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April 2021

Sweat Perspective in a Bitcoin World

About twenty years ago ago I made a contraption to produce electricity from food energy — an exercise bike connected to an alternator, connected to a battery, connected to an inverter. I was editor of Practical Sailor back then, and spent a lot of time in those days with a multimeter in hand, measuring electrical current in the gear we tested. I became really interested in how much energy it takes to run things, not just aboard a boat, but anywhere, and I developed a dislike for energy waste, energy show-offs (gear and people), and lazy or gross or ill-considered uses of energy. The conclusion in that column was that we were a long way from breaking our addiction to fossil fuels. Sadly, we still are. They’re built into too much of our culture and machinery, and they’re convenient and cheap. (I mean cheap in terms of our immediate needs, not in how they relate to the state of the planet; in that case they’re proving to be very expensive.) Worse, the demand for more and more power, even with renewable energy, still overwhelms ideas of conservation, efficiency, and better design, which are more effective ways to relieve the planet. Until pursuit of these things becomes cooler than the pursuit of horsepower it will be hard to make serious headway.

Seat of Power - Doug Logan photo
There's an automotive belt from the bike's flywheel to an alternator. The gizmo provided many hours of good exercise and a clearer understanding of how much energy it takes to power things.

The last two decades have brought some incremental progress in energy acquisition and policy. Sometimes circumstances or mother nature or even human progress can intervene on the positive side. Fracking and the exploitation of natural gas deposits, for all their negative side effects, have eliminated much of the U.S. dependence on foreign oil. Public enthusiasm for electric vehicles, despite concerted push-back from fossil fuel interests, has brought about big new plans among major automakers. GM, as one example, has decided to phase out internal combustion engines and be at zero emissions by 2035: a remarkable change of policy in a massive American corporation. But the good progress often seems to have its legs cut out from under it.

There are lots of news stories these days about bitcoin. Whatever the merits or demerits may be of cryptocurrency as a means of value exchange, the computing power required by the blockchain process used to keep the system secure is massively energy-hungry. (There’s a side debate over whether it’s ultimately any more expensive than, say, mining for gold, but that’s really another issue.) The Cambridge University Bitcoin Electricity Consumption Index  at the moment estimates a demand of 14 gigawatts, with an annualized consumption of 130 terawatt-hours. For reference, the U.S. Energy Information Administration reports that utility-power generation in the U.S. produced about 4.1 trillion kilowatt-hours of electricity in 2019 (not counting about 35 billion kWh of energy produced on a smaller scale by local photovoltaic arrays and the like). That’s 4100 terawatt hours. So keeping bitcoin secure currently requires the equivalent of over 3% of all the power generated by U.S. utilities. This is not a thoughtful use of energy in today’s world.

To put it into human perspective, when you ride an exercise bike or row an ergometer or stride upon a strider at about 75-150 watts of output, you might produce the equivalent of one kilowatt-hour in several workouts, maybe a week’s worth of sweat for most of us. There are a billion kilowatt-hours in a terawatt-hour. There are 18,653,737 bitcoins in circulation as I type. Each one is supposedly worth $58,115. The average kilowatt-hour in the U.S. today costs 13 cents.

We take energy, and the fuel that makes it, very much for granted, because most of it comes to us so easily and cheaply. It’s when we see the value of energy through the veil of our own sweat that we begin to appreciate both how spoiled we are to have abundant energy sources around us, and how stupid we are when we waste so much of the stuff. 

(If you'd like to read about the contraption, it's in an editorial column called Seat of Power (PDF file).