cell operated steadily. Exhaust produced during nominal output was generally in line with expectations and complied with initial specifications. The system does not emit any sulphur compounds, as they are trapped by activated carbon filters when the natural gas is channelled into the fuel cell. An analysis of the breakdown of maintenance costs shows the importance of auxiliary gases to start up and shut down the system, in particular nitrogen to inert the fuel cell during shutdown. To make these systems marketable, manufacturers will have to make substantial progress in this area, for example by shortening transitional phases and reducing the cost of auxiliary gases. The system has not been in operation long enough to get a meaningful estimate of the average cost of maintenance. The project won a prize at the 2007 Festival International des Médias Audiovisuels Corporate (FIMAC) Film Festival in the section "Engineering, industrial and technical processes, innovations, research and development". Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section). This project has been selected as one of the 17 "Best" LIFE Environment projects in 2008-2009.