Could hydrogen decarbonise transport?

THE HYDROGEN FUTURE OF EUROPE’S AUTOMOTIVE MARKET

April 2021 saw the latest collaboration in support of fuel cell electric vehicle (FCEV) uptake, with automotive manufacturer Nikola announcing plans to create a hydrogen pipeline and refuelling system across Europe. What technology is required to make hydrogen a viable option both in terms of sustainability and automotive efficiency?

Europe has one of the world’s most developed hydrogen markets and is home to over half of all projects, according to The Hydrogen Council and McKinsey’s Hydrogen Insights Reports 2021. Both the UK and the EU have plans to develop their hydrogen offering and have committed to reach a production capacity of five gigawatts (GW) and 40 GW respectively by 2030.

Despite the maturity of the sector, Europe’s hydrogen still needs considerable development in order to reach net zero targets and to become a viable fuel source for automotive applications. Making usable, renewable hydrogen is no easy feat — so where’s the best starting point?

CLEAN IS GREEN

First, we must consider how we make hydrogen green. Hydrogen can be produced in many ways, each corresponding to a different colour. Most hydrogen produced in Europe is currently grey — it is produced by mixing natural gas and steam to create hydrogen and carbon dioxide in a process known as steam methane reformation.

The problem with this production method is that it relies on a fossil fuel to produce hydrogen, which conflicts with hydrogen’s alleged sustainability superiority over petrol and diesel-powered vehicles.

Ideally, we need to make green hydrogen, which uses renewable electricity to separate the hydrogen and oxygen atoms that make up water in a process called electrolysis. This results in zero carbon emissions.

Geographically, Europe is in an advantageous position thanks to an abundance of renewable energy sources in the surrounding area. The EU’s Hydrogen Strategy Report has already identified North Africa as a priority region for increasing hydrogen availability across Europe, thanks to a plentiful supply of sunlight and subsequent renewable energy.

IMPROVING FUEL EFFICIENCY

Next on the agenda is making hydrogen-powered vehicles commercially viable. According to Hydrogen Mobility Europe, if hydrogen remains at the current low levels of demand, the cost of producing and supplying hydrogen could be passed onto end users. This would mean that hydrogen vehicles would cost more to run than both battery electric vehicles (BEVs) and fossil-fuelled cars. Therefore, any technology that can drive down cost is crucial to increasing uptake.

Fuel cell electric vehicles constantly convert hydrogen into electricity, which in turn charges the vehicle’s battery. In a process known as regenerative braking, most excess energy can be retained to help power the vehicle. However, if the battery is already fully charged or there is a failure in the system, there must be a mechanism in place to dissipate this energy surplus.

A dynamic braking resistor (DBR) is one of the most efficient ways to safely dissipate excess energy and ensure the system remains operational. Cressall’s EV2 DBR is a water-cooled resistor, which allows for safe dissipation without the need for extra components, resulting in an 80 per cent weight reduction when compared to a conventional air-cooled DBR.

These weight-saving properties lighten the load of the vehicle itself, meaning that it can travel further on the same amount of energy. This is particularly advantageous for weight-sensitive freight vehicles, such as pulp and paper or iron and steel transport. What’s more, the weight of a BEV’s battery or the additional components of an air-cooled DBR would reduce the potential load of the vehicle more than a FCEV would, which makes the EV2 and hydrogen a perfect combination for freight transport.

Nikola’s European hydrogen pipeline and fuel system is a landmark step in facilitating widespread uptake of FCEVs. However, if FCEVs are to overtake BEVs, then the refuelling system has to be accompanied by further developments in vehicle efficiency and hydrogen production to make the resource a completely sustainable, feasible option.

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HYDROGEN CATALYST

THE HYDROGEN CATALYST TO THE EV REVOLUTION

 IS HYDROGEN KEY TO THE NET ZERO EV ROLLOUT? 

In November 2021, UK Prime Minister Boris Johnson announced the dawn of the electric vehicle (EV) revolution, fuelled by new regulations and investment pledges across all stages of the EV supply chain. From charging stations to electricity generation, new projects will begin across the United Kingdom in 2022. But there’s one key ingredient that will transform the sector’s sustainability credentials — hydrogen.

