Be Better Citizens (UK)

In a week where scientists think we’ve reached an unwelcome global tipping point, here’s something to make you think we should try harder.

OK, so this is embarrassing! I’ve been labouring under a rather large misunderstanding about global energy, the only partial salve being that almost everyone else is under the same misconception. The good news, for once, is that this is GOOD NEWS.

I’d assumed that if the world requires 100 million barrels of oil a day to run, then we need to replace all 100 million barrels worth of energy with renewables and nuclear energy, i.e. very low CO₂ alternatives. This is completely wrong, and not by a small margin. The fundamental issue is that not all sources of energy are equal. We use most fossil fuels to burn to create heat, and this is used to drive our machines, cars, power stations, foundries, etc. The practical efficiency of this process is dreadfully poor, but we don’t see it, so we don’t have any sense of it.

Let’s use personal transport as our example – cars. A small fraction of the fuel in a car can be converted into useful energy. This is not only a result of friction in the engine and other parts; it is a ‘thermodynamic’ limit imposed by ‘physics’. Cars are around 25% efficient – modern ones a little higher, in the 30% area. But most of the losses are from burning the petrol in the engine. Getting the petrol into the tank is inefficient in the first place: pulling the oil from the ground, refining it and transporting it. In the end, about 20% of the energy in the original barrel moves the car 80% is wasted, it does nothing other than make the world a little warmer (not through CO₂ and climate change, just as waste heat before we even worry about the CO₂ bit).

So, how about a virtual barrel of electrical energy generated in, say, a wind farm, used to drive an electric vehicle? There are losses throughout this process too, getting energy from the turbine into the EV’s battery, and the motors in the vehicle are not 100% efficient. Still, about 80% of our virtual barrel of electrical energy goes into moving the EV.

The summary is that the electrical energy version of this process is about 3-4 times more efficient than the fossil fuel version. Other scenarios are somewhat similar, so today, looking at the United States, about 60% of all the energy consumed in the US is COMPLETELY WASTED, with most of this waste coming from fossil fuels. In fact, the percentage of waste is dropping every year as renewables displace fossil fuels.

The overall summary across the US energy systems can be visualised in the form of a Sankey diagram. Check this out for 2023: Energy Flow Charts | Flowcharts

However, what this means is that because of the inherent far superior efficiency of electrical energy systems, we need to replace less than half of the energy from fossil fuels to continue with our energy demands exactly as we are now. It feels to me that we are twice as far along in dealing (very badly) with climate change as I thought. Perhaps we’re only f**ked rather than completely and utterly f**ked.