Hydrogen fuels net-zero mobility

Mark Griffin, Hydrogen Market Development Manager for Clean Fuels, BOC, explains how using hydrogen as a transport fuel benefits councils and fleet operators.

The government’s ‘Road to Zero Strategy’ is driving the transition to zero emissions across all vehicle types for public and private modes of transport. The end of the diesel vehicle is in sight and forward-looking councils and fleet operators are taking action to provide clean transport alternatives, from delivery vans to refuse trucks and bus fleets.

Zero-emission vehicles produce no greenhouse gas or air pollutant emissions at their tail pipes. Currently, only hydrogen fuel cell and pure battery electric vehicles can deliver zero emission transport. Both battery and fuel-cell vehicles use electricity to drive electric motors, and both electricity and hydrogen can be produced using power from renewable energy sources.

Hydrogen as a fuel

Hydrogen is the most abundant element in the universe. It is produced in a number of ways, which vary in efficiency, carbon intensity and cost including as a by-product from the chemicals industry or through a process called steam methane reformation (SMR). It is also possible to produce green hydrogen from electrolysis – a process that extracts hydrogen from water with no emissions.

Hydrogen is stored as a compressed gas at the refuelling station until it’s needed and is then pumped into a vehicle under pressure. One of the key benefits of hydrogen is that refuelling is a fast and familiar process, similar to refuelling a diesel vehicle. It takes around 10 minutes to refuel a bus, which can cover a range of around 350km, and 5 minutes for a car enabling a range of 500km.

There are zero emissions from the fuel-cell vehicle – just clean water from the tail pipe – and they are virtually noiseless.

Refuelling station infrastructure

Refuelling stations need a hydrogen supply, which can either be delivered to site from an offsite production plant or produced onsite. To produce hydrogen on-site, an electrolyser is required to extract hydrogen from water. A compressor unit takes the extracted hydrogen and compresses it for efficient storage. The station also requires a hydrogen store, which is capable of storing hydrogen under pressure, and a dispenser for pumping the hydrogen gas to the vehicle under pressure.

For any refuelling station, ensuring reliability is essential. At BOC’s Kittybrewster facility in Aberdeen, every refuelling has been successful since the station’s launch in 2015, and the reliability rate is 99.5% with no failed refuels.

Also important is the need to ensure that the refuelling capacity is large enough to supply the vehicle fleet for which it is intended. Producing 300kg of hydrogen daily is enough to fuel ten 42-seat buses, with each bus able to travel up to 350km between refuelling. By using a modular design, it is possible to scale up hydrogen production to match the needs of a growing fleet.

Cost of ownership

There are several factors that contribute to the cost of operating a hydrogen refuelling station. Two of the main determinants are the volume of hydrogen produced (cost reduces with increasing volumes) and the cost of electricity used in the electrolysis process. For a low-carbon solution, operators typically source power from renewable sources or a supplier offering a green tariff.

Some operators aim to achieve cost parity with diesel at the pump, while others recognise that there is a significant value associated with reducing air pollution and carbon emissions. Producing hydrogen using methods other than electrolysis does create some CO2 emissions. It can, however, be cheaper, improve local air quality and provide a pathway to using green hydrogen in the future. With any new project, BOC works with local councils and vehicle fleet owner/operators at the outset to help them understand the economics of hydrogen use, align the costs with their objectives and identify potential sources of funding.

Element Energy, a specialist low carbon energy consultancy, reports that by the mid-2020s bus manufacturers expect it will be possible to purchase a fuel cell bus for less than £350k. This cost assumes relatively low production volumes – a few hundred per year. With expansion in the global supply of the key components of fuel cell systems and hydrogen tanks, it is reasonable to expect prices to reduce to below £300k by the end of the decade.

At these bus prices, the total cost of ownership of a fuel cell can fall below even the best case battery electric options (when coupled with the price of hydrogen that will be available at high-volume refuelling stations). Element Energy concludes that, as cities regulate to require zero emission buses during the 2020s, the fuel cell bus has the potential to be a major part of achieving this political ambition.

Renewable energy and grid balancing

With more renewables on the grid, energy supplies are becoming more intermittent, and real-time electricity prices more volatile.

When supply exceeds demand, energy becomes very cheap – sometimes negatively priced, as the alternative is that operators must be paid to curtail generation. Building energy storage facilities helps to balance the grid by storing energy when it exceeds demand, then using it when demand picks up again.

Using electrolysis, hydrogen can act as a very cost-effective energy store and so help balance the grid. The flexibility of the proton exchange membrane (PEM) technology used within the electrolyser enables the electrolysis process to be switched on and off very quickly to respond to electricity price volatility and take advantage of low electricity prices. Hydrogen provides a way to store electricity when it is cheap, which can reduce the cost of hydrogen at the pump.

Established, proven technology

Hydrogen refuelling is in daily operation worldwide. BOC launched the first open access hydrogen refuelling station in Swindon, UK, in 2011. In 2014 the site was further developed to become the first commercial scale production and refuelling station with the installation of an onsite electrolysis unit producing green hydrogen powered by solar. Since then, BOC has been working with partners to develop a public UK hydrogen refuelling network, including the first UK hydrogen station on a public fuel forecourt at Shell’s Cobham service station on the M25.

BOC’s relationship with Aberdeen City Council to develop, construct and operate the Kittybrewster refuelling station, is a major success. Together, they are creating a blueprint for rolling out hydrogen technology across towns and cities in the UK, helping to reduce carbon emissions and air pollution, which is a major benefit for all. https://www.boconline.co.uk