Alastair Plum finds out how consumers can change the way supermarkets work with their trolley power Weall know we should be doing a little be more for the environment but sometimes convenience stores can be, well, so convenient.

But our shopping choices affect more than what we have for dinner. Every decision, from how we travel to the shops, to what we put in our basket, has a knock-on effect on the environment.

We all need to do a weekly shop, but there are ways of making sure we do things a little greener.

The average shopping journey by car is 2.4 miles. Driving to the shops may be the quickest and easiest option but the carbon dioxide emitted on regular short journeys makes it bad news for the environment.

Find out where your nearest store, grocer or market is and try walking there.

Not only is it good exercise, but smaller retailers tend to sell more local produce, which is fresher and often cheaper than buying products sealed in plastic and flown half-way across the world.

Cycling is another good option and many supermarkets are installing bike racks to encourage this.

Think twice before buying pre-cut food. Items such as sliced carrots in a bag require more energy and more manpower to produce than buying loose carrots and preparing them yourself, which also retains more vitamins too s are better for you as well as the environment.

Excessive packaging should be avoided. As a general rule, the more complicated the packaging, the more wasteful it is.

This seems to be a message which is getting through to consumers.

Sainsbury s used to sell a pre-peeled orange. Sales were strong for the first few weeks but, after the initial high, customers backed off. As well as extra packaging, in making a sealed item without its natural protection, more additives are needed to keep the food from going off.

The major battle ground for supermarkets of late has been the plastic bag, and the statistics are astonishing - six billion bags are wasted every year.

As the major players want to be seen to be green, many are offering incentives to customers to reduce the amount of bags used.

Tesco has recently kicked off its campaign by offering clubcard points for shoppers who recycle their bags.

Somerfield, like the Co-op, has been using biodegradable bags for more than five years now.

The Republic of Ireland has charged 10p per bag since 2002 and firms in the UK have followed suit, with Ikea, Aldi and Lidl all charging customers for carriers.

Plastic bags account for 20 per cent of the nation s landfill volume, so buy a 'bag for life and keep reusing it (free replacements if they wear out).

Better yet, buy a canvas shopping bag (more and more are available, with many designers creating their own) and take that along instead.

The most important thing we need to remember is that consumer power can change the way supermarkets work.

They keep a very close eye on what is bought and what is left on the shelf.

Loyalty cards allow them to see just what you are buying, so vote with your card. If you buy more Fairtrade and environmentally-friendly products for example, they will take notice.

Here are a few more ways to make a difference if you are going to drive to the supermarket, do it with a friend to save petrol there are recycling deposit points in most of the larger stores, so take recycling with yo check where your food comes from.

Products should have country of origin details and some shops, such as Marks & Spencer, display airmile information.

If they are selling produce that could be grown or produced nearby, make sure you buy the local variety to discourage them from buying abroad and causing transport pollution.