Sunday, 17 June 2012
We can do just that: stretch our oil use, decrease our involvement in the Middle East, reduce climate change, dramatically lower the number of traffic deaths, extend the life of our cars and increase neighbourhood safety all at once. It’s called driving slowly.
Strangely, though, this simple method gets very little attention, and the reduction of the 55-mile-an-hour limit in the USA was unpopular and short-lived. Most drivers assume they not only can, but should hurtle towards their destination at dangerous speeds that devour fuel and money – not only at the high speed limit, but 9.5 miles over it. But the higher your speed, beyond a certain point, the more fuel you use per distance travelled.
As Kris DeDecker described in Low-Tech magazine, “[a]ir resistance (drag) increases with the square of speed, and therefore the power needed to push an object through air increases with the cube of the velocity … If a car cruising on the highway at 80 km/h requires 30 kilowatts to overcome air drag, that same car will require 240 kilowatts at a speed of 160 km/h … Thus, a vehicle needs eight times the engine power to reach twice the speed. In principle, this means that fuel consumption will increase fourfold (not eightfold, because the faster vehicle exerts the power only over half the time).”
In other words, travelling half as fast could save you up to 75 percent in fuel costs. Since 60 percent of the world’s oil is used for transportation, if everyone cut their speed in half tomorrow, this would reduce world oil consumption by about 45 percent. Obviously this is theoretical and everyone won’t act at once, but it reminds us that the simplest solutions are often the best.
Such a simple equation inevitably has many complications, but none that are fatal to the basic idea. DeDecker does note that today’s cars are unfortunately designed to be maximally efficient at higher speeds, which reduces the 75-percent figure somewhat unless the engines are adjusted – and, in fact, most automotive sources say the best speed is between 50 and 80 km/hr (35-55 miles/hr). It also doesn’t allow for urban congestion and frequent stops – although slower speeds would discourage the unnecessary trips that cause congestion, and make bicycles and taking public transportation a more cost-effective option.
To spread this message, Minnesota farmer Fulton Hanson is promoting an international “Drive Easy” campaign and a web site, http://greenslowmovingvehicle.squarespace.com. Hanson, a longtime community activist and grandfather, has been speaking and writing about his campaign for several years, selling stickers and car magnets through his site.
The campaign has been endorsed by the Orion Grassroots Network, Congregations Caring for Creation, Global Warming 101, Alliance for Sustainability and the Sierra Club. As Hanson says, “It’s not the only answer to climate chaos and the oil crisis, of course, but it’s a first step that everyone can do -- now, easily, with no new technology or training. We already have the grand solutions; we need to get more people to take those first steps.”
Driving more slowly would also save many lives. Researchers at the University of Adelaide found that, for every five miles of speed above 60 km/hour (40 miles/hour), the risk of a fatal accident doubles. A car travelling at 65 km/hour was twice as likely to be in a fatal car crash than one travelling at 60 km/hour. A car driving 70 km/hour is four times more likely, and so on. Driving more slowly allows you more reaction time, your car more braking time, the other car or pedestrian more reaction time and so on.
But maybe 75 percent, or whatever figure you can achieve by driving slowly, is not enough – maybe you demand an additional 500-percent increase in efficiency on top of that. There is a way to do that as well: add four more passengers to your car. Most cars on the road are bizarrely empty, but even a fully-loaded Hummer harms the world far less than a one-man Prius.
Much of the peak oil discussion focuses on ever-more-ambitious technology: how we can use better equipment next time, drill in the Arctic, squeeze oil from rock or farm it from algae. Give us a dilemma of this size, and our thoughts instantly turn to the expensive, the destructive and hypothetical – the qualities that got us here in the first place. We pay far too little attention to the most needed and immediately feasible solutions: the simple, the modest and the slow.
Drive Easy campaign: http://greenslowmovingvehicle.squarespace.com. “The age of speed: how to reduce global fuel consumption by 75 percent,”
Low-Tech Magazine http://www.lowtechmagazine.com/2008/09/speed-energy.html
“Fatal Impact – the Physics of Speeding Cars,” Australian Academy of Science. http://www.science.org.au/nova/058/058key.html
Originally published in June 2010 in the Kildare Nationalist newspaper.