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Is the solution for clean cooking solar power? Lots of new data out since this article was first posted. And more than ever the answer is: maybe, but certainly not yet, and perhaps not ever in many places. Let’s start with the basics: what's considered “clean” cooking (THREAD)
There’s a Tier system for defining what is and isn’t clean, which aligns with WHO health standards. Tier 5 is the gold standard, Tier 0 the worst. cleancookingalliance.org/technology-and… You can read about how various stoves stack up in @cleancooking‘s fantastic database catalog.cleancookstoves.org/stoves
Speaking of stacking-that’s industry lingo for using more than 1 kind of stove & it’s crucial for determining whether a solution is actually clean. If you use LPG sometimes, but mostly use a charcoal stove (you’re ‘stacking’ with charcoal), it’s the latter that determines health
This is a huge problem, because it’s easy to see an advanced cookstove in the home & think all is well, but unless it’s used *all the time* you don’t get the health benefits. Which makes sense: if you don’t smoke 18 hours a day and do smoke the rest, you’re still a smoker. 
Traditionally there have been two cooking options: LPG which is considered truly clean (albeit fossil) and biomass like sticks/ charcoal/ dung which is dirty (albeit renewable). Even “improved” charcoal cookstoves don’t reach Tier 4, which is the threshold for improving health.
(This doesn’t mean improved charcoal cookstoves aren’t cleaner, or more efficient, just that the data shows they aren’t clean enough to improve health, to be recognized as “clean” cooking.)
(And LPG is certainly clean, fast, and easy. It’s just generally not affordable to most households in developing countries without a subsidy, and there’s data emerging that points to big challenges for emerging economies that take on long term, large scale subsidy programmes. )
In recent years, many changes! The emergence of biogas, for example, as demonstrated by the great team @sisetema_bio, or wood pellet biomass gasification Fuel+Stove models like @acelesotho or ours (learn about our work and business model here: nytimes.com/2018/12/06/bus…)
These are truly clean alternatives to LPG, using renewable, locally made fuels. As in really clean. As in, virtually tied with LPG for clean news.ncsu.edu/2019/04/field-…
Being so clean yet also renewable also means these innovative solutions dramatically cut CO2 emissions, generating valuable carbon credits that can be sold to finance growth, like we’ve done with the @WorldBank worldbank.org/en/news/featur…
And perhaps best of all to the families that use them, they can cost a *lot* less than LPG to use. Because more than anything else, cost drives decision making around what a family will use. Which brings us back to where we started: the idea of using solar electric cooking.
No question, solar powered electric induction cooking is the gold standard for cooking. The fuel is free, there’s no indoor air pollution, and cooks love it. In climate/energy pioneer California, there’s even a push to switch from natural gas to electric npr.org/2019/08/05/745…
BUT (and it’s a big but) does that mean it makes sense in rural, off-grid areas? The evidence is pretty compelling: no, not now, maybe not ever. And the reason has to do with two related but separate issues: energy density, and cost.
First, density. We know it’s *possible* to use solar powered induction cookers, provided you have enough power either in the form of a massive solar photovoltaic array, or battery bank, or likely both.(not the thermal kind with mirrors which are unsuitable for a bunch of reasons)
That’s because typical induction cookers draw up to 1-2 kilowatts (1000-2000 watts) per “burner”-LOTS of power, over a long period of time. By comparison, LED solar home lighting systems require much less; typically 1-5 watts per lamp. A little solar goes a long way with LEDs
Here’s a handy comparison:learn.eartheasy.com/guides/led-lig… And for reference the “TV Deluxe” package from @fenixintl offers a 34w panel to run some small appliances fenixintl.com/wp-content/upl… . Here’s a list of typical appliance usage ( a reminder: 1,000w=1kW ) ovoenergy.com/guides/energy-…
But remember the challenge is two fold—how to first collect that amount of energy then where to store it. Then do it again the next day, and every day, even during the rainy season. For less than what those families are already paying. Which gets us to the issue of cost.
The article notes “the main barrier at present is the cost and lifetime of available batteries to provide the approximate 3kW of storage required to cook both evening and morning meals in a typical household.” That’s quite an understatement.
A 1kW solar array w/3kW of storage is a very expensive. Consider: after a contest to drive down costs for an induction system to around $155 per household, the winner cost 4-5x that ( and notes they *might* be able to get down to 2-3X in a few years). powerforall.org/index.php?cID=…
Those kinds of numbers are clearly beyond the means of households making less than $500/yr, no matter how much cleaner and easier it may be, nor the financing terms. Which means their deployment curve seems to be a long ways out from achieving meaningful scale / climate impact.
