Mark Howitt Interviewed on the Energy Transition

We spoke to one of our Directors, Mark Howitt, about the current state of the energy transition the next steps to building enough long-duration storage. Here are his answers.

How do you feel the energy transition is progressing, in the electricity systems?

In the UK, Europe and North America, there’s huge growth in renewable and clean energy, and short-duration storage. But long-duration storage just hasn’t been built, which is what’s increasing the cost of electricity exponentially — the Putin premium is merely the icing on the cake.

Despite their fossil fuel investments, China is also investing heavily in renewables — and in Compressed Air Energy Storage, of which they have one built recently and eight in the pipeline despite their higher cost and lower efficiency — so their prices aren’t rocketing in the same way. Most of the rest of the world has to catch up, though India’s working developing renewable generation fast.

What needs to be done to get enough long-duration storage built?

First-of-a-kind plants need to be supported and encouraged, in all technologies that offer a potential solution. The support to them could be limited so only the most cost-effective would be built. Then they need contracts that suit them: all such technologies have long construction lead times (the biggest issue being the time that grids take to make the connections) , and are naturally inertial so they deliver a range of services to the grid that can’t be delivered separately – and so should be contracted together.

Please explain that last point.

When inertial generation and storage deliver energy, including balancing services, they spin. Therefore they concurrently deliver inertia, other stability services, reactive power and load, voltage and frequency control, and restoration services naturally – and can’t deliver the energy without delivering all these. So where these services are contracted separately, those contracts must be linked for inertial generation and storage.

Many say that these will be resolved with hydrogen powered generation: what do you think?

If seasonal storage is needed (and the jury’s still out on that), then hydrogen-powered generation will be essential. But other than that, the cycle of renewable generation to electrolysis to hydrogen-powered generation to electricity on the grid is, at best, mid-40s% efficient, currently mid-20s% and realistically achievable mid-30s%. And the total electrolysis storage and generation equipment required for this is costlier than our 68-70% efficient Green CAES, which I therefore believe is better for those applications. Hydrogen has different applications for which it’s best.

What are those?

Hydrogen is perfect for the gas grid: up to 10-15% mix in the natural gas can be achieved with minimal modifications and upgrades. Beyond that, it’s inappropriate until you hit 100%. That’s because a mix is only useful where it’s being burned, and the applications for which hydrogen is best suited need 100% purity, such as fuel cells, transportation, fuel and chemical synthesis, iron smelting, steel works and so on.

So how would the grids make the jump from 15% hydrogen to 100%?

By creating hydrogen-industry hubs, in which hydrogen is both produced and used in bulk. This incidentally will also minimise the costs and need for hydrogen storage.  Within the hydrogen hub it’s piped at 100% concentration, isolated from the general gas grid which is at up to 10-15%. Then these hubs can grow to neighbouring areas, eventually merging to include the entire grid. Hydrogen producers can use the grid as the “swing demand”, taking all their surplus output until they can pipe it to users of pure hydrogen; they’d switch to doing so, and other producers can take their place. This will greatly accelerate the hydrogen transition.

Currently the gas system has lots of storage: will the hydrogen economy need it also? And if so, how?

Yes, it will need as much storage per unit of demand as the gas grid, though I believe that the hydrogen economy will need about half the demand. That’s because I believe that the electric economy will grow and partially supplant it, such as by heat pumps. But that still needs a fantastic amount of bulk storage, and even more so as the energy density of hydrogen is about two-thirds that of methane. And the only way currently available to store hydrogen in such massive quantities is in salt caverns just like those in which we’ll (at least initially) be storing our air for the Compressed Air Energy Storage. Therefore the hydrogen can be stored in adjacent caverns, making integrated projects even more efficient and cost-effective.

And will the hydrogen economy be powered by renewables?

Yes, but not in the way that many think. Lots of people suggest using electrolysis to take out the intermittency of renewable generation, but electrolysis – and most hydrogen-using technologies – hate intermittency which reduces their efficiency and plant life while multiplying the investment needed many-fold. For example, assuming ho hit to efficiency from intermittency, you need 2.5 times as many electrolysers if powered by 40% load-factor offshore wind than if powered by baseload electricity; three times more for 1/3 load-factor onshore wind; and six times more for 1/6 load factor solar. So using our Green CAES to remove the intermittency before it hits the electrolysers and other plants is extremely cost-effective as well as enhancing efficiency and plant life. And the more integrated the local hydrogen-related industry is, the more efficient and cost-effective the whole lot will be.

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