LONDON, (Reuters) – The Labour government will  unveil a 2 billion pound ($3 billion) “green” investment bank in  Wednesday’s budget to help Britain’s transformation to a low  carbon economy, a government source said on Sunday.

Finance minister Alistair Darling has said there will be no  pre-election giveaways in the budget, with polling day expected  on May 6, but he wants more investment to encourage future  sources of economic growth after an 18-month recession.

The green bank, designed to help finance projects such as  railways, offshore wind power generation and eco-friendly waste  management, will be half-funded from government asset sales with  the remaining one billion pounds coming from the private sector.

“The high risk profile of these investments, which are in  new and unproven technologies means an initial government  investment is needed to draw in investors,” the source said.

“By providing an initial investment of government capital it  will reduce the risk profile for investors and increase the  incentive for the private sector to enter the market at the  scale and pace needed.”

It is estimated that Britain needs well over 150 billion  pounds to modernise its energy mix. It also has to meet climate  change targets — cutting greenhouse gas emissions by a third  and sourcing 15 percent of its energy from renewables by 2020.

The government could sell the rail franchise from London to  the tunnel linking Britain to mainland Europe, the student loan  book, a toll road crossing near London or betting company, the  Tote, to finance the investment bank, the source said.