A GREEN ELECTRIC FUTURE
A reliable energy supply has always been a prerequisite for a modern industrial society. Lenin – certainly interested in power in all its forms – once said “Communism is Soviet power plus electrification of the whole country”. In today’s world, there seems to be a move towards the second aim, although hopefully not the first.
Electrification is a large part of the proposed plan to reduce carbon dioxide emissions and mitigate future climate changes in many countries. Enthusiasts see a future where cars are battery powered and domestic gas heating systems have been replaced by electric radiators of some description, or heat pumps. As a possible route to radical decarbonisation, it has some conceptual attractions, but there are some pretty big obstacles to overcome if this vision is ever to become a reality.
Leaving aside for now the thorny issue of cost – both to the consumer and the public purse – the two major points that have to be addressed are the extra generating capacity that has to be added to the system, and the primary fuel used in the new power stations. Since the aim of the whole exercise would be to reduce carbon emissions, this point about the fuel is critical, so more about this later.
But first, how much generating capacity would be needed? The 2015 edition of the official Digest of UK Energy Statistics (DUKES) reports a total generating capacity of 85 GW in 2014, and it is this figure that is the key one in terms of meeting peak demand. Not all of this capacity is necessarily available at any one time and, in particular, the output of the increasing amount of wind and solar capacity may be out of phase with actual demand. This is one reason why the country is a net importer of electricity via its system of interconnectors to the near continent.
The same source reports a total amount of 339 TWh of electricity generated, supplemented by imports. To illustrate the difficulty of matching supply and demand, the total consumption was just 303 TWh, meaning that at least 36 TWh of electricity was either generated when it was not needed or lost in the system. To put these figures into context, the theoretical output from 85 GW of capacity running flat out every hour of the year is 744 TWh, so the overall capacity factor of the UK system in 2014 was just 45.6%.
That is what we have to supply current demand. Now let’s look at the energy used for transport and heating. Looking only at road transport (rail is a minor sector and aircraft are unlikely to go electric any time soon), energy consumption in 2014 was 40 Mtoe (million tonnes of oil equivalent), 63% used for passenger transport and 37% for freight (DECC: Energy consumption in the UK chapter 2).
On the domestic front, total consumption of fossil fuels (primarily gas) was 27 Mtoe (Energy consumption in the UK chapter 3). Interestingly, despite the historically poor standard of house insulation, total energy consumption per household has fallen significantly in recent decades, due to a combination of increased insulation and more efficient boilers and other appliances. Despite some bad publicity, energy efficiency measures seem to be at least partially successful.
What would be the impact of conversion of the transport and domestic sectors to electricity? One million tonne of oil equivalent represents 11.6 TWh of electricity. So, if we assume that overall energy consumption by all sectors remains the same, converting road transport to electricity would consume a further 464 TWh, while domestic consumption would rise by 313 TWh. Total electricity demand would be 1080 TWh, three and a half times the current total.
Actually, demand would be even higher, as a terawatt hour generated does not all reach the consumer. The DUKES 2015 report gives a figure of 27.5 TWh lost in the previous year in the high-voltage transmission system and the final distribution network; that’s about 9% of electricity generated. That would increase total demand on the generating system by a about another 70 TWh.
The energy needing to be generated for transport would also be significantly higher than the bald figures suggest. In simple terms, using a tonne of oil to power a car directly is more efficient than using it to generate electricity, distributing that to car batteries and drawing on those batteries to drive the car. Each stage of this chain incurs losses. A diesel engine can be 45% efficient. Electric motors can be much more efficient, but generating, transmission, distribution and storage losses more than offset this.
Overall, we can expect that electrification of homes and road transport would require at least four to five times the current generating capacity. However, some would argue that much of the transport load could be supplied by overnight charging. If we assume that this does in fact take care of a significant proportion of demand, then let’s be optimistic and say that UK generating capacity has to be just tripled.
Even if there were to be a crash programme to build dozens of new gas-powered stations, this would be difficult to do in a reasonable timescale and, more importantly in the context of the raison d’être of the whole project, would not decarbonise the system. There are those who say that this can be done by a massive expansion of renewable energy, but this seems barely credible. Even if sufficient sites could be found for wind farms (we have to accept that solar can only make a very modest contribution at northern European latitudes) enormous amounts of conventional backup capacity would be needed to guarantee security of supply.
The only viable alternative would be a vast expansion of nuclear capacity, which seems unlikely to happen in the near future, given the Hinkley Point C debacle. There are alternatives to the Areva design, and Small Modular Reactors could have a bright future, but we are unlikely to see any new nuclear on stream in this country before the late 2020s.
This rough analysis strongly suggests that ambitious national emissions reduction targets are going to be increasingly difficult to meet and that essentially complete decarbonisation of the economy by 2050 is currently an unrealisable vision. However, the political earthquake the UK has experienced over the last four weeks (yes, just four weeks since the referendum!) gives a golden opportunity to revisit existing policy and turn it into something realistic, achievable and worthwhile.