BIOHTPEM - Technology development for bioethanol fuelled fuel cell systems
This project is carried out in cooperation between Prototech AS and Weyland AS and is financed by the Research Council of Norway through the RENERGI programme.
The underlying motivation for the project is to reduce greenhouse gas emissions from the transport sector. In the future transport system, there will be a need for various low-emission fuels to serve the various needs. Batteries, hydrogen and bio-fuels are all expected to play an important role. Within heavy transport and ships, there will be a need for liquid fuels to obtain a sufficient operating range. Bio-fuels, such as bioethanol, are climate neutral candidates to serve this market.
Weyland AS in Bergen has developed a method for efficient conversion of biomass waste (lignocellulosis) to bioethanol. This is a second generation bio-fuel, produced from raw material that can not be used as food. Weyland’s process is a so-called strong acid process. It differs from other existing technologies since it removes and recycles 98.5% of the acid used in the bioethanol production. Weyland has installed a pilot plant in Bergen to demonstrate the commercial viability of the technology.
Bioethanol can be used as a fuel additive in combustion engines. However, the efficiency of such engines is low, typically 20-30%. In order to increase the efficiency, the project investigates the opportunity to convert bioethanol directly to electricity by using fuel cells. Fuel cells typically have an efficiency of 40-60%. In addition to increasing the efficiency, fuel cells have an extra advantage: In order to use bioethanol in combustion engines, all water has to be removed from the product. This requirement does not apply for bioethanol to be used in fuel cells. Hence, the bioethanol production process may be simplified, reducing the cost and improving the total efficiency from biomass to electricity.
The type of fuel cells that is relevant for such applications is high temperature PEM fuel cells or solid oxide fuel cells. Prototech has a long experience with these technologies from previous projects and development work. The project investigates the possibility to use bio-fuel directly in fuel cells, but also to transform the bio-fuel to hydrogen-rich gases in a reformer before entering the fuel cell.
The project contains the following activities:
- Investigate direct conversion of bioethanol in fuel cells
- Develop and test a reforming unit for bioethanol
- System design and cost estimates for bioethanol/fuel cell systems
- Testing of HTPEM fuel cell stack on bioethanol
- Production of bioethanol from lignocellulosis for use in fuel cells
The project status, as of May 2011, is as follows:
A literature survey within direct oxidation of bioethanol in HTPEM fuel cells and SOFCs has been carried out. Also, available literature on ethanol reformers has been reviewed as input to the reformer design activity.
A small-scale test reactor for testing of reformer catalysts has been designed and built (see upper right picture). The reactor was used to test a candidate catalyst for ethanol steam reforming. A set of tests were carried out to measure the efficiency of the reformer reaction for the given catalyst with corresponding temperature profiles in the catalyst volume under various operating temperatures.
A bioethanol reformer has been designed (see picture to the right) and is currently being manufactured and assembled. The reformer is an integrated reformer and burner to provide reformate for a 1 kW fuel cell. A test rig for the reformer is under construction in order to do performance and operation tests.
System simulations on a HTPEM/reformer system were carried out in HYSYS showing that an additional water shift reactor is necessary to reduce the CO content of the reformate before entering the fuel cell. The simulated system can be feasible for stationary systems or in ships, but will probably be too complex for use in land based transport. A component list has been established, forming a basis for the cost analysis. System simulations were repeated for a SOFC/reformer system and are currently under optimisation.
A test rig for a HTPEM stack has been built and initial tests carried out to map investigate feasible operating conditions and start-up/shut-down procedures. Tests of the stack with bioethanol/reformate are under planning.