With bans on the production of new diesel and petrol-powered vehicles looming, encouraging widespread consumer uptake of more sustainable vehicle choices is becoming an urgent matter. Uptake seems to be increasing — according to The Society of Motor Manufacturers and Traders (SMMT) demand for battery electric vehicles (BEVs) more than doubled between November 2020 and November 2021. But if transport is to decarbonise before its 2050 deadline, there’s more to do to make BEVs carbon neutral.

BEVS’ SUSTAINABILITY SHORTFALLS

Fully decarbonising BEVs is tricky. Using energy from the National Grid means that the sources used for electricity generation directly affect BEVs’ environmental impact. The grid is becoming more renewable and is set to be net zero by 2050. But there is an added challenge. According to The Committee on Climate Change, electricity demand is set to double from today’s 300-terawatt-hour (TWh) requirement to 610 TWh by 2050 thanks to BEV uptake.

So, to complete the dual task of increasing supply and decarbonising electricity generation, the Government is investing in dispatchable low-carbon sources to support variable weather-dependent renewables in powering the grid when production falls short of demand. In the meantime, fossil-fuelled electricity generation is negatively impacting BEVs’ sustainability.

BEVs also have some additional environmental concerns regarding their reliance on lithium-ion batteries. Rare earth metals including cobalt, nickel and manganese are all major components of lithium-ion batteries. Mining these materials can result in huge environmental destruction, disrupting entire ecosystems, while the heavy machinery used contributes even more emissions. So, is there a more sustainable option?

HYDROGEN : THE FUEL OF THE FUTURE

Hydrogen is a promising resource that is key to delivering transport’s decarbonised future. Industrial production of hydrogen is typically delivered through electrolysis — using an electrical current to split water into hydrogen and oxygen. If a renewable source is used to produce electricity, then this creates an entirely carbon-neutral hydrogen fuel, known as green hydrogen.

The Government has set a target to produce five gigawatts (GW) of green hydrogen by 2030 and has already announced investments into projects like Whitelee Windfarm near Glasgow, which will use wind power to generate electricity for hydrogen production.

Hydrogen produced in this way can then be used as a fuel source for an alternative to BEVs: fuel cell electric vehicles (FCEVs). FCEVs are powered by proton exchange membrane fuel cells. FCEVs turn hydrogen into electricity by combining the hydrogen fuel with air and pumping it into the fuel cell. Once inside the fuel cell, this triggers a chemical reaction, resulting in the extraction of electrons from the hydrogen. These electrons then create electricity, which is stored in a small battery used to power the vehicle.

FCEVs fuelled with green hydrogen are completely carbon-free, thanks to the renewable origins of these fuel cells. The only end products of the fuel cell reaction are electricity, water and heat, and the sole exhaust emissions are water vapour and air. This makes them a more-aligned choice with net zero goals, enabling a widespread, carbon-neutral EV rollout.

MAKING HYDROGEN VIABLE

Although the benefits of FCEVs are clear, the technology behind them still needs refining. Fuel cells are unable to work under heavy loads for a long time, which presents issues when rapidly accelerating or decelerating.

Studies into fuel cell function have shown that, when an FCEV begins accelerating, the fuel cell’s power output increases gradually to a point, but then it begins to oscillate and drop despite velocity remaining consistent. This unreliable power output presents a challenge for automakers.

The solution is to install a fuel cell for a higher power requirement than necessary. For example, if a FCEV needs 100 kilowatts (kW) of power, installing a 120-kW fuel cell would ensure there is always 100 kW of power available, even if the fuel cell’s power output drops. Opting for this solution requires a resistor to remove the excess energy when not required, to perform a “load bank” function.

Cressall’s water-cooled EV2 is designed specifically for heavy-duty applications including hydrogen-powered FCEVs. It absorbs excess energy from the system and dissipates it as heat, which can be used to warm the vehicle’s passenger cabin. This protects the electrical system, allowing FCEVs to be very reactive to high-power demands, and accelerate and decelerate rapidly without storing excess energy in a battery.

The EV rollout is well underway, with pressing deadlines for the retirement of fossil fuelled vehicles edging closer and closer. Although BEVs are the main player in the decarbonisation of transport, it’s important to not rule out the distinct benefits that FCEVs bring to the market. But combining the two could be the key to unlocking the EV revolution

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