Wärtsilä Fuels Fuel Cells With Landfill Gas
Completes first phase testing of its FC20 solid oxide fuel cell power generating unit that runs on landfill gas
Power plants operating on methane gas derived from landfills are nothing new. And fuel cell power has been making headway of its own. But Wärtsilä has combined the two and
completed the first phase of testing of its FC20 solid oxide fuel cell (SOFC) power generating unit that runs on landfill gas.
Wärtsilä partnered with Topsoe Fuel Cell (TOFC), which provided the SOFC stacks as well as the reformer catalyst to the fuel cell system. Erkko Fontell, director, fuel cells at Wärtsilä, said, “During the testing period of 1500 hours, we have demonstrated that SOFC can be operated
with landfill gas, and the gas can be cleaned sufficiently to ensure successful operation. We have also achieved our target for electrical efficiency and demonstrated that the system can be operated fully automatically even though the gas composition varies with weather
With an output of approximately 20 kW, it is capable of powering 10 households. An exhaust temperature over 400°C allows thermal output ranges from 14 to 17 kW for heat in the local district heating network. The system’s nominal efficiency rating is 43% ac with demonstrated peak efficiency at 47%, said Fontell.
An SOFC operates through three major components: an anode, a cathode and an electrolyte between them. During operation, air is fed to the cathode where it is reduced to form oxide
ions. At the same time, the refined gaseous fuel is fed to the anode. The oxygen ions formed in the cathode travel by ionic transport through the electrolyte to the anode, where they combine with hydrogen and carbon monoxide and oxidize hydrogen into water and carbon monoxide into carbon dioxide.
Through these electromechanical reactions, dc electricity and heat are created. The dc electricity is converted to ac and sent to the local utility. The air supplied to the cathode is
also used to cool the system as it converts energy from the fuel to heat. Impurities in the fuel are cleaned in two phases, Wärtsilä explained. At the landfill, the gas is dehumidified by cooling and condensing the water away from the gas. Then before it reaches the Wärtsilä FC20 unit, an active carbon filter removes remaining impurities. A control system follows the gas compositions and adjusts the flow rate and other system parameters to maintain stable operation, said the company.
Wärtsilä said emissions from the unit are very low and no measureable levels of sulphur oxide or nitrogen oxide are emitted, and that when operating on biogas, CO2 levels are nearly carbon neutral. The system was developed for the Vaasa Housing Fair site for an energy theme and is located in a suburb of Vaasa, Finland. Operation of the site is supported by Wärtsilä’s Vaasa engine laboratory.
The company is also developing a Wärtsilä FC50 fuel cell unit designed to produce nominal 50 kW electrical power, with plans to develop larger units in the future. Wärtsilä said these fuel cells are sufficient for a range of applications, including farmhouses, sewage treatment plants, landfills and commercial buildings that need power and heat, such as hotels, malls and offices.
“We see that there is great market potential for fuel cell application in various distributed generation applications either fueled with natural gas or biogas. We will continue to the development and demonstration of the products in different applications and aim for commercial projects during the coming few years,” said Fontell
Source: Diesel & Gas Turbine Worldwide