Seeking to establish themselves as the most environmentally sound of the three main parties, the Lib Dems also pledged to end "fuel poverty" and improve public transport.
They contrasted their green policies with what they describe as the low priority given to environmental issues by Labour and the Conservatives.
And in a visit to an environmental project in London on Monday morning, leader Charles Kennedy argued that improving the environment was integral to his social justice agenda.
The party has pledged to:
The Lib Dems also repeated their commitment to creating a safe, reliable and affordable public transport system to cut traffic congestion and reduce pollution.
Charles Kennedy said: "Improving our environment improves lives and promotes social justice".
He described his party's environmental policies as "ambitious and realistic".
And dismissing the record of Labour and the Tories on the issue, Mr Kennedy said the Lib Dems were "clearly the country's greenest vote in this election."