Defence chiefs were accused today of prolonging Britain's reliance on fossil fuels as it emerged they have sought to block dozens of new wind farms.
The Ministry of Defence has submitted planning objections to 44 of the schemes over concerns they interfere with radars and obscure the vision of low-flying aircraft.
The number of developments opposed by the MoD has risen sharply over the last year, to 23 across 2007.
The scale of the MoD's opposition comes amid increasing concern about the planning obstacles to green energy schemes, voiced by figures including Business Secretary John Hutton.
The British Wind Energy Association has warned that wind farms, crucial to the UK in hitting its renewable energy targets, are being held up by the planning process.
The MoD insists that all of its objections are "absolutely essential".
But Greenpeace accused defence chiefs of holding back progress.
Senior climate campaigner Robin Oakley said: "Last week Gordon Brown made it clear that climate change presents a defining threat to our national security, so why is the MoD presenting one of the biggest challenges to ending our dependence on fossil fuels?
"If the Government is truly committed to tackling climate change then it must stop its own departments from objecting to vital new projects like wind farms.
"Britain's armed forces are respected worldwide for their problem solving ability; instead of standing in the way of progress our defence chiefs should be implementing the solutions."
Proposals which run into opposition face demands to be scaled back in terms of the height and number of turbines.
Environmentalists are concerned that attempts to increase the generation of green energy are being thwarted by planning hurdles.
The proportion of applications turned down increased last year, according to the British Wind Energy Association.
Some 44 of the projects have come up against defence chiefs over the last three years, including two so far this year.
Defence minister Derek Twigg told MPs recently: "The Ministry of Defence fully supports the Government's renewable energy policies and considers each development proposal on a case by case basis and only objects where absolutely essential.
"To assist developers and avoid unnecessary expenditure MoD operates a pre-planning consultation system.
"We are always ready to consider mitigation measures, ie changing height or number of turbines or slightly changing their location where mutually agreeable if that would allow a development to go forward."