During the year many of those we have interviewed and involved with improved cookstoves have acknowledged that even the best cookstoves currently available still produce emissions which affect the health of the family. There is a growing momentum towards zero emissions for household health. Our concept supports that move and could make significant improvements to health.

Linked to the goal of zero emissions is the idea that carbon finance may be available if the source of the electricity is renewable. The original concept note was predicated on a final unit price of $300, which would make clear economic sense as it tracks with monthly expenditure for households combined with a leasehold model or microfinance to overcome the initial cost barrier. During the last year we have learned that Rwanda offers subsidies and low interest loans to incentivise a biogas programme where each unit costs £900 ($1,440). While acknowledging that biogas certainly has the potential for longevity (10 years or more) which a battery/cooker would not have, nevertheless the idea that donors and government have calculated that it is worth £900 ($1,440) a unit to move people away from biomass stoves suggests that a solar electric cooking system is already financially feasible. For £900 a household could afford a cooker with a lifetime of five years, a very strong battery system and enough solar panels to comfortably meet a household’s cooking needs!

The believe that continued research will be needed in order to faciliate the development and uptake of solar electric cooking. In particular, the frame of a research proposal needs to encompass one or more of the following elements:

• Design – of a 12V deep cycle battery and hob combination. Battery lifetime needs to be investigated. Similarly, optimising the charge controller and inverter needs to be undertaken, with due consideration for harsh environments and lifetime. Such research design could also include enables M2M capabilities for monitoring of use (and potential cut off) as per the MKopa/Azuri model of service supply. The question of an inverter should not be taken as a given – the system could be designed for 12V, in which case the battery will need to be very close to the hob, in order to keep the wires as short as possible. A 12 V system might have to include hob design.

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Like all change there would be considerable socio-cultural challenges. Where electricity becomes available and affordable, the switch to electric hobs for cooking is rarely constrained by core cultural cooking preferences. The experience of heating a pan on an electric stove is fairly comparable to heating it with (a pre hot) solid fuel stove, (without the indoor air pollution). Within any population there will be some who prefer to ‘see a flame’ and ‘have greater control’ but in general there are no overarching cultural cooking barriers (as
opposed to say solar cookers which require special processes and/or a special time for cooking).

However there may be other socio-cultural challenges among resource poor communities:-

• Theft. Early adopters in particular are likely to be ‘announcing’ their equipment by the solar panel on the roof. In slums this may prove a long term problem. (By definition the panel needs to be outside and visible)
• Preventative maintenance. As a system it will likely require a very low level of technical literacy to operate. However maintenance of the battery might be a key issue. This needs to be considered in the design both of the system (prioritise safety by moving away from lead acid batteries) and the distribution network (include jobs for agents to maintain batteries monthly).
• Gender concerns. It is women who get most of the bad from solid fuels – the time taken for collection and the indoor air pollution. It is often the man of the household who makes decisions about major capital outlay or microfinance. We anticipate that there will need to be awareness raising – since it is likely that the men who control the purse strings will not see the reason why the household should make such a major outlay in order to save the woman a ‘bit of time’ and ‘clear
  away some smokiness’.
• Expectations. We have noted that the proposed system is undersized for the usual larger families found in developing countries. While suitable for smaller households (urban dwellers and refugees), it may not be appropriate for extended families cooking from a single pot. This is only a matter of sizing the system and the accompanying cost – but some research would be needed to ensure that expectations of the consumers matched the product design.

There is also a considerable environmental problem to be anticipated with the disposal of the
batteries at the end of their life.

Let us assume for the moment that a 500Watt system is suitable for small households. The final system can have other components including M2M circuitry that interfaces with a SIM card for supply of usage data for lease holding, but our simple starting point has the following components:

• Panel
• Charge controller
• Battery
• Inverter?
• Hob

It does seem that even at todays (UK) retail prices, a system with these components could be brought together. One could have the panel, controller, inverter and battery for about $350, and run a 230V hob (which would add $50) – Total $400.

Alternatively one could keep to 12V but would have to design and get built a 12V 500W hob, giving a total system cost of around $300.

These prices have been estimated from data collected in June 2013, and based on retail online prices. It therefore seems more than possible that even at todays prices, a system could be mass produced with a $250 wholesale cost (conservatively).

We started our note by aiming at the year 2020. By then with the decrease of panel prices, and by ensuring a dedicated product design, it would seem more than reasonable to think that $180 retail (including market distribution costs and profit) is a viable target price.

To those of you reading this who cook on gas or electricity, at about 2KW or more, 500W may not sound much. Certainly you can find e-discussions and blogs by campers from developed countries complaining that it is “too slow”. However as a comparison with the standard Water Boiling Test for biomass stoves, 500W will heat the smaller standard pan (2.5 Litres with lid) in 30 minutes. This compares to say a charcoal cookstove  – from cold start around 55 minutes for improved stove, and 36 minutes for traditional stove, and 35 minutes for the hot start test on the improved, and 24 minutes for the traditional stove. I.e. 500W electric is fairly comparable to a charcoal stove. But is it enough for a family cooking?

Electric cooking is much more efficient, not just from the technical side but from the control for the cooking. Control of the process is far greater than a woodfuel or charcoal stove, where turning down the heat tends to mean taking the pot partially off the stove. A 500W stove is indeed on the borderline of being able to cook for a family of 5, and we must admit that perhaps it is suitable for only 1 Billion of the three Billion from a cultural cooking point of view. Still, 500W is a reasonable starting point.

Training and awareness on the limitations of the system might be necessary and this may decrease the rate of uptake in the