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By Noel Young
Copyright 2009
Edit International

An almost forgotten invention from 200 years ago may answer the world’s energy problems and end our reliance on oil by using the greatest source of power known to man – the sun.

It’s known as the Stirling Engine and it’s already working in satellites whizzing round the globe . . . in a collection of giant gleaming dishes trapping the desert sun in New Mexico . . . powering a tiny car noiselessly along the roads of New Hampshire. And experts expect it to bring clean water to millions across the planet.

In Britain two big companies plan to start marketing “home power plants” this spring using Stirlings which will light and heat the house, cut the homeowner’s power costs by one-third – and allow him to sell surplus power back to the electricity company.

Everyone on earth will soon know of the odd invention in 1816 by Scottish minister Robert Stirling who designed it in his church workshop by oil lamp because Edison’s electric light bulb was still 60 years in the future.

His engine came out at the same time as the highly successful steam engine which powered the industrial revolution. As the steam engine became safer and more sophisticated, interest in the Stirling engine fell away and it was largely forgotten – until now.

And that ‘now’ is breath taking.

The giant dishes in New Mexico, which focus the sun’s rays on an engine have the astonishing potential of providing the electricity for the entire United States during daylight hours.

The car, developed by America’s leading inventor Dean Kamen, is an all-electric hybrid, part-powered by a much smaller Stirling engine. He believes it can be in production in two years and show the world a dramatic way to slash the use of oil and curb carbon emissions.

Producing clean water in developing countries is another field in which the Stirling technology has already shown its worth.

Yet the Stirling is a puzzle among engines. It was largely ignored as the industrial revolution of the 19th century turned into the space race of the 20th century. But people who came in contact with it, loved it. The Stirling became a cult. Fans formed societies, who built models and attended meetings.

For much of that time, the invention was simply known as the “hot air engine..” In 1960, the Philips organization of Holland, which spent millions trying to develop it, finally dubbed it “the Stirling Engine”.

In America, Ford also spent a fortune trying to adapt it to drive a car before giving up in the 1970s.

But Stirling fans carried on. Hundreds of enthusiasts gathered last year at the Kew Gardens Steam Museum in London for a display of working models.

One household fan driven by a Stirling engine could be seen whirring away very effectively. A similar one is now available commercially from an American company, for sitting on top of a hot stove.

A Glasgow museum even has a gramophone powered by a tiny Stirling engine.

The basic Stirling is deceptively simple. Gas or air inside a completely enclosed cylinder expands as it’s heated at one end - and contracts as it is cooled at the other. This movement of the gas drives a piston, which turns a wheel outside the engine. The heat source can be anything you like.

One demonstration model, sold by the American Stirling company for around $500, (available on EBay) is driven by the heat from the palm of your hand. Whatever the size of the engine, there are absolutely NO emissions.

The big comeback started on a winter’s day in 2008 in the New Mexico desert . The sun was beating down and the temperature was zero.

At the US top secret Sandia National Laboratory, giant dishes had been built , each composed of 82 mirrors. They would catch the glare of the sun as it moved across the sky and focused the heat on a Stirling engine.

The beam of intense heat, hot enough to melt metal, started the engine pumping away, generating electricity.

By the end of that day, January 31, one of the mirror dishes had set a world record; an all-time high of 31 per cent of the energy pouring down from the sun was converted into power going into the electricity grid.

The engine used at Sandia in the SES dishes is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives pistons inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.

Chuck Andraka, lead Sandia project engineer, said the use in the Mojave desert project was “the largest proposed overall use of Stirling engines” so far. “Soon we will see these large fields of systems begin operation in the desert southwest of the US.”

Now Stirling Energy Systems, the company behind the experiment, has signed agreements with two big California electricity companies which will between them require up to 70,000 solar dish engine units. Work started on pre-production models of the mirror dishes in the Detroit area in February.

There are now two California fields already under contract; one in Imperial Valley and one in the Mojave desert. Combined eventual output will be about 1600 megawatts - about the same as a major nuclear power station. Work is scheduled to start in 2010.

