Why the Tesla Powerwall could save millions of lives

The recent announcement of a ‘Powerwall’ by Tesla may seem as though it has little to do with development in Africa or Asia, or alleviation of poverty. At $3500 dollars per unit for what the press are calling ‘very expensive electricity’, it may seem that this high tech management of power loads within a household is far removed from the slums of Kibera in Kenya or the rural areas of Uganda that have no access. However, yesterdays announcement is actually really good news and a good step forward in a potentially new transformative story being written about cooking.

section-hero@2x20 months ago I as a researcher noticed the price trends in Solar Photovoltaics and Batteries. I projected forward to 2020, and something wonderful happened on paper…….

There are about 3 Billion people in the world who still use Biomass for cooking. Of these about 1.5 Billion spend more than $10 cash per month purchasing their fuel of charcoal or wood. This suggests that if a unit could be made that supplied enough real useful energy for cooking at say $360 (3yrs at $10 per month), then using recent innovation in service delivery business models these units could substitute for charcoal. Charcoal and wood emissions are one of the biggest killers in Africa and Asia. Acute respiratory infections are said to account for over 1.5 million premature deaths per year – more than Malaria, more than TB, and by 2030 more than HIV. Berkeley Professor Kirk Smith has been arguing to the World Health Organisation and other donors interested in this, that even with improved cooking stove emissions still kill. The only way forward is zero emissions at the point of cooking. Cooking with electricity would do this.

Does electricity as a fuel for cooking make economic sense? In simple terms – yes. A family of four will consume 1.4kWh (at the cooker) for two hot meals a day. [Of course different societies cook differently, and at this point someone will be thinking – “but Africans boil beans for four hours”. First, that’s a myth – some do but most dont, and second, we have looked at 35 recipes from Africa of typical meals and my statement is based on that research – 1.4kWh covers the majority of cooking styles. And, going back to the simmering beans, actually four hours at 180W (which is what you need to simmer with a lid), is therefore still within the statement]. $10 a month for charcoal translates into roughly 35 US cents per day, therefore anywhere that sells electricity at less than 28 cents per kWh could be used for cooking more cheaply than charcoal.

So why don’t households cook with electricity in Africa? Putting aside access to the grid for a moment, cooking with electricity in Africa is hardly found even in the capitals. In most locations in Africa, and many in Asia, even where electricity is available, people continue to cook with biomass. Why? The supply is not regular enough with load shedding being frequent. It can be found in South Africa with its regular supply, but in most African capitals recent surveys show people continue to use charcoal (unless LPG is promoted and made cost effective). In these places, the grid is under supplied and the householder cannot be sure that the supply will be there when they need it. Another reason is simply the wiring – Informal settlements have dodgy unsafe wiring, and by loading it with the 1kW needed for cooking everything might fry not just the meat.

And then there is the question of access that we put to one side. Actually the majority of households don’t have access to electricity. Large programmes of development are seeking just to get solar lights or solar home systems to substitute for kerosene lamps (also massive killers by their particulates). The idea of replacing biomass for cooking with solar seemed far-fetched.

However, this is why the Tesla announcement is a potentially significant step forward in this quest for zero emission cooking among the resource poor. Our background research showed that by 2020 we might reasonably expect solar PV to be at 30 cents a watt, and batteries to be at $250 per kWh stored (for lithium ion batteries capable of the rapid discharge required for cooking). Therefore (without shortages of silicon and lithium), a unit capable of delivering cooking could be made for under $360. Interestingly such a unit would actually potentially last more than 3 years, however we felt that resource poor households hardly thought in terms of 6 year investments, so we had to make it make economic sense with a three year horizon. Actually today you could build a system and at $10 a month for 7 years one would get payback. However by 2020 the economics will make it a ‘no brainer’.

We then realised the heart of the system was not the solar but the battery. That’s the key technical weakness but it also opens other possibilities. With a battery cooker combination, all those people accessing the grid but refraining on relying on it due to uncertain reliability, could trickle charge during the night and cook when needed. [I am crazy enough that I wanted to prove the principle, so for the last 18 months I have been trickle charging a battery and cooking with it in the evening here in UK. For twelve months I used deep cycle lead acid, but now I am on lithium ion phosphate – it can be done.]

So 20 months ago I submitted a concept note to DFID, to the Climate Change team and it was well received. They unfortunately cannot easily make small funding for investigating an innovative idea, so they made introductions to industry and CSR units. My own research on renewables through other DFID and EPSRC funded projects connects me with universities and researchers across Africa, and the idea is being shared. For instance, in Rwanda, Practical Action and Tumba college have already conducted market surveys. My point is we need research to position this – if the idea took off we might create new dependencies substituting a local charcoal industry for importation of technical equipment. The universities of Surrey and Loughborough are considering a new proposals for longer term research into the implications of this idea. Research that will anticipate regulatory importation challenges, will consider what this means in terms of behaviour change, impact on the grid if Tesla like units are produced, etc.

Anticipating the comment section – Some people who have wrestled with Solar lighting think from an energy point of view and think it’s a step too far – to them I say – think from the economic substitution of charcoal point of view. Some people who wrestle with improved cooking stoves think that from a manufacturing point of view it’s a massive shift in behaviour – to them I say – consider South Africa where electricity is a realistic option for cooking, and where it does occur in some places.

However this is why the Tesla announcement is a step forward. In its current configuration (excuse the pun), the Tesla unit is seeking a market in developed well-endowed nations. However even then it is talking about 64 cents a kWh, which is not far off the 50 cents that makes sense. And a unit for the poor wouldn’t require the sophisticated controllers they have, nor the variance of up to 350V.

The potential is there for a smaller unit which would open up cooking for the poor and save lives. The Tesla announcement ‘proves’ that Lithium Ion batteries are capable of managing energy for even a sophisticated household, and therefore a simple unit capable of cooking cannot be far away. The Tesla unit positions itself as potentially able to ‘transform our energy infrastructure?’ The trend it points to and a simpler version could by 2020 stimulate a transformation of the way the poor cook, saving them money, saving the local environment, saving their lives.


  1. […] Source: Why the Tesla Powerwall could save millions of lives | Solar Electric Cooking […]


  2. […] can make the household access ‘reliable’.  In other places I have drawn attention to Tesla Powerwall, and in the ACE paper (Draft available) I show how reliability by energy storage is more cost […]


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