Supermarket shoppers are spending £470 a year - a sixth of their food budget - on packaging, a report suggests.
Supermarkets have been urged to cut down on packaging
The Liberal Democrats spoke to the UK's nine biggest supermarket chains about packaging, waste, and energy use.
They found customers spent £15bn on packaging each year and that delivery lorries travel the equivalent of two return trips to the moon every day.
Their How Green Is Your Supermarket? report calls for a cut in lorry trips and the use of biodegradable bags.
Environment spokesman Norman Baker said only three of the nine chains asked used railways and not enough local produce was sold.
"With one supermarket for every 10,000 people, the big chains have a duty to provide environmentally friendly alternatives, support local producers and the British organic industry and commit to saving energy.
"On sourcing, energy use and packaging, some supermarket chains are taking the lead, but that best practice needs to be shared.
His report makes 26 recommendations, including calling for:
Plastic bag recycling points at all supermarkets
"Bags for Life" on display at checkouts
Targets for increasing the percentage of packaging made from recycled material
Supermarkets to set targets for reducing lorry mileage.
Mr Baker also urged the government to encourage supermarkets to establish national standards and reach national targets on the use of local produce and making more use of rail services.