An Irish company, NTR, invested $100 million becoming the biggest shareholder - and the race to really make the Stirling engine commercial has really begun.

“Just 30,000 of the dishes, in the Mojave desert, will provide enough power needed in daylight hours by the city of San Diego, with a population of 1.2 million,” said a spokeswoman for the Sandia National Laboratory. “A solar farm 100 miles square could generate enough power for the entire United States.”

But what to do when the sun goes down? One solution is pumped storage - using the daytime power to pump water to a reservoir high in the mountains - then releasing it in the evening to drive generators as it rushes back downhill.

Bruce Osborn, CEO of Stirling Energy Systems has been working to develop the engine for 25 years. “This exciting world record shows that using these dishes will be a cost-effective and environmentally friendly way of producing power,” he says. “We are now actively engaged in preparing it for mass production.”

Mass dish production will also be undertaken the Infinia company, of Washington state, which after an investment of $50 million, plans to start making 30,000 dishes this year for sale worldwide.

Company chief J.D. Sitton told me, “The Stirling engine’s moment has finally come.” Remarkably, Infinia first planned to use the Stirling engine in a fully implantable heart pump 20 years ago. “This was to be an engine driven by a piece of fully-shielded plutonium the size of your pinkie fingertip,” said Mr. Sitton.

“We had to drop the idea when it became clear that plutonium might have been attractive to people (terrorists) who didn’t necessarily have the best interests of the patient at heart.”

However, the design lived on - and grew a thousand-fold into the much larger Stirling engine at the centre of the company’s new solar dishes, which will be rolling off the production line at Infinia’s new factory any day now.

“Our first target market is Spain. It has the right climate and landscape for our dishes, “ said Mr. Sitton.

The company has also partnered with Massachusetts-based Emergence Bio Energy, to build a device for poor countries such as Bangladesh which would “co-generate” electricity and heat.

That Stirling-powered device runs on methane gas “produced by a digester that converts livestock manure and agricultural wastes into combustible biogas.” In other words, it runs on manure. In it’s first experiment two villages were successfully powered for eight hours a day.

Nowhere has the Stirling engine got its admirers more starry-eyed than in outer space.

Dick Shaltens is chief of the Power &In-Space Propulsion Division of NASA, the American space organization. He says, “I see the Stirling engine playing a major role.
I see it in deep space probes, on the planet Mars, on the lunar surface, even on asteroids , anywhere where there is insufficient solar energy to sustain a NASA mission,” He forecast. “I can see the Stirling working on a spacecraft on a 15 year mission. It is that reliable.”

A good example of the Stirling’s reliability is the Rhessi space craft, launched in 2002 to photograph the sun. It was originally a two-year mission and the Stirling’s job was to keep the instruments cool. Today, seven years later, the Rhessi is still flying - and still working!

Back down here on earth, Britain’s National Grid is about to start selling a “ home power plant” powered by a Stirling engine to replace the traditional boiler. Manufactured by Disenco of Sheffield , the heat source is gas, it looks just like an ordinary dishwasher in the kitchen, and it will cost around $5000.

But it will provide heat, light and power at savings of up to 35 per cent with a much smaller carbon footprint. And the homeowner will even be able to sell surplus power back to the electricity company.

Also planning a Stirling home power plant is the British Baxi company. The company Microgen, working with Baxi, expects a market of 150,000 of these devices over the next four years.

James Rizzo, who once ran the Maltese Ministry of Tourism took up the Stirling engine 30 years ago as a hobby. Now chairman of the British Stirling Engine Society, he says , "Most technical Universities in Japan are working on the Stirling engine as the engine of the future. The Japanese navy is now putting Stirling engines in their submarines following Sweden.

"Robert Stirling's invention may prove to be as important to the 21st century as James Watt's steam engine was to the 19th and 20th centuries."

The stranglehold that Middle Eastern oil producers now have on the rest of the world may well be loosened by the ghostly fingers of the Rev Robert Stirling, who only wanted to save his parishioners from the long ago danger of exploding steam engines. Now he can help save the world.

By Noel Young
Copyright 2009
Edit International

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