Peter Lloyd is a patient man. The managing director of Mabey Bridge has waited 10 years for the right time to take the South Wales bridge-builder in a new direction.  Since 1849, the family-owned firm has been constructing bridges in Britain. It has built more than 1,000 railway bridges and worked on landmarks such as the Severn crossing.  Now, Lloyd is propelling the company into the green economy. He has staked ?38m of the firm's cash on a move into the production of huge towers for wind turbines.  It is a bold move. With public finances under pressure, the bridge-building industry is quite literally running out of road. Yet Lloyd, the managing director, believes that hitching the company's future to the green bandwagon will reap rich rewards, especially now that wind power is taking off.  He estimates the new operation, based about a mile from Mabey's Chepstow headquarters, will create about 250 jobs and support up to 800 jobs at suppliers.  It's a perfect time to switch from old industry to new. "In our minds it's not very radical," said Lloyd. "There are a lot of similarities to the bridgebuilding business. Turbine towers are made of steel plate - the same as bridges - because they have to withstand huge fatigue."  Lloyd pointed out that it will be greener to buy British-made towers - today about 90% of the towers are imported from the Continent. The market has been dominated by Danish and German suppliers.  "We are indigenous, we are bringing jobs into the community, and we use British steel," he emphasised.  Mabey Bridge buys the raw material to build the towers from the former British Steel plant at Scunthorpe, now owned by India's Tata Group.  The company appears to have taken to heart George Osborne''s message from last month's budget, when the chancellor called for the words "made in Britain" to drive the economy back to growth.  although Mabey's expansion into green energy ticks all the right boxes on the government's growth agenda, it has received no financial assistance from the state.  This is clearly something that rankles Lloyd, who approached the Welsh assembly to ask for grant funding. He was told that the company could qualify for regional development assistance only if he were to locate the factory farther west, in the former industrial heartland of south Wales. Lloyd declined because he wanted to keep the business in the Chepstow area.  Mabey Bridge's new venture is still in its infancy - it has just secured its third order. The market is gathering strength, however.  The government's renewable energy strategy states that the ambitious target of generating 15% of all Britain's energy from renewable sources by 2020 means that up to 45% of electricity will have to come from green sources. The lion's share of that is likely to be wind.  according to Renewable UK, the wind and marine power association, a 2.5 megawatt (MW) turbine located at a reasonably windy site could be expected to generate enough electricity to meet the needs of more than 1,400 households for a year, make 230m cups of tea or run a computer for 2,250 years.  The latest statistics show that the UK has 3,910MW of onshore wind power capacity - enough to power 2m homes, or 3% of total power usage.  That compares poorly with Germany, which has 23,903MW installed, equal to 7% of total energy consumption; Denmark, at 3,180MW, or 20% of total power used; and the Netherlands at 2,216MW, or 4%.  If Britain is to catch up with its European neighbours, it will have to build a lot more wind turbines.  When Lloyd first looked at the wind energy market a decade ago, he decided to keep his powder dry. Britain was slow to develop its wind power potential compared with other parts of Europe.  a few years ago, he realised that the market had firmed up, with about 400 towers erected in a year.  "There was also a reasonable view forward. Since that time we have seen a deep recession, which