Now, the article notes a big price decline is possible. For the specialized electric pressure cooker pots, absolutely (research on that underway now by team @UKMECS) but they’ll still need all that energy, and another 90% drop in solar like the last decade seems highly unlikely.
And while research will no doubt reveal innovative ideas it’s vital to center those conversations with the end users & their traditional foods/methods. It’s just not reasonable to plan for families to switch from stewing to pressure cooking, just to make the stove work.
Even throwing massive scale at a problem may not square the circle of high cost; India’s PMUY has driven enormous new LPG connections, but even w/subsidies it’s an open question how many are refilling, and how often (see new research by @hishamzerriffi nature.com/articles/s4156…
Again, it’s worth noting that it’s hard to even pin down just how much power would be needed to deliver this kind of cooking--expert opinion varies. A lot. The folks @hivos wrote a deep dive on this in their “Beyond Fire” report. greeninclusiveenergy.org/publication/be…
@hivos Hivos estimates (pg48) a 300W system would serve one 1500W burner and cost 1275-1500€. But avoiding stacking means two-three burners, which is around 1KW of load, and triple the cost. (For reference, the @Mimi_Moto_CCFA stoves we use put out about 2,500W of energy)
Let’s now examine that--off-grid, and on grid. On a household level off-grid, you’re going to need about 10sq mt to get 1kW of power--much larger than most roofs, if they can even hold the load. Put it on the ground? Now you need to deal with shading, and securing against theft.
And don’t forget the batteries! Using this much load will deep discharge the batteries every day, dramatically shortening their life span. Which means you’ll either need more (expensive) or to replace them more often (also expensive).
Then what to do with them after? Dealing with all that lead and acid safely would require developing and instituting a massive recycling program, tough to do well anywhere, much less in communities without a tradition of it.
Let’s zoom out and look at this at on-grid level. The math, as the saying goes, is the math. A 3kW solar electric cooking system for each of the households in Rwanda would require a 900MegaWatt solar array. For reference, the national grid now has 218MW reg.rw/facts-figures/…
But even if it was big enough, it would strain any grid system to deliver all that power at the same time every day (usually right after sunset, and especially through the two annual rainy seasons) because of something called the Duck Curve.
Consider: using renewables on the world’s largest, most modern grid creates big challenges. Look at California’s demand/production as the sun goes down even as appliances fire up. You can see why the curve is named after a duck, and why it’s a problem. vox.com/2018/5/9/17336…
In Rwanda as elsewhere along the equator, the sun goes down at about same time every day, right around dinner time, meaning demand would climb as production ended. The only possible solution? Batteries--enormous, vastly expensive batteries. It’s just not realistic anytime soon.
So to say this is “quite compelling as a cooking solution for rural, remote households, which are also seeing a rapid uptake of rooftop solar and green mini-grids” creates a possibly unrealistic perception about how, for whom, and when ( or whether ) this is possible.
To sum up: cooking with electricity in off-grid areas requires systems much, much larger than any current home solar kits--an order of magnitude larger in some cases. Instead of say 50W of PV, you’re looking at 1,000W as well as secure places to put it.
And that means the financing/credit risk/access to capital commensurate to that, in a sector that's already chronically underfunded seforall.org/interventions/…, pushing #SDG7 further out of reach.
This is not to say it’s not worth discussing, but how we frame the challenges we take on is important. The choices aren’t binary, as they’ve been in the past. There are *already* truly clean, low cost, renewable cooking alternatives available.
In the end it all comes down to cost: if a cooking solution can’t reach the rural poor for less than they spend now w/out subsidies, then is it really a solution scalable to the challenge? Not all govts. are like India, with the means and will to subsidize clean energy access.
This article (by the very talented @mrcleantech) does note a lot of these concerns, and is a valuable contribution to a critical dialogue on these issues. And for on-grid customers that can afford the kit & have a strong enough grid, induction cooking offers incredible advantages
But it’s critical to be clear eyed: there are 3B people cooking with dirty, planet killing fuels. Marginal improvements (say Tier0->Tier 2) don’t deliver health/climate benefits. $$$ ones are/will likely stay out of reach. Let’s keep our eyes on the prize, and feet on the ground.
Wow, that turned into a long thread. If you got this far, thanks for reading! Hopefully it's been informative and stimulates more information exchange on this vital topic. Comments, ideas, and perspectives most welcome (/THREAD)
