Calibration
The future of hydrogen vehicles
You can’t trade it if you can’t measure it
If hydrogen is successfully going to be used as an alternative fuel, it needs to be measured effectively (like petrol is now) but there are all sorts of issues with accuracy and the calibration of delivery mechanisms. Marc MacDonald, project engineer at TÜV SÜD National Engineering Laboratory, investigates...
H
ydrogen is recognised as playing a crucial role in global zero net carbon targets, through its potential use in
vehicles and in domestic heating. This is because hydrogen contains no carbon, so when used in a fuel cell or combustion engine its only product is water vapour. However, due to the low abundance of elemental hydrogen in the earth’s atmosphere, hydrogen needs to be produced first before it is used as a fuel. This means that it is referred to as an energy carrier and unlike hydrocarbons is not an energy source. When discussing the use of hydrogen in a
low carbon economy, ‘green hydrogen’ is commonly referred to; this is hydrogen generated from the electrolysis of water using renewable energy such as solar, wind and tidal. Generation of hydrogen from renewable sources provides a buffer which would allow excess energy to be stored in periods of peak
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generation. However, the most common method for producing hydrogen is either through steam methane reforming (SMR) or auto-thermal reforming (ATR) of hydrocarbons such as natural gas, primarily due to the lower costs relative to electrolysis. This process produces carbon dioxide as a by-product, and thus carbon reducing technologies, such as Carbon Capture, Utilisation and Storage (CCUS), are required to avoid carbon dioxide being released to atmosphere. When a carbon reduction technology such as CCUS is used alongside SMR or ATR, the hydrogen produced is commonly referred to as ‘blue hydrogen’. Use of hydrogen as an alternative to refined oil products and natural gas for transport is currently receiving a lot of attention. Like battery powered electric vehicles (BEVs), the use of hydrogen fuel cell electric vehicles (FCEVs) will reduce local air pollution due to the absence of tailpipe emissions. Provided that
either green or blue hydrogen is used, overall carbon dioxide emissions will also be reduced. For BEVs, which use electricity from the electricity grid, the 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. Globally, there are significantly more BEVs than FCEVs at present, and it is easy to see why. The capital costs associated with building a hydrogen refuelling station mean that they are less common than the relatively low-cost BEV charging points.
Despite the capital costs required for
hydrogen refuelling stations, 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. In addition, FCEVs can be refuelled in a few minutes, whereas BEVs can take several hours to recharge their batteries.
September 2020 Instrumentation Monthly
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