Science

Sweat Perspective in a Bitcoin World

(Bitcoin numbers revised May, 2024)

Back near the turn of the century 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 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 developed a frustration with energy waste and energy show-offs, both gear and people.

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.

We were a long way from breaking our addiction to fossil fuels back then, and 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’ve proven 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.

The last quarter-century has brought some incremental progress in energy acquisition and policy. Sometimes circumstances or mother nature or even human progress can intervene on the positive side. But the ever-increasing demand for energy always seems to involve bad trade-offs for good results. It's good that U.S. dependence on foreign oil has been largely eliminated, but much of the shortfall has been offset by by fracking. 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 demand for lithium and other materials needed to make the vehicles means serious environmental and political disruption. Modern nuclear fission reactors are far safer and more efficient than reactors made fifty and more years ago, but the public fear of nuclear energy creates a seemingly unbreakable stalemate.  And scalable fusion reactors are still on the distant horizon.

And now we have the normalization of 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.) As of this writing in May, 2024, the Cambridge University Bitcoin Electricity Consumption Index estimates a demand of 18.3 gigawatts, with an annualized consumption of 161 terawatt-hours or 161 billion kilowatt-hours. For reference, the U.S. Energy Information Administration reports that utility-power generation in the U.S. produced about 4.2 trillion (4200 billion) kilowatt-hours of electricity in 2023, about 60% from fossil fuels, 21% from renewables, and 19% from nuclear power plants. So keeping bitcoin secure currently requires the equivalent of almost 3.8% of all the power generated by U.S. sources. 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 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 19.69 million bitcoins in circulation as I type. Each one is supposedly worth $63,791. The average kilowatt-hour in the U.S. today costs 16 cents, a small sum to pay for running a microwave or a vacuum cleaner for a full hour, but a  large sum to pay for just one of those 161 billion kilowatt hours needed by blockchain server farms to keep spinning those bitcoin digits forward. It's funny that they're called farms when all they produce is heat.

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

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

DL

 


Remembering Arvel Gentry and John Letcher, Pioneers of Sailing Science

It was nearly 30 years ago that Sailing World published "Fluid Dynamics: How Modern Science and Sailing Discovered Each Other." (You can read it here in PDF form.) The main players covered in it, Arvel Gentry and John Letcher, have gone to Fiddler's Green, Gentry in 2015 and Letcher in 2018. Both were geniuses and gentlemen of the sport.

Almost a quarter-century before that article appeared, Gentry had written a series of lessons in Sail magazine that debunked some of the popular concepts of how sails worked. "Gentry and company were weighing in with talk of stagnation streamlines, separation bubbles, starting vortices, Kutta Conditions. They were saying outright that much of what modern sailors had been taught about lift and drag on an airfoil was just rot. And they weren't appreciated."

They weren't appreciated because, as sailors and human beings, we tend to simplify concepts until our brains are comfortable with them. Well, as Einstein said, "Everything should be made as simple as possible, but not simpler." To this day, despite the prodigious advances in both the hardware and software that have made computational fluid dynamics (CFD) commonplace in the design of vessels, sails, and underwater appendages, there's still plenty of mystery in how these structures operate in the real world, and it's not for want of either brain power or computer power.

CFD_Shuttle
A CFD image of turbulence behind the space shuttle on re-entry. Source: Wikimedia Commons.

What aero-hydrodynamicists and computer engineers have been able to do with CFD is create an animation of dynamic events, and they can make pretty accurate predictions of how things will work given a particular set of imagined conditions. But of course fifteen degrees of heel angle are not always fifteen degrees. And real waves don't observe a constant height or frequency. Windspeed varies. Wind direction varies. The same goes for the set and drift of water current. Then add in the human factor: People steer differently, and trim sails differently, and move around the boat, changing everything all the time.

As the Fluid Dynamics article says, "The essential challenge... is in trying to make a vessel move nicely through two fluids simultaneously, part of it stuck down into thick, slow-moving water, and the other part stuck up into thin, fast-moving air. Add peripheral challenges like waves, local wind dynamics, geographical effects on both fluids, and the limitations of  boat design, and you've got an excellent puzzle to solve." Which is why people like Gentry and Letcher have always been drawn to the sport, and why sailmakers and Formula One engineers and aeronautical engineers enjoy talking to each other.

There's still mystery in sailing because the elements we sail in are always chaotic, slightly or greatly. It seems likely that there are some people who, by nature or practice or both, are better attuned to the what's coming through the chaos pipeline than the most powerful and sensitive computer program. Will that always be the case?

- DL