Using permaculture ethics & design principles to transform an old energy guzzling bungalow into a showcase of sustainable design. It's about energy cycling, building community, self-reliance,creatively using & reusing materials... all without spending heaps of money.

Tuesday, July 29, 2014

Cooking without gas

Principle 5: Use & value renewable resources & services

We've been giving some thought to how we cook. We've been using an old gas stove for  3-4 years, in combination with our wood stove. We've run our gas stove from a 45kg bottle, and used about one bottle a year. In attempting to provide for as many of our own needs as we can we decided to replace our gas cooker with a portable electric induction cooker.

Our 50's style gas cooker running alongside our induction cooktop while we trialed them both.
According to an article I read recently, induction cookers are actually less efficient than a gas hob - but that does assume an electric grid efficiency of 40%. Being that we produce most of our own electricity with our grid interactive solar system the losses would be much less. The heat transfer loss of gas is much higher than induction, a lot of the heat goes around the pot and not into it - the induction cookers are more efficient in that area.

Boiling water preparation energy impact (kWh primary energy for 1,000 litre useful boiled water per year) for different cooking devices. Dark blue: power generation loss. Light blue: heat loss. Red: theoretical minimum. Pink: production, distribution, end-of-life. Pink: extra boiling time. Purple: standby. Green: over-filling. Source: [8].
Another factor that we have considered is where gas comes from. Increasingly, fracking is a source of gas, and is causing big problems - particularly with the contaminating of ground water supplies. As a fossil fuel, it's a limited resource that is becoming more expensive and difficult to extract from the environment.

There's also the point that gas stoves produce a considerable amount of air pollution, something that I hadn't thought about much previously. From the article Well-Tended Fires Outperform Modern Cooking Stoves:
A 2014 study estimates that 60 percent of homes in California that cook at least once a week with a gas stove can reach pollutant levels of CO, NO2 and formaldehyde that would be illegal if found outdoors. [21] The authors state that:
"If these were conditions that were outdoors the EPA (Environmental Protection Agency) would be cracking down. But since it's in people's homes, there's no regulation requiring anyone to fix it. Reducing people's exposure to pollutants from gas stoves should be a public health priority."

Our wood fired stove / oven / hot water system and heater

During the winter we run our wood stove most days. While it's not super efficient at cooking on, it does numerous other tasks at the same time - 'waste' heat, heats our home, and hot water. It's taken some time to get the hang of cooking in the oven, but we can now fairly reliably cook bread, roasts, pizzas, pastries and even cakes without burning them.


We purchased a 'smart oven' in February which replaced a 60's style compact oven that we were given that was used during the warmer months and our toaster. It's only 22lt, and so we are only heating a small space when using it and figure that it's about as efficient as you can get for a commercial electric oven. We are very happy with it. I especially like the ability to grill as we haven't been able to do that without the wood oven going.

Image of a thermal cooker, much like the one we use.

We've been using a thermal cooker, for a while. It's a specially designed pot that fits snugly into a vacuum flask, much like a thermos. The idea being that you heat up your food, insulate it and it cooks itself from the residual heat. We use it quite a lot for cooking pasta, making stock and soups.

We also have a pressure cooker that we use from time to time. It's particularly useful when cooking legumes and soups. It's cooks in far less time due to the higher temperatures of cooking under pressure.

While I'm keen to make a solar cooker, I haven't done it (well) yet. I have worked through some ideas with my mate Dylan and we might get around to it before next summer. Dylan is a glazier (amongst other things) and we've been talking up the idea of a double glazed box that sits over a pot. Solar cooking makes so much sense in summer, when you shouldn't really be cooking inside anyway - it heats up the house.

A simple rocket stove design by Mal Boyd on display in the Permaculture Victoria tent at SLF '14
I'm also keen to trial a rocket stove, but again, haven't got around it yet. The design above looks like a beauty to have a trial with.

There's some great information about some of these alternative methods of cooking in this article: If We Insulate Our Houses, Why Not Our Cooking Pots?

For another good read, you might want to check out Michael Green's article Cooking without gas

3 comments:

Dani said...

It would be interesting to know how many watts your induction cooker draws / hour.

The "Smart" oven at 2400 watts / hour would be a huge drain on our solar power!

Richard Telford said...

The induction cooker has two 'plates', one that can draw 2000w/h and another that can draw 1400w/h. So it's theoretical maximum is 3400w/h. We never use it to this extent though. For instance, when making a coffee I might have it set on 800w/h for about 5 minutes for the espresso pot, and the milk on 600w/h for 4 minutes. 67w + 40w = 107w (this is just a guess, I'll have to test it later). So in answer to your question, it depends on how much we use it.

The same goes with the 'smart' oven. The things that I like about this oven is that it's only heating a small space, so heats up quickly - with minimal energy. It has a fan / convection cooking, which takes less time to cook. It has elements that fluctuate frequently, so keeps the temperature relatively constant and only uses the energy it needs to to do that - once the space gets up to temperature it doesn't appear to use very much energy to keep it at that temperature.

What I don't like about it is that it's not well insulated (or doesn't appear to be) and only has single glazing. I'm also imagining that once the computer controls start playing up the whole thing will need to be discarded - but I guess that goes for most appliances. Unless you find creative new ways to use them.

The main thing about these gadgets is to use them sparingly, and use alternatives when it makes sense to do so. Sometimes it doesn't make sense to light the wood stove - like to make a coffee. But this might be the time that you use the rocket stove, which we haven't set up yet. There's no one answer - it really depends.

Anonymous said...

Richard,
I have an induction and am pretty happy with the electricity use. Remember that when you put the espresso pot on the ring it is much smaller than the ring (well mine is) so you are using even less than you think. If it were a normal electric, you would be wasting half the heat of the plate.