Fuel cells are a clean and environmentally-friendly source of electrical power that have been available for some time. However, due in part to the fact that they need a readily-available supply of hydrogen, their adoption has been somewhat limited. Creating the infrastructure needed for fuel cell powered electric vehicles would require adapting millions of filling stations and has not been considered viable. Fuel cells have found a niche in other applications such as data centres and drones, and a few vehicle applications – provided that hydrogen has been available.
One of the leading advocates of fuel cell propelled cars has been Toyota who used 650V fuel cells in their Mirai model, launched in 2016. While battery-powered cars typically have a range of around 300km, the Mirai has a range of over 500km. Uptake of the car has been limited by the lack of supporting infrastructure to replenish the onboard pressurised hydrogen tanks. However, the situation in Japan is changing and earlier this year they became the first country to reach the milestone of 100 hydrogen filling stations.
Other car manufacturers are showing interest in fuel cell technology. Last year General Motors and Honda partnered in a joint venture to design and manufacture fuel cells. A subsidiary of German car manufacturer Daimler has also been developing fuel cells, although they are considering other applications such as data centres as well as cars.
At the simplest level, a fuel cell comprises a stack of proton-exchange membranes (sometimes called polymer electrolyte membranes (PEM)). The PEM uses a platinum catalyst to release energy by combining hydrogen and oxygen, with the only by-product being clean water (H2O) with none of the poisonous emissions that are seen from internal combustion engines.
Bus operators can benefit significantly from the lower cost of fuel cell propulsion and, as a result, bus manufacturers have been significantly involved in fuel cell development in recent years. As more fuel cells are used, so they will become a more viable technology – working alongside existing batteries or replacing them entirely in some cases.
Fuel cells are making an appearance in commercial vehicles as well. Calstart in California is equipping UPS delivery vehicles in Los Angeles with 30kW FCvelocity-MD fuel cell modules from Ballard Power Systems. Over the next 5 years, 1500 UPS vans will benefit from extended range due to the new fuel cells.
A PEM stack, also from Ballard Power Systems, is being used by Nuvera to enhance the range of vans and busses. The system uses a BAE Systems combined battery and fuel cell hybrid propulsion system and achieves double the fuel economy of busses that run on compressed natural gas (CNG) alone.
In the UK, the Office for Low Emission Vehicles (OLEV) is investing £23 million in fuel cell research, including expanding hydrogen refuelling infrastructure. An initial investment of £9 million will allow seven refuelling stations to be completed by the end of 2019 with another £14 million funding an estimated ten more stations. As these figures show, significant investment is required to develop the infrastructure to refuel hydrogen-powered vehicles on a national basis.
Within the project scope, Liverpool’s ULEMCo has designed a 12kW fuel cell that will sit on the roof of Nissan’s e-NV200 electric van. By being placed on the roof the fuel cell can boost the range without reducing the available load space. In fact, just 1.6kg of hydrogen will add 150 miles to the range, effectively doubling the delivery range compared to a standard e-NV200.
Fuel cells take to the air
Another application for fuel cells is to extend the range of professional unmanned aerial vehicles (UAVs) that are used in a myriad of situations including aerial photography, agricultural inspection, oil and gas platform inspection, parcel delivery and more. Lightweight fuel cells, such as the one recently developed by Intelligent Energy, extend the range of battery-based drones by a factor of three as well as offering a much faster refuelling time.
Companies will be able to use this to improve productivity. One company already benefitting from the technology is PINC, a US-based drone operator. The PINC Air UAV allows companies to use drone technology with RFID sensors and cameras for checking inventory, and the fuel cell keeps the drone in the air longer and on the ground much less.
Fuel cells in data centres?
Even in 2012, Apple was using fuel cells as part of the power system for a California-based data centre. As US-based data centres are expected to consume 140 billion kWh/year by 2020, using hydrogen as an alternative fuel will to generate electricity on site will not only save cost, but also relieve some of the load on the grid. If all of the data centres were powered by fuel cells, this would have the effect of creating 50 new power stations in the US.
Given the potential in this sector, many companies are entering the market. NuCellSys are a subsidiary of car manufacturer, Daimler that is significantly involved in research and development for fuel cells, both for their traditional market of vehicles as well as data centres.
Microsoft is also getting involved at its Advanced Energy Lab in Seattle. Here, each server rack has a dedicated fuel cell to provide electrical power. Advanced monitoring will help Microsoft understand how these cells perform and how they can be better integrated, with the hope that they will be able to halve the energy consumption of these sites. As this is a fixed installation, refuelling is not a challenge, with each cell connected to a natural gas line that powers all of the installation directly.
Solid oxide is another way of keeping fuel cells running and can be easier to implement than liquid hydrogen or natural gas. Equinix is using this approach to successfully 12 US-based data centres.
Even when the refuelling challenge has been fully addressed, current fuel cell technology requires expensive platinum to act as a catalyst. Research is under way to find alternate materials and Ballard Power Systems have collaborated with Nisshinbo in Japan to develop non-precious metal catalysts (NPMC) which have already been incorporated into a fuel cell stack on fork lift trucks.
Fuel cell based batteries
Researchers at RMIT University in Melbourne, Australia are attempting to completely circumvent the issues relating to refuelling fuel cells. Their ‘proton battery’ combines a fuel cell and solid-state hydrogen into a single unit. The technology is based on a carbon electrode that combines with protons from the water. This novel approach offers an improvement from an energy perspective and may also be environmentally cleaner – and lower cost as well.
As the currently popular Lithium-Ion (Li-Ion) technology relies on mineral resources that are becoming scarcer, the proton battery approach may well become significantly more cost effective. The primary material in a proton battery is carbon, which is plentiful and cheap, as is water. The battery is charged up with protons generated by splitting water and then stored in the carbon cathode. This is subsequently released and passed back through the fuel cell to generate power.The first prototype can store as much energy per unit mass as commercially available lithium-ion batteries using a porous activated-carbon electrode made from phenolic resin, and generates 1.2V.