Sunday, 20 March 2011

Baking bread at home uses more energy

My friends rave about home-made bread (I have a gluten free diet and, whatever they may tell you, gluten free bread is never as good). I won't argue about the taste. However, if you are worried about climate change or energy security you should consider that baking bread in an oven at home typically uses much more energy baking in a factory. A study in Germany in 2003 found that a home oven uses about 3 times the energy of a factory, the difference being about 4MJ/kg bread or 1.1kWh, which means about 600g CO2/kg for an electric oven, or about 200 CO2/kg for gas. This is pretty well borne out by the measurements I took on my small gas oven at home: it took 0.4 kWh to preheat the oven and another 1.1kWh to cook for an hour - (I was baking potatoes which took a little longer than bread). Most of this energy goes into the oven and not the food, so it makes sense to cook as much as possible in one go. My small oven could only accommodate 2 small loaves so about 1kg bread. Using a breadmaker is more efficient for small batches: my friend's machine uses 0.3kWh for a 300g loaf.

Using organic flour saves some energy because wheat needs a lot of fertiliser and chemical fertiliser needs a lot of energy. Howeve the difference is only about 0.25kWh/kg.
If you want to be as efficient as possible, be sure to bake as much at once as you sensibly can, or use a breadmaker for small quantities.

Source: Life cycle analysis of bread production, G.A. Reinhardt, J. Braschkat, A. Patyk & M. Quirin (Institute for Energy and Environmental Research Heidelberg): 2003

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