Choose Your Energy Source

[Hugh Janus]

Kevin Cameron has been writing about motorcycles for nearly 50 years, first for <em>Cycle magazine</em> and, since 1992, for <em>Cycle World</em>. (Robert Martin/)

It would be grand if we could just switch from fossil fuels to some wonderful alternative energy source and know we were doing The Right Thing with 100-percent certainty. But we humans, being competitive and often self-seeking creatures, know that each energy source is represented by one or more lobbying groups whose purpose is to influence investor or governmental choices in future energy policy and to present their specific version of a clean-energy future to the general public.

At the moment, one means of comparing energy production schemes that’s getting a lot of press is EROEI—Energy Return On Energy Invested. This often compares such technologies as nuclear, hydroelectric, natural gas, solar thermal, and so on. EROEI is expressed in a number that aims to give us a rough idea of how much energy we must put in, largely in the form of material-production costs, versus the total energy that we expect the system to deliver over its planned lifetime. The numbers represent a ratio: for example, if we invest one unit of energy, we can expect to get the EROEI number in return.

The resulting numbers have been something of a shock for those who have assumed that everything’s been decided rationally and that all we have to do is keep building wind- and solar-electricity generating units until they can supply (with possible battery backup) all the needs of human society.

Comparing the Numbers

Here are the ranges of EROEI numbers I have been able to find:

Power Technology	EROEI	Remarks
Nuclear	75–100
Hydroelectric	35–50
Coal (steam turbine)	30
Combined-cycle gas turbine	28
Solar thermal	9–10	Raises steam by focusing solar heat (mirrors) on a boiler
Wind	4–20
Photovoltaic	2	Conventional silicon PV solar panels

As you can imagine, there is disagreement regarding how to accurately measure the energy invested to create an electricity-producing system. For example, do we factor in crops which are no longer produced because that farmland has been covered by solar panels? It’s clear that concrete and steel used in construction are energy costs, but what about the diesel fuel burned by trains or trucks delivering materials? Shall we include a portion of the energy cost it took to build and maintain those trucks and trains? The costs of building and maintaining transportation networks? How far back up the supply chain must we look? A good PR firm is adept at adjusting such figures.

In my research, I came across one particularly interesting article on EROEI. It explained that from antiquity to near 1650, our species operated on an EROEI of up to about 5.

Moving away from fossil fuels isn’t so clear-cut. (Ubco/)

When the costs of cutting and transporting firewood to cities became too great (because all the nearby wood had been cut and burned—the low-hanging-fruit principle), a new and more energy-dense resource was developed for heating and industrial use: coal. This allowed the EROEI to rise over time to about 10. Moving forward, after 1900 when petroleum production technology matured, EROEI rose further, to about 30.

What pops out from the above figures is that by investing in substantial amounts of wind and solar, we are reversing the long-running trend to higher and higher energy returns on energy investment, and returning to numbers last seen in the 17th century.

Further Questions

Our present alternative energy policy was made during a time of relatively low energy cost. Does that policy remain correct now that energy prices have risen considerably, driven by inflation and the effects of the Russo-Ukrainian War?

How should policy be set? Strictly according to the greenhouse gas production of the various technologies? This makes nuclear, hydro, wind, and solar look very attractive, but their EROEI numbers vary widely. According to their efficiencies? A system can be highly efficient yet require excessive investment. Or should policy be set according to how much energy return we get from energy invested—the EROEI?

And of course there is another alternative, one that history tells us is often adopted: Muddling through with no clear policy at all.

Source

[Buckster]

Nuclear is the way forward.