Low-tech Magazine

Boat mills: water powered, floating factories

The waterwheel was seen as the most important power source in the world, from the Middle Ages to the end of the nineteenth century. When smaller streams became saturated, medieval engineers turned their attention to larger rivers, eventually leading to the development of the hydropower dams that still exists today. Lesser known are the intermediate steps toward that technology: boat mills, bridge mills and hanging mills. Boat mills had already appeared in 6th century Italy and spread all over the world. Most of them remained in use up until the end of the 1800s, with some of them surviving well into the 1900s.

Trolley canal boats

For many centuries, canal boats were propelled by men, horses or mules on the towpath beside the water. Before diesel power took over, engineers developed several interesting methods powered by electricity: trolleyboats, floating funiculars and electric mules. Many of these ecological solutions could be applied today instead of diesel engines. Because of the very low energy requirements, they could easily be powered by renewable energy, generated on the spot by water turbines located at sluices. One trolleyboat line is still in use.

Fighting marine debris: the dustcarts of the sea

Considering that the oceans hold more garbage than fish by now, this might be the right time to retrain our fishermen and let them hunt for litter. Several companies offer equipment to fish garbage out of rivers, lakes and harbours. They say they could build larger dustcarts for seas and oceans, too. Send the bill to the disposables industry - and let the cleanup begin.

Sailing at the touch of a button

Lloyd Alter at Treehugger talks about our article on cargo ships and wonders if it is time for a new age of sail. One reader comments that sailing boats require a much larger crew than today's cargo vessels, which would make a comeback of wind power unrealistic. Maybe, but these days, sailing boats can also be controlled by computers instead of sailors.

Cargo ships, then and now

On an early afternoon last month, the Eugen Maersk (the world's longest ocean freighter at 1,300 feet) has left Rotterdam, the Netherlands, on the tail end of a journey from Shanghai. But the giant freighter is cruising at 10 knots, well shy of her 26-knot top speed. At about half speed, fuel consumption drops to 100-150 tons of fuel a day from 350 tons, saving as much as $5,000 an hour.

The German Preussen (picture above), the largest sailing ship ever built, was launched in 1902 and travelled mainly between Hamburg (Germany) and Iquique (Chile). It was rammed by a large steam vessel in 1910. A one way trip between Germany and Chile took the cargo vessel between 58 and 79 days. The best average speed over a one way trip was 13.7 knots. The lowest average speed was 10 knots.

One giant container ship can emit almost the same amount of cancer and asthma-causing chemicals as 50 million cars, study finds. Time for a new age of sail.

Picture credit.

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The age of speed: how to reduce global fuel consumption by 75 percent

If we cut the average speed of all vehicles by half, fuel consumption would decrease by a whopping 75 percent.

Breaking speed records was an almost daily occurence throughout the 20th century. Cars, ships, planes and trains became faster and faster, year after year. Because the power needed to push an object through air increases with the cube of velocity, this race to ever higher speeds raises energy consumption exponentially.

Engineers treat velocity as a non-variable, while in fact it is the most powerful factor to save a really huge amount of energy - with just one stroke, at minimal cost, and without the need for new technology. Lower speeds combined with more energy efficient engines, better aerodynamics and lighter materials could make fuel savings even larger.                                                                     Picture : Mando Maniac

Life without airplanes: from London to New York in 3 days and 12 hours

Flying has become cheaper than taking a train or driving a car. Yet, environmental concerns, dwindling fuel reserves and fast rising kerosene prices are threatening to turn airline travel into a privilege for the rich again. This should not mean the end of mass travel or tourism, however.

Before mass air travel took off in the 1960s, people crossed the globe in majestic passenger ships. Reintroducing ocean liners would be more than a nostalgic move: it could be a much more energy efficient (yet slower) way to travel.

Satellite navigation in the 18th century

More than two centuries ago, it was possible to very accurately pinpoint your position on earth by means of 'satellites'.

Man has navigated across the globe by means of satellites for thousands of years – however, until the mid twentieth century, these were not GPS-satellites, but stars. In reality, the sun and the stars aren’t satellites of the Earth, but celestial navigation is based on a precopernican world view (the earth was believed to be the centre of the universe). This may sound a little outdated, but this system was perfected to such an extent that in the second half of the eighteenth century it was almost as accurate as the present-day GPS. Moreover, it was much more robust.

Picture sextant : Peter Ifland

The revival of the sailing ship

Considering the wind as an extra source of power, the fuel use of cargo ships can be reduced substantially.

Steam power and diesel engines relegated cargo sailing ships to the history books, since motorized ships are a lot faster, cheaper and more reliable. But now that the fuel use of ships and the ecological damage involved passes all bounds, there is a renewed interest in wind power as an extra source of energy; thanks to an extreme water sport.