Electricity Sub Station

OCH: Electricity

Robin McAlpine – 9 June 2022

Last week we covered probably the most difficult single task in delivering a proper Green New Deal for Scotland when we looked at decarbonising heating. This week is probably the easiest single thing to do – getting Scotland to zero-carbon electricity.

Scotland really does have a remarkable abundance of renewable energy options. That we can (with ease) supply all of our needs using only onshore and offshore wind is only the starting point. So if the question with heating is ‘how the hell do we do this’, the question with electricity is more like ‘wow, what are we going to do with all of this?’.

I’ll skip over the numbers here (if you want to read about giga-watt hours you can do so to your heart’s content by buying or downloading the Common Home Plan book). But here is the basics – as of about 2019 (when the book was published) we were probably about half way to having enough wind renewables installed to meet all our projected needs barring transport.

That allows for population expansion over the coming decades, increased usage as we decarbonise other sectors like heating and an additional amount of electricity for storage to ensure continuity of supply.

Then we need to look at transport. As we will see next week, a lot of transport will need to go electric to decarbonise Scotland and if all the vehicles likely to move to electric are included we end up with about the same energy requirement again, or in total roughly three times the amount that was installed in 2019.

But more wind energy has come on line since then and the (terrible) ScotWind auction shows that we have easy access to the energy we need to do this. Scotland can be more than self-sufficient on clean electricity using only onshore and offshore wind.

At this point a word on energy storage is needed. Let’s start by stating with one of the most important points – while I’m about to go on and describe some methods of energy storage, it really doesn’t matter too much what they are. Many different types of energy storage can be used in our grid. The only thing that matters is that we’re storing it.

This means that when the wind isn’t blowing there is no problem with continuity of supply because we have all the energy we need stored. It is central to Scotland’s energy security.

So how do we store electricity? Let me give you some examples. You probably know about pump-store – two reservoirs, one high up, one low down and you pump water from the bottom one to the top one when you have spare energy and then let it run down through a standard hydroelectric generating plant when you need it.

You may also know about hydrogen storage, where you use spare electricity to run a current through water, converting it to oxygen and hydrogen. You capture the hydrogen and then when you need electricity you use the hydrogen in a standard gas-fired turbine.

You possibly won’t have heard of some others. Liquid air storage involves using spare electricity to rapidly liquidise air which you then store in an underground tank. When you need electricity you simple let the air come back to ambient temperature, causing it to expand rapidly which means it can also be run through a fairly standard turbine.

And there are more esoteric approaches as well – if you have a disused mineshaft you can put a very heavy weight in it on a very strong cable. When you have spare electricity you winch the weight upwards, when you need electricity you let it fall (slowly), turning a turbine to produce electricity.

These are only some examples and there are strengths and weaknesses with each. Hydrogen isn’t particularly efficient, there is a limitation on how much can be stored in gravity-based systems like our mineshaft example, there are limited viable sites for pump store (and many are already used) and so on.

It’s why I’m personally keen on liquid air storage which is unlimited in scale and runs at something approaching 70 per cent efficiency which is pretty good. But there is a specific reason we promoted hydrogen storage in the Common Home Plan. It is less efficient than other methods but there are two reasons why it makes sense for Scotland.

The first is that efficiency is relative – the system that we have just now is psychotically inefficient, to the extent that we throw away insane amounts of electricity if it is generated at the wrong time (all those windy nights when we’re in bed). So round-trip hydrogen (create and then use it later) is currently below 50 per cent efficient. But that beats the hell out of our current zero per cent efficiency.

And there is another advantage – it would give Scotland first mover status in being a major hydrogen economy. There remains significant efficiency gains to be achieved from hydrogen and the nation which does this at scale first will be at a real market advantage. Since we’re using otherwise wasted electricity, you could argue that the efficiency rate is 100 per cent. It certainly doesn’t cost us anything to produce it once the infrastructure is in place.

You’ll note that I didn’t mention batteries at all there. Batteries will be important too, but they carry a different function. The above methods are all grid-level storage. This is how you keep overall supply matching overall demand. But this can be helped greatly if we start using localised smart grids.

These are basically electricity grids at the town and city level which ‘smooth’ their own usage partly through machine learning (learning when use peaks locally) but also by having some localised battery storage. These approaches ‘smooth’ the demand the local grid puts on the national grid, reducing peak demand on the main grid.

So that’s the basic picture. At the moment (again, a cause for some despair), Scotland behaves as if our ‘redundancy’ (where we get electricity from when the wind isn’t blowing) is the UK. We let mass dumping of electricity happen and have not invested in storage. We could have made much more progress on energy storage by now if we’re wanted to.

