Louisa Pearson: "My favourite delivery method is the chip buttie, made using white bread" IF YOU are looking for statistics about chips, you've come to the right place. Half a billion meals containing home-made chips are eaten in Britain each year. Friday is the most popular day of the week to eat them. For chips prepared in the home, nearly 60 per cent are oven-baked, more than a third are fried and three per cent are zapped in the microwave. My personal favourite delivery method is the chip buttie, made using white bread and liberally doused in tomato ketchup. Tomorrow marks the start of National Chip Week, a blatant publicity stunt by the potato industry, but one I had been intending to take full advantage of. Until I started thinking about the environmental impact of chips. I know, you would think I'd have better things to do with my time, but in order to live more planet-friendly lives we need to dissect and analyse the ordinary and the everyday. It may well be our collective decision whether to oven-bake or deep-fry that marks the tipping point in the fight against climate change. Of course, to make chips, we first need potatoes. It turns out that the UK is the world's 12th-biggest potato producer and the crop uses three per cent of our arable land. Britons eat more than 90kg of potatoes a year. So what's the downside? Well, lots of irrigation is required; the level of nitrates from fertilisers leaching into water courses is higher after potatoes are grown compared to cereals, sugar beet or oilseed rape, and compared to cereal crops, potatoes get higher doses of pesticides. So much to consider before we even get close to the question of salt and sauce/vinegar. Post-farming, there is the issue of storage - if you're not buying potatoes in season (April-October), they'll have been in storage, mostly likely refrigerated. The good news is that more than half of the carbon footprint of potatoes comes from the way you cook them, so we have some control. The faster the better, so the microwave gets the thumbs up (not in the taste department, unfortunately), followed by boiling, then baking. The fastest way to make chips? You're looking at 20 minutes in the oven or less than ten in the deep-fat fryer. It's one of those awkward moments when you wonder whether clogging up your arteries is worth it to save ten minutes of electricity. Chip shop chips? I haven't touched them since experiencing the worst examples ever at an Edinburgh establishment following a night of revelry. I swear the chippie must have been using the same oil for about a decade and the pale, flaccid, lukewarm chips they served could have fronted a public health campaign warning against the dangers of fatty snacks. I've been relying on oven chips to meet my needs ever since, but now feel hideously guilty when considering the mechanical peeling, cutting, part-cooking, freezing, packaging, transportation and all those other energy-guzzling steps that add to the footprint of processed foods. I tried to find something to make myself feel better on the McCain's website, and did come across the news that it has three wind turbines at its factory and an anaerobic lagoon that turns potato waste into bio-gas. So shall we be celebrating National Chip Week? Yes, because despite the environmental impact, I'm going to need something tasty to snack on while working on a new movie script: The Creature from the Anaerobic Lagoon.