7 October 2003 – A technology innovation by a British company promises to boost the power available from fuel cells, and bring down the manufacturing costs. Power increases of 16 per cent have already been achieved, and the research team say there is more to come. The development brings forward the day when fuel cells will be commercially viable for mass-market automotive and general power applications, say the developers, Morgan Fuel Cell (MFC).
The breakthrough is in the design of the bipolar plates that are a key component in fuel cells. The patented “Biomimetic” bipolar plate technology developed by MFC drew its inspiration from the natural world. It mimics the structure seen in animal lungs and plant tissues to allow the gases to flow through the plate in a far more efficient way than has ever been achieved before. The Biomimetic plates also have the added advantage of being produced using MFC’s patented ElectroEtch system, which allows them to be manufactured at a fraction of the time and cost of conventional methods.
Dr Mark Turpin, Global Director of Technology for MFC, explains: “We realised by looking at how animal lungs and plant leaves ‘breathe’, that a structure consisting of large distribution channels feeding progressively smaller capillaries is the most efficient way to distribute reactants.
“So we mimicked this approach in the Biomimetic plate, with a highly branched flow field that distributes gas through a fine system of capillaries. This structure reduces the pressure drop found in the industry-standard serpentine design of flow field and ensures a more even delivery of gas across the bipolar plate, so that more power can be extracted from the fuel cell. Initial results are very promising, with tests already confirming a 16 percent increase in peak power, and we are certain that even more significant improvements can be made.”
Using a Biomimetic flow field pattern also offers the possibility of significant indirect performance and cost benefits. These include improved water management (water being a by-product of the fuel cell process) and reduced overall pressure requirements.
MFC has focused mainly on the graphite bipolar plates featured in PEM (proton exchange membrane) type fuel cells used typically in automotive and general power replacement applications. However, Biomimetic flow field designs are potentially applicable to ceramic and metal bipolar plates and the core design has been adapted for use in direct methanol fuel cells and may find application within solid oxide fuel cell systems.
ElectroEtch manufacturing technology
Key to the creation of the Biomimetic plate design is MFC’s patented ElectroEtch manufacturing technology, which uses a high-precision grit blasting technique to produce a plate in a matter of minutes. This offers a rapid prototyping capability, from drawing to finished plate in about two hours, that enables many different plate designs to be evaluated. And there is no extra cost for complexity, as it takes the same time to etch a complex pattern as a simple one. In the long term ElectroEtch offers the prospect of a low-cost, scalable route for the production of the large volumes of high- performance bipolar plates that will be needed if fuel cells are to succeed in mass-market applications.