One example is bread. I was baking bread the other day, and obviously the cost of the ingredients I put in the loaf are less than the cost of buying a loaf at the supermarket, but that doesn’t include the cost of putting the oven on.
Or dry beans vs canned beans; does the cost of boiling the beans actually bring the cost up to be equivalent to canned beans?
I know that everyone’s energy costs are different so it’s not possible for someone to do the calculations for you, but I’ve never bothered to do them for my own case because bills I get from the energy company just tell me how much I owe them for the month, not “you put the oven on for 30 minutes on the 17th of June and that cost you X”. It sounds like a headache to try calculate how much I pay for energy per meal. But if someone else has done that calculation for themselves I’d be interested to read it and see how it works out. My intuition is that, in general, it’s cheaper to make things yourself (e.g. bread or beans like above), but I couldn’t say that for sure without calculating, which as I said seems like it would be a pain in the ass.
Nowhere near, at least in a a pressure cooker. An electric pressure cooker uses 1KW when the heater is running, and you cook the beans for about 35 minutes. The heater doesn’t run the whole time but even if it did, that’s around 0.6 KWH at most. And you would normally do a bigger batch than you’d get in 1 can of beans. I have been wanting to measure the actual power usage sometime.
I don’t have a pressure cooker and cook beans on an electric stove, but I imagine it’s similar
I very highly recommend getting a pressure cooker for this. Not only is it cheaper energywise and requires less planning ahead (don’t need to soak beans beforehand, much shorter cooking time), but you don’t have to keep tabs on a pot for hours. You just pour in the beans water and salt, press a button and come back later whenever you’re ready. Especially good for Garbanzo beans, which take a ridiculous amount of time to cook on a stovetop.
On a stovetop you have to soak the beans overnight and then cook them for at least an hour, so energy usage might be higher, idk. OTOH the batch size compensates for a lot.