Is hydrogen a sustainable energy source?


In 1999, General Motors hydrogen fuel cell pioneer Byron McCormick coined the phrase “energy security” when he said, “There may even be issues of war and peace. How right he was, and if ever there was a time to focus minds on the urgent need for sustainable energy, this is it.

In addition to fuel cells, there is a slow but growing trend in the development of hydrogen combustion engines. JCB proves this with its work on hydrogen combustion engines and Toyota is exploring the same concept with car engines.

This has been tried in the past, of course, with port-injected gasoline engines, but the low volumetric efficiency of burning hydrogen gas in an engine designed for atomized liquid fuel meant greatly reduced specific power (hp per litre) and higher emissions. Direct injection and high compression ratios in purpose-built combustion chambers have changed that, which is why JCB and Toyota are succeeding with the latest engine and electronic hardware.

That said, many leading engineers and scientists working in the field of sustainable energy consider batteries to be a better solution for storing electricity than hydrogen. They point out that the process of generating electricity sustainably, then turning it into hydrogen, then consuming energy to compress it and even more to deliver it to a vehicle is far less efficient than simply generate electricity and store it in a battery.

It may be possible to improve the energy equation in one step of this process, however, by compressing the hydrogen as it is produced through the use of high differential electrolysis rather than a mechanical pump . Conventional electrolyzers produce hydrogen at relatively low pressure, but the “high outlet pressure” design (first tested by Honda in 2010) has since been used to fill the compressed hydrogen tanks of cars with fuel cell at 300 bar. It is now able to fill them at 700 bar, the pressure necessary to achieve autonomy with a hydrogen fuel cell comparable to that of conventional cars.

In addition to improved energy efficiency, there are also operational benefits. In existing retail hydrogen filling station installations, 13% of maintenance time is spent on mechanical compressors, an additional cost that could be removed from the equation.

Interest in hydrogen as a domestic gas is growing and trials are underway in the UK to assess the viability of diluting natural gas with 20% hydrogen. At Cop 26, the government announced the Whitelee project near Glasgow, which will generate and store enough green hydrogen to power 225 buses from Glasgow to Edinburgh daily. The hydrogen will be generated by Scottish Power Whitelee Windfarm and converted into hydrogen by what will be the UK’s largest electrolyser to date, produced by ITM Power.

Knowing that one of the major advantages of hydrogen is also to store the energy generated during off-peak periods by converting it into hydrogen, the Whitelee project should demonstrate an approach to sustainable energy that has been talked about for two decades but which has until now required a real incentive to become a viable reality. The pressing need for energy security today may well be that.

Charge faster: good idea
Ford in the US is working with a research team from Purdue University to develop a cooled fast charger cable to enable fast charging times in line with the time needed to refuel gasoline or diesel. Rather than just liquid cooling, the cable’s coolant “phase changes” from liquid to vapor, dramatically increasing the amount of heat removed. However, the project is still in its early stages and prototype testing won’t begin for about two years.


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