Fuel cell combined heat and power generation: a new efficient and clean energy source for buildings
A fuel cell is a system converting the chemical energy of dihydrogen to electrical energy, heat and water, with high efficiency and low environmental impact. Used as part of building combined heat and power generation systems, the fuel cell is an energy supply innovation.
The installation of a fuel cell combined heat and power (CHP) generation unit is planned for the production of electrical and thermal energy at the new Air Liquide Research Centre. Transport and storage of dihydrogen was not desirable for availability and safety reasons, so the selected system uses natural gas (CH4) as its source of dihydrogen, generated on site and consumed immediately.
The unit can provide local and continuous production of electrical energy used directly in the building to cover the base load. The thermal energy released by the chemical reaction in the fuel cell is recovered in a water circuit for heating the premises. This is the main advantage of CHP generation: the heat produced when electrical power is generated is recovered and used, whereas in conventional electricity generation by power plants, the turbine exhaust steam is discharged into the natural environment. The energy efficiency of CHP generation is consequently substantially higher and saves primary energy compared with separate production of electricity and heat.
It should also be noted that the use of fuel cell technology avoids the emission of pollutants such as sulphur and nitrogen oxides, in comparison with a more conventional CHP system using a combustion engine.
The system has no moving mechanical parts, and is consequently much quieter than combustion-driven CHP generation, while requiring fewer maintenance operations.
Lastly, in the context of our project, the integration of this technology into our overall design has meant that there is no need to install a generator set for the backup electricity supply, as the CHP unit can be used for this purpose in the event of a power cut on the main supply to the site.
A Fuji N2telligence CHP unit with an electrical output of 100 kW and a thermal output of 110 kW has been selected.
The principal advantages of this system can be summed up as follows:
- high efficiency (> 50% electrical and 40% thermal = 90%) compared with conventional electricity generation (30% to 40% without heat recovery),
- double the efficiency = 50% reduction in CO2 emission,
- zero emission of pollutants,
- production as close as possible to the consumption site,