Our electricity is brought to us courtesy of the National Grid and the District Network Operators via a supply arrangement that feeds electrical power from the generators to our homes and businesses (the brilliant Carbon Co-op have done a helpful video explaining the basics of how this works). First however, we have to generate that power…
The picture of how we generate and supply electricity in this country is actually pretty complicated. Many large generators are managed via a nerve centre in the National Grid offices to balance supply and demand: a steady 24/7 baseload is provided by nuclear power stations as they are effectively impossible to quickly modulate with demand; instead gas-fired power stations ramp up and down to manage the changes in demand through the working day; some pumped hydroelectric power stations can be brought on-stream in a matter of seconds to cope with transient spikes in demand, for example the ad-breaks in popular TV shows where people pop out to put the kettle are notorious for putting a strain on the grid.
Of course, increasingly we are bringing renewable energy into the mix, predominantly through offshore and (to a lesser extent) onshore wind, however in the south in particular solar PV makes a substantial contribution to the supply in the sunnier months. Natural flow hydroelectric power plants generate power in Scotland and Wales and – controversially – some fossil fuel power plants have been converted to burn biomass, i.e. burning wood chip, much of which apparently comes from unsustainable sources in the States.
The UK has been phasing out coal-fired power stations – some coal generation has had a temporary stay of execution, remaining largely on standby in case the rest of the system runs out of capacity, however this week saw the closure of the final one, marking the end of a long era of coal-fired generation. In the meantime there are a number of other ‘peaking’ power stations that are kept ready to help out on a temporary basis, over twenty of which are diesel-fired.
It doesn’t end there however! Many of us now have domestic solar photovoltaic panels generating power directly into our homes; the lucky few may have their own micro wind turbines or hydro plants, all of which combine to provide what is known as distributed generation. As an aside, our District Network Operator friends (who run the regional supply networks) don’t really have much concern about what is going on with this side of things, so long as you keep things small-scale and don’t blow up the nearest substation by trying to sending all your spare renewable energy through them in the wrong direction – they wouldn’t like that at all.
In addition to what we generate in this country, we can send or receive power over the Channel, the North and Irish Seas via interconnectors – these high capacity cables introduce an enormous amount of flexibility so that we can sell excess generation capacity to the continent when the wind doth blow and the sun doth shine too much. Likewise, when the weather is in the doldrums and renewable energy is lacking, we can call on our chums over the water to sell us their spare electrons (although my suspicion is much of the electricity ends up in a long queue somewhere under the English Channel while an officious border control officer deliberates over customs paperwork).
I’m not done yet though, because it gets more complicated still… (pay attention at the back there) Not only can we generate power directly, we can do it virtually, for example by encouraging people to use less of it at certain times of day when demand is high or by storing excess power in batteries (e.g. domestic or commercial-scale batteries or even EVs) or other storage media such as liquified air that can be called drawn down when the grid is under strain. Furthermore, there is increasing interest in converting surplus power into hydrogen – a fuel that can be blended into the gas grid to reduce its carbon emissions or used to power planes and heavy-duty vehicles that do necessarily lend themselves to battery technologies.
Next time we’ll look at how these various technologies play a role in reducing carbon emissions (or not as the case may be) and how factors such as where you are in the country and what time of day and year it is play into the grid “carbon intensity”.