BoatSense

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.

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).

DL

 

Remembering Arvel Gentry and John Letcher, Pioneers of Sailing Science

It was a quarter-century 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.

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