Batteries & Fuel Cells
Batteries vs fuel cells for zero emission vehicles
By Richard Poate, senior manager at TÜV SÜD, a global product testing and certification organisation
construction, and manufacturing processes means their safety has dramatically improved. As battery electric vehicles (BEVs) are recharged from the electricity grid, overall carbon dioxide emissions will be reduced if the method of electricity generation emits less carbon dioxide per charged vehicle than those which use hydrocarbons as a fuel. Likewise, hydrogen fuel cell electric vehicles (FCEVs) have no tailpipe emissions, so provided that either green or blue hydrogen is used, overall carbon dioxide emissions will also be reduced.
Refuelling challenges T
he UK Government’s ten-point plan sets out its approach to accelerate net zero goals. Part of this will see the sale of new fossil fuel cars and vans banned after 2030. Vehicle manufacturers are therefore investing heavily in electric vehicle R&D to radically transform the way we drive, and battery development is at the heart of this process. However, while consumers are familiar with the traditional combustion engine, and therefore accept the well-known risks associated with fossil fuel powered cars, there is still an element of distrust relating to relatively new and unfamiliar electric vehicle technologies. According to the International Energy Agency (IEA), in 2019 electric cars registered a 40% year-on-year increase in sales. It puts part of this growth in demand down to significant improvements in technology. For example, research from the IEA reveals that the 2018-19 versions of some common electric car models display a battery energy density that is 20-100% higher than their counterparts in 2012, with battery costs decreasing by more than 85% since 2010. Lithium-ion (Li-ion) batteries have therefore proven invaluable in electric vehicle development, and improvements in design, materials,
28 April 2021
One aspect that is commonly overlooked for FCEVs is the ability to effectively trade hydrogen. To achieve net-zero, a substantial portion of vehicles will need to be hydrogen powered, but consumers will not buy such vehicles until they can easily refuel them. That will require accurate measurement of the fuel delivered, so they pay for what they get, and a widely available refuelling infrastructure, so they can get to their destination reliably. It is therefore no surprise that globally there are currently significantly more BEVs than FCEVs, as the capital costs associated with building a hydrogen refuelling station (HRS) mean that they are less common than the relatively low-cost BEV charging points. In the UK, only a handful of hydrogen refuelling stations exist, compared to nearly 100 in Germany - which has set out clear milestones to increase this significantly further. However, FCEVs do have several advantages, such as a larger range of 400 km and above, compared to a range of around 250 km for BEVs. This is because, when compared with fuel cells and petrol/diesel engines, battery packs store much less energy
Components in Electronics
by weight. On range alone, hydrogen seems to have the upper hand.
In addition, FCEVs can be refuelled in a few minutes, whereas BEVs can take several hours to recharge batteries. For example, while Tesla supercharging stations have a 20-minute charging time this only delivers an 80% charge to protect the battery from high temperatures. After that the rate of charge decreases significantly. For home charging, the charging times are usually many hours, which is only easy for car owners who have their own driveway.
As FCEVS can travel further distances than BEVs and have shorter refuelling times, they are more suitable for the long haul and heavy loads required by HGVs. However, clearly BEVs still have a significant role to play in our quest for net zero as they are more suited to domestic situations that allow for a longer recharging downtime, such as overnight before morning commutes.
Tools in the box
To realistically meet 2030 vehicle targets and hit net zero ambitions, the answer should be to combine the use of both battery and hydrogen fuel cell technologies. Harnessing the benefits of both technologies will deliver
the high-performance systems associated with the traditional combustion engine while reducing carbon emissions.
A vehicle will always need a battery system to support its many functions, but fuel cells can enhance their performance. For example, by solving the issues of distance and charging/ refuelling times currently associated with pure BEVs. This is because the fuel cell can be used to charge the battery, as petrol hybrid vehicles do today.
However, batteries are more capable of effectively managing the various simultaneous energy load demands of a vehicle. The battery management system monitors vehicle safety and performance, with state-of-health functions determining battery degradation and end of usable life. 5G will also be a driver of smart battery maintenance, using real-time data to optimise battery charging and discharging, and support predictive maintenance and failures, as well as remote troubleshooting. It is therefore not a question of either/or, as both battery and fuel cell technologies fill the operational and performance gaps of each other. The future of zero emission vehicles will be powered by both.
tuvsud.com/uk
www.cieonline.co.uk
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