So in the last blog How much energy does it take to cook with electricity? I settled on 1.2kWh per day for a family of four.
This is important assumption because double the energy required (Balmer) and you double the cost – no brainer.
Arguably this is base load, and one may perhaps to prefer to design for peak load. But what is peak load? When 6 adult relatives descend for a 5 day visit? I would argue that under these conditions the charcoal stove is brought out of retirement. The literature points out that even in cases of improved stoves, people retain their old stoves for special occasions. In a standard kitchen in the West we have at least 6 devices for cooking (kettle, toaster, stove, oven, etc). Therefore it seems reasonable to design for the base load at the start and leave the peak loading to other devices – until electricity has become so common and so cheap that all cooking can be catered for (excuse the pun).
Some other random notes:-
- Much of our food here in UK is pre –processed. Pasta takes so little to cook because it has already had energy invested in it during manufacture. There are reports on how much energy it takes to cook pasta, but these are not so relevant to Africa.
- Before I found Cowan 2008, which gave me experimental real world data on how much energy a meal took to cook, I undertook my own theoretical compilation of energy requirements. I gathered all the recipes I could find for African meals from the internet. Unpacking the stated recipes into its stages ‘bring to boil’, simmer for 1 hour’ etc, I assigned energy per minute to each stage. The result was the following graph. However this is based on certain assumptions about the energy for each stage, so changing simmering from say 150W to 200Wmakes a lot of difference. Spreadsheet available.
- 150W or 200W for simmering. This actually depends on whether there is a lid for the pan or not. And this moves into behaviour change territory. The actual energy used per meal will depend on whether households can be encouraged to adopt energy efficient behaviour. The lid is the case in point! Putting a lid on simmering food makes a huge difference. Therefore I am assuming that an educational campaign is attached to any roll out of electric cooking, showing people how they can maximise the use of the energy they have (and minimise the consumption).
- Colleagues in Bangladesh and Nottingham have taken this thought one step further and have worked on insulating the immediate cooking area (not the pot per say but retaining the heat near the pot). A student project in Nottingham was able to reduce the energy required for cooking by 60% (electric heating of a pan of soup). Potentially then, the 1.2KWh could be reduced. I see this as a latter stage to any planned scaling of shifting households from biomass to electricity. I assumed we would start with a simple hot plate that would take any existing pot.
Cowan 2008 Alleviation of Poverty through the Provision of Local Energy Services APPLES (Project no. EIE-04-168) Project Deliverable No. 17: Identification and demonstration of selected energy best practices for low-income urban communities in South Africa
Balmer, M. 2007. Energy Poverty and cooking energy requirements: The forgotten issue in South African energy policy? Journal of Energy in Southern Africa, Vol, 18, No.3
Solar Electric Cooking 