A British technology innovation promises to boost the power available from fuel cells, and bring down the manufacturing costs. Power increases of 16% have already been achieved, and the research team say that 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 Cells (MFC).
Fuel cells are going to be increasingly important in the energy mix, not least because, if they are developed to the right degree of efficiency and performance, they will be suitable for use as a replacement for – among other things – domestic heating boilers which produce harmful emissions. Combined Heat & Power (CHP) plant, especially domestic Combined Heat & Power (dCHP), will be an ideal vehicle for fuel cell application. This is an area, therefore, which may increasingly affect electrical and plumbing installers in the future – possibly within a decade.
dCHP works by using the waste heat produced by power generation rather than rejecting it into the atmosphere. Typically for CHP, the proportion of the used fuel’s energy rises from around 35% (conventional plant) to 85 - 90%. The economic and environmental benefits are well recognised, at least in Europe, and the EC has made increased CHP capacity a key part of its CO2 reduction strategy. The technology is already available for small-scale CHP applications but it needs development to be commercially viable. Typically, such applications demand electrical outputs from 0.5 to 10 kW (3 to 30 kW thermal).
Consumers could cut their home energy bills by up to £200 a year, and their CO2 emissions by up to 25% with domestic CHP (dCHP). The Combined Heat and Power Association believes that ‘domestic CHP puts ‘consumers in the driving seat’ giving them the choice to deliver their own green power - and cut costs. The Energy Saving Trust believes that around 700,000 units could be in place by 2010.
A ‘breakthrough’:
The MFC 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% 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.
How fuel cells work:
Fuel cells generate electricity through a simple electrochemical reaction between hydrogen, the fuel, and oxygen from the atmosphere to produce electricity, heat and water. There are several different types of fuel cell but they are all based around a central design consisting of two electrodes separated by a solid or liquid electrolyte. The PEM cell typically used in automotive and power generation applications uses a polymeric membrane as the electrolyte with carbon supported platinum electrodes. A single cell produces between 0.6 to 0.7 V, so a fuel cell 'engine' for a vehicle has to be built up from several hundred PEM cells stacked together.
What bipolar plates do in fuel cells:
The bipolar plates serve two principal roles in the fuel cell. One purpose is to act as a conductor for the electrical energy. A second purpose is to channel the flow of gases to ensure that the electrode is adequately supplied with reactants. The gases flow in a number of finely detailed convoluted flow field channels, typically 0.5 to 2 millimetre wide and up to 1 millimetre deep, formed in the surface of the plate
About Morgan Fuel Cells:
Morgan Fuel Cells Limited (MFC) is wholly owned by the Morgan Crucible Company plc, a global company engaged in the manufacture and marketing of carbon, ceramic and magnetic materials in a wide range of applications. MFC is based in Stourport, Worcestershire and designs, develops and markets component technologies that address the biggest challenge currently facing the fuel cell industry - the need to deliver material performance enhancements and overall cost reductions to compete with conventional combustion based power generation and advanced batteries.
Eight Grove Fuel Cell Symposium:
MFC presented the results of its research in Biomimetic bipolar plate technology at the Eight Grove Fuel Cell Symposium from September 24 - 26 at ExCel in London's Docklands.
Contact: Victoria Gould
Director of Group Communications
The Morgan Crucible Company plc
( Morgan Fuel Cells )
Tel 01753 837237
Email: victoria.gould@morganplc.com
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