Magma force: clean energy lights up Chiantishire

British travellers in Tuscany like to pride themselves on their appreciation of the finer things in life – the local cuisine, the scenery, the architecture and art. It all elevates their holiday status to something more than just vulgar tourism.

Now they can pat themselves on the back for taking a holiday that also has cutting-edge eco credentials. Geothermal power, an ancient energy source, is enjoying its own Italian renaissance, fuelling 25 per cent of electricity use in Tuscany. That amounts to 1.5 per cent of consumption across Italy and avoids generating an estimated 3.6 million tons of C02 a year.

The energy is a product of heat from the earth's core. The naturally occurring steam is used to to turn turbines and generate power.

A very particular set of geological conditions must be present to make this process possible and Italy is blessed with these, as well as a history of pioneering engineering techniques in the geothermal sector which makes it now the fourth-biggest generator in the world.

The traditional, picturesque town of Larderello is a two-hour drive from Pisa and the site of the world's first geothermal steam power plant. It is owned and operated by Enel, Italy's largest power group and one of the biggest in the world, with operations from West and Eastern Europe to North and South America.

It was here in 1904 that the first geothermal lights were switched on – five electric bulbs using a dynamo powered by naturally occurring steam. The construction of the geothermal plant began a year later, going live in 1913 with an initial 250KW capacity.

Larderello was the only such plant in the world until 1958, when a station was built in New Zealand. Now geothermal power generates electricity in more than 20 countries. Globally, Enel has pledged to invest €7.4bn (£3.8bn) in renewable energy between now and 2012, with €620m allocated to geothermal.

It is a strange scene. The steel pipes that criss-cross the valley like a huge metal necklace cannot be described as beautiful. But the vast grey concrete cooling towers do look oddly graceful. From time to time the gentle breeze carries the faint bad eggs whiff of hydrogen sulphide.

The science is relatively straightforward: the steel pipes take the geothermal steam from the extraction wells to the power plants, where the steam is used to generate electricity without any alteration in its natural composition. Part of the steam is then returned underground using a reinjection process and the rest is released into the atmosphere. The reinjection maintains the balance of the geothermal ecosystem.

In many of the plants, the steam is made odourless before being released into the atmosphere, thanks to a new process for reducing hydrogen sulphide emissions that was invented by Enel engineers.

In the foyer of the company's offices in Larderello, a small red rope hangs across the staircase. Our guide, Roberto Parri, the head of operations, gives us a surprising explanation: "This is to stop the tourists coming in,"

And judging by the coaches we see later in the day, it does seem this plant has become an unlikely addition to the local vineyards and olive groves as a regular tourist stop-off. The former palazzo adjoining the offices is being renovated and turned into a museum dedicated to geothermal. It is a fascinating place to visit with its unique combination of ancient power, harnessed and tamed by the magical powers of 21st-century technology.

Past the red rope and upstairs into the boardroom, we hear the company has plans for five new geothermal plants in Tuscany. Two have already been approved and three are awaiting planning authorisation.

There is a missionary zeal about the engineers and research scientists who are working on the geothermal development. They take a clear pride in this little-known part of their country's heritage. "There are 31 power plants in Tuscany and they are all remote controlled," Mr Parri explains. "A total of 459km of pipelines carry the steam out of the earth, and up to 40 per cent of the water captured from the process of extracting the steam is reinjected into the earth to keep the pressure up.

"The geological elements that have to be in place to enable geothermal power to work are a magma chamber several kilometres below the earth's surface which must be covered by an impervious layer of rock, on top of which there must be a more porous rock that allows water to pool and evaporate. Above that there must be an impermeable layer which helps to create pressure and steam."

Until the 19th century, the geothermal areas of Tuscany were uninhabitable because of the extreme heat of the steam escaping from the ground. Only then did the people realise it could be a resource. Today more than five billion kilowatt hours of electricity are generated every year for about two and a half million households. A fair number of those are rented villas favoured by the Brits.

But the biggest significance of the work lies in the global implications for the uses of geothermal energy. Enel's current operations outside Italy extend to the US, with pipelines in California, Utah and Nevada.

In Chile it has four projects in Eltatio, Apacheta, Chillan and Calabozo, at more than 4,000 metres below the earth's surface. Enel is also operating in El Salvador, Nicaragua and Guatemala. In the US alone, the company plans to double the size of its geothermal operations by 2012.

Before we leave, one of Enel's top female research scientists shows us a colour-coded geological map: one day in the not- too-distant future, the company is hoping that it might be able to start drilling in the UK.

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