The difference between green and grey energy
Decarbonisation means replacing fossil fuels as a power source, not just to drive cars, but in all other industrial aspects as well.
What are grey and green energy?
Grey Energy
By now, battery-powered vehicles are a common sight on our roads.
By comparison, hydrogen powered vehicles are extremely rare.
What the two have in common is that they are only as green as the energy they are powered with.
If the electricity a battery-powered vehicle is charged with comes from a coal-fired power station, its environmental advantage over traditional combustion-engine powered vehicles is drastically curtailed.
This is an example of grey energy.
It comes in a green cloak, but underneath it is exactly as damaging to the environment as before.
Green Energy
Green energy, by comparison, is energy that has been derived from renewable sources, more specifically from photovoltaics, wind turbines, hydroelectric (and, increasingly, tidal power stations).
Gigantic wind parks are an old hat by now, and so are solar parks.[REF02]
These two have in common that they are typically located far away from where the energy they generate will be used:
Wind parks are often found offshore and solar parks are often found in desert areas.
This raises the question of how to get the energy to where it is needed.
All renewable sources of energy listed above produce the energy in the form of electrical energy, so one way of transporting the energy is to connect the solar or wind parks to the national grids with a cable.
However, this way of transporting energy has got some drawbacks, such as the cost of the cable and the losses due to the electrical resistance of such a long cable.
One way around this problem is to turn the electricity into hydrogen (H2) by electrolysing water.
Obviously, this works only for offshore wind parks, because there is not enough water in the desert to be electrolysed.
Offshore wind parks are standing right in the water and generating the hydrogen right at the source eliminates all the transport losses.
The hydrogen can be pipe-lined to the shore.
Applications of green hydrogen
Mobility
The first application coming to most peoples’ mind is probably mobility.
Here, it has to be kept in mind that the term ‘mobility’ encompasses a lot more than driving a car.
As stated above, there are hydrogen-powered cars, albeit pitifully few.
The reasons for this are that the fuel cells which turn the hydrogen back into electricity are still way too expensive to be competitive, at least at present.
A brief introduction into how fuel cells is given in our previous article “Why there is no hydrogen economy”.[REF03]
A quick look at the history of the battery car shows that mass production will drastically lower the price of initially quite expensive technology, and indeed most major car manufacturers are active in the hydrogen market, be it for passenger or haulage vehicles.
Another reason for the low numbers of H2-powered cars is the low number of petrol stations at which hydrogen is available — the infrastructure is just not there.
This, however, is less of a problem if you think of replacing diesel-powered railway engines.
There are still many kilometres of non-electrified railway lines which are served by diesel-powered railway engines.
Here, there would be no need to build up a network of petrol stations, the installation of a few strategically placed H2-tanks at the train depots will suffice.
The same goes for buses because buses don’t take their petrol at any old petrol station somewhere along the road, they get refilled at the depot.
Hence, hydrogen supply points would only have to be installed at the depots.
Conceptionally somewhere between individual and public transport as delineated above sits the haulage industry, and things are beginning to move away from diesel and towards hydrogen here too.
Powering trucks with batteries like in the case of passenger cars is not an option, as the batteries required would be too big and too heavy to be practical.
Here, a scarcely developed hydrogen infrastructure may suffice.
Switzerland has started a big test run with H2-powered trucks.
To offset the still exorbitant costs of H2-powered trucks they are heavily subsidised, and the haulage industry is incentivised by substantial tax rebates.[REF04, REF05]
The key to integrating hydrogen into our mobility lies in
- a) the cost of the fuel cells which recombine the hydrogen with oxygen to give water and electrical energy, and
- b) finding areas of application in which investments into infrastructures are required at critical locations.
It should therefore come as no surprise that the biggest aircraft manufacturers pursue active research into hydrogen-powered planes, [REF06, REF07] and just like some offshore wind farms produce hydrogen at the source as it were, there are plans for cargo ships as well.
These ships would be equipped with wind turbines, which provide the electricity necessary to generate hydrogen on board.[REF08]
And apart from mobility?
Transport is a big polluter, but other industries consume vast amounts of energy too, such as the steel and cement industries.
These industries will have to change their ways of working too, and they are at least beginning to think of it.
One example is the collaboration between Mitsubishi Heavy Industries and Primetals Technology in Australia to form a research centre looking into ways of using hydrogen as the power source for the heavy industry.[REF09]
Conclusion
At the beginning of this article, we posed the question of what is green and what is grey energy.
We pointed out that a battery powered car is not really green if the electricity on which it runs still comes from fossil fuels.
We then outlined how hydrogen generated from renewable energy sources could play an important role in decarbonisation.
The conclusion is therefore:
Energy from renewable sources is the primary bottleneck on the way to decarbonisation.
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01) https://en.wikipedia.org/wiki/Offshore_wind_power/, last accessed 2021.09.10
02)https://www.pv-magazine-australia.com/2019/06/11/an-overview-of-the-worlds-largest-solar-parks/, last accessed 2021.09.10
03) https://www.science-by-trianon.com/post/why-is-there-no-hydrogen-economy
04) https://www.trtworld.com/life/hyundai-s-hydrogen-powered-trucks-aim-to-conquer-swiss-alps-34198/, last accessed 2021.09.10
05) https://www.swissnewsdaily.ch/2021/01/13/hyundai-delivers-first-hydrogen-powered-trucks/, last accessed 2021.09.10
06) https://en.wikipedia.org/wiki/Boeing_Phantom_Eye/, last accessed 2021.09.10
07) https://www.airbus.com/innovation/zero-emission/hydrogen/zeroe.html/, last accessed 2021.09.10
08) https://www.statkraft.com/newsroom/news-and-stories/archive/2021/hydrogen-deliveries/, last accessed 2021.09.11
09) https://hydrogen-central.com/hydrogen-ironmaking-mitsubishi-heavy-industries-australia-primetals-technologies/, last accessed 2021.09.11