But what about the bigger picture? This is where it gets exciting for Scotland. Because you may note that I haven’t even mentioned marine energy, a truly massive source of power for Scotland that we have almost literally no domestic need for.

That leaves us a simple and very pleasant question – once we finally get on to deploying marine energy at scale, what are we going to do with it all?

Common Weal proposes there are three basic options. At the simplest level we can just sell it via interconnect cables (either England or the continent). But be warned, if we let that happen in a privatised form Scotland will get no benefit. There aren’t many jobs in it and the profits would just be taken by foreign corporations. Publicly-owned marine energy is an absolute essential for Scotland.

The second option is to attract energy-intensive industry. For any business which needs very large amounts of electricity, Scotland can guarantee continuity of low-cost supply. This gives us both the profit from selling the electricity and the industrial boost from what would be genuine inward investment (rather than the asset stripping which passes for inward investment just now). It is a very attractive option, but requires an activist government to make it happen.

Finally, there is the global hydrogen industry. Scotland could put the equivalent of oil rigs (we could even repurpose existing ones) to become electrolysis plants linked to subsea turbines. Hydrogen tankers could then transport that green hydrogen to markets around the world. This again has the very attractive feature of making Scotland a first mover in this market.

Like I started out with above, this is a very pleasant dilemma for Scotland. We have a highly-sought after, highly valuable resource in our air and in our sea that can equip us for great things. Right now we’re making an absolute pig’s ear of a job of developing it via a cut-price privatisation-fest which has none of the national benefits outlined above.

For Scotland to turn this around would be easy (greatly benefitted by being independent and escaping the privatisation-fest which is the UK grid). We just need a really big, future vision for how we are going to use this resource for the public good. The maths, physics and economics are a doddle.

2 thoughts on “OCH: Electricity”


    I have often wondered why the marine option of generating electricity hasn’t been fully exploited to date, especially given our natural resources in this area. I guess there has to be a major financial cost to/for private industry that has prevented this. However, my question is – “why hasn’t our Scottish Government progressed with this on a small scale, building up the basic infrastructure as it brings new marine turbines onboard? ”
    I guess I am not as up-to-date as I should be on a legislative processes regarding “whose job is it-British or Scottish parliaments.” You could eventually end up diving down a ‘rabbit hole’ researching everything haha sorry but I’ve got loadsa books to read on some weird stuff haha
    Thank you Robert for this very informative article.

    1. Robin McAlpine


      I’m on my sick bed today but I saw this and really wanted to reply. First, there are three main kinds of marine – wave (the impact of wind causing sea levels to rise and fall which releases a lot of energy), tidal (the impact of the moon dragging sea in and out, again releasing a lot of energy) and subsea (the impact of underwater current flows, particularly those that come down from the arctic towards the Azores, via Scotland’s east coast). Each has a different issue.

      Wave energy is theoretically the easiest since it’s on the surface (anything that happens under water brings problems as we shall see). Tidal is reliable but it needs quite a bit of coastal infrastructure and probably isn’t the biggest energy generator given how much of the coastline we’d be willing to sacrifice. And subsea is the golden goose, massive, permanent energy – but subsea is a hostile environment. I was amazed when I asked an engineer what was the real problem and he told me ‘pretty well 100 per cent barnacles – if you put anything that moves underwater it will soon seize up as things attach themselves to it’. If you could drop a subsea turbine and leave it indefinitely like we do with wind turbines, I suspect it would all have been done by now. I want to be careful what I write here but let’s just say that if you track where the substantial amounts of money the early Salmond administration invested in this you’ll find that far too much of it seemed to end up in the hands of equity speculators and not even nearly enough going into the science.

      There is also an ‘and then’ problem – once you’ve generated the electricity you have to bring it ashore somewhere and until now the UK Government (which controls the grid) didn’t seem interested in making the major investment to expand the grid at the point of marine energy interchanges. It’s a bit like discovering gold up a mountain that no-one can get to.

      But basically Scotland has done absolutely all of its energy exploitation through pure private sector approaches and put as simply as it can be, onshore wind is much more profitable in ratio to the capital investment than subsea at the moment. The only people currently with a very strong interest in subsea energy would be the people of Scotland generally who could benefit from it the most. That would need serious public investment and that has not been forthcoming.

      All of this will change soon. The scramble for clean energy will change the maths – subsea electricity is much cheaper than nuclear. The problem is that at the moment, when that happens, it’ll be in the hands of the oil companies. That is their strategy – wait until break-even point and then use their subsea engineering knowledge to capture the whole industry for itself.

      That’s roughly why marine hasn’t taken off. It needs a politician with the courage to take a real punt at it. But when that punt is taken it will most certainly pay off…


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