Do we really need an electricity grid?

Electricity generation is being increasingly localised and a large electricity grid wastes energy in transmission over distance - so do we need a national electricity grid?

Do we really need an electricity grid?

To avoid suspense my answer is YES, but not necessarily the one we have at present.

Let’s consider the national grid we have. It has developed since 1926 when Parliament created the Central Electricity Generating Board with the objective of taking power generated from a few very large power stations (something like 180 or so[1]) to just about every building in the UK. It is therefore designed to flow electricity in basically one direction from the Power Station to the end-user. Unfortunately, we’re probably at a “Tipping Point”[2] where generation is increasingly diverse with many small scale generators coming on line as a result of initiatives like “Feed in Tariffs”. As well as PhotoVoltaics (now on many roofs), various sizes of Wind Turbine from less than a kW to 10MW or more and small scale Hydroelectric Power, this would include Combined Heat and Power systems and things like Energy from Waste, Tidal Power and Anaerobic Digesters. All of which will help reduce the net carbon emissions from the UK and help in the fight against climate change.

So now we need to move power from a lot of places to a lot of other places and the grid we have simply isn’t built for it. To add to that the amount generated at any instant is now much less predictable than when generation was centralised.

Add to that a demand profile that is changing – imagine what would happen when a street full of electric cars all come on charge as electricity drops to cheap rate (yes they should have been using personal rooftop PV’s but they may not be available when needed…).

Clearly if we are to continue with this system a lot of capital will need to be invested to rebuild the hardware to fulfil this changed purpose. So this has caused people to doubt if we need a grid or if a series of mini-grids (or even micro-grids) would be better. There is logic as that would reduce distribution losses (another way of saying “energy wastage”) and possibly require less investment but it is flawed in my opinion.

Let us consider the “mini-grid” of the area I was born in – The English West Midlands – (the area I live in is better in some respects but worse in others for the argument after all it has major rivers and a port). There is a population of something like 3 million people contained within an area of something like 500 square miles – a nice area for a mini-grid. Let’s assume that we put Photovoltaics on enough rooftops and squeeze in enough wind turbines to cover the maximum demand (there are some rivers but they’re not that large – they even had to dam valleys in Wales to get enough drinking water for everyone). Enough battery and other storage can be installed to cover the overnight shortfall from the failure of the Photovoltaics to generate in darkness (and the extra demand at that time for lighting). So under “normal” conditions the area is self-sufficient and stable in energy terms, maybe even able to support other areas when conditions are suitable.

So let’s look at the area in the middle of winter.  The whole of the area can easily be covered by the same weather system so typically we could expect that Snow could cover the whole area -so lots of the PV’s go out of operation completely because light doesn’t pass well through a layer of snow and ice, It’s almost dark all the time so the others aren’t producing much electricity.

Either the air is still or it is so windy that the wind turbines have “feathered out” to protect them from damage – so there is nothing there.

So we have little generation within the area. Demand for electricity is high because it now provides both heating and lighting for most of the buildings (the gas system has gone to help decarbonise the UK). So how long will the storage last? A day? A week? A month? None of them are unreasonable periods for a period of stable weather and remember if there are breaks in the weather will conditions be good enough to satisfy current demand AND recharge the storage? So the area will need to import from somewhere if essential power is to be maintained (I wouldn’t want Hospital patients to die through a snowstorm for example). But how far away will that need to be? Possibly renewable generation may be limited by the weather for some considerable distance around our mini-grid.

If we retain some fossil fuel generation to cover this sort of situation we should sensibly (if we are to obtain zero carbon emissions as we will need to) obtain this from a few very large units where we can capture the Carbon Dioxide generated and insert it into storage (something like depleted oil wells -which are mostly under the ocean). To build small units each with the expensive CCS system would almost certainly be uneconomic as without the economy of scale the costs would be ridiculous. Sensibly these units should have a coastal location to minimise the distance we need to move the captured gas.

Alternatively, we could use Biomass generation – that needs ideally to be near the source of the fuel, either near a forest or the coast (so you can import it from overseas – and you might want to practice CCS and thereby actually reduce atmospheric carbon over time so coastal location is probable as well).

Nuclear Power Stations are also normally built on the coast (often away from population centres) so the sea can provide cooling if needed.

As Birmingham is close to 70 miles from the nearest coast we’re beginning to talk about the generation being some distance away.

The other obvious source of controllable non-polluting “power on demand” is Hydroelectric. As that has geographic constraints and/or requires the flooding of valleys that is also not likely to be possible in the Midlands.

So we are likely to need to move the electricity some considerable distance (probably a hundred miles or so). So how do we move that energy around? Sounds like a National grid to me only designed to move energy in many directions.

[1] 181 listed in the National Grid 2005 Annual Statement – things have changed since with the closure of coal fired Power Stations but the grid was built on that basis.

[2] The title of a lecture by Ian Marchand at Durham Energy Institute March 2016 – my thanks to him for making me think about the subject

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