Electrification is the key to energy efficiency

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The writer is chair of the Energy Transitions Commission

Growing energy use has been fundamental to human progress. Since 1800, global energy consumption has increased 30 times, supporting a transformation in living standards.

Over the past 20 years, total “final energy” consumption (which measures energy at the point of use, such as in appliances or vehicles) has grown about 1.8 per cent every year, while global GDP has increased by 3.4 per cent annually. As prosperity rises still further, particularly in many developing countries, so will demand for energy-based services. Both air travel and air conditioning will probably increase by around 150 per cent by 2050; and passenger road traffic could rise by 70 per cent.

If the energy to support this growth were supplied from fossil fuels, harmful climate change would more than offset the benefits of the growth in energy-based services. But electrification would allow us to meet these demands in a zero carbon fashion while cutting energy input by a quarter.

So we have to build a new zero carbon energy system based primarily on electricity. This is now possible at low cost. In many countries, solar plus batteries can already or will soon provide round-the-clock electricity more cheaply than coal or gas; in others, wind power will be an ever more economic solution. And while in Europe and the US new nuclear plants are too costly to be competitive, much lower costs are being achieved in China, India and South Korea.

With zero carbon electricity we can eliminate emissions in end use; electric vehicles take the local pollution out of road transport. But as the Energy Transitions Commission’s latest report shows, electrification is also the key to a dramatic improvement in energy efficiency, potentially reducing global final energy demand by 24 per cent over the next 25 years, even as global GDP doubles.

Electrified applications are far more efficient than those that rely on burning fossil fuels. Internal combustion engines turn only 25 per cent of the chemical energy in gas or diesel into kinetic energy in the wheels, with 75 per cent turned into wasted heat. Electric vehicles, by contrast, use 90 per cent of energy input to drive the wheels, and waste only 10 per cent. The most efficient gas boilers can turn 90 per cent of chemical energy into heat within the home; a heat pump can produce 4 kWh of heat per 1 kWh of electricity input, making it four times more efficient than gas.

There is also potential to improve the efficiency of already electrified applications. LED bulbs use 90 per cent per cent less energy than incandescent bulbs to emit the same light; air-conditioning could be two to three times more efficient than the current average in Europe and US. Building insulation can cut the need for heat input or extraction.

An even bigger reduction of 36 per cent could be achieved in “primary energy” — that which is input before conversion losses in power plants and refineries. When electricity is generated from fossil fuels, 40-65 per cent of the input energy is lost as wasted heat. With solar, wind and hydro resources wasted heat is trivial. Opponents of action to limit climate change often claim that a transition to zero carbon energy is impossible because fossil fuels account for about 80 per cent of current energy supply. But that figure is only so high because fossil fuel use is inherently inefficient. 

The period of rapidly increasing energy productivity will not last for ever. Once almost all electricity is made without fossil fuels, and most applications are electrified, opportunities for further improvement will decline. The efficiency of electric vehicles and appliances will continue to improve but almost certainly not fast enough to offset growing energy service demand. But, for the next 25 years, rapidly increasing energy efficiency can help us reduce carbon emissions fast and at low cost to consumers.

There is no shortage of land for solar farms or of the minerals needed to support an electrified economy, but if we reduce the total investment needed in solar or wind supply, power transmission networks and nuclear plants, it will be far easier to achieve a zero-carbon economy by mid-century.

Seizing this opportunity will, in most cases, result in lower costs to consumers. EVs are far cheaper to run and will soon be cheaper to buy upfront than combustion engines. In China they already are. Heat pumps are more expensive than gas boilers, but yield significant savings in ongoing energy costs. And if buildings are constructed to high insulation standards, the additional upfront investment is small relative to the running cost savings.

Electrification provides the key not only to a future of abundant zero-carbon energy services, but to a faster and lower-cost energy transition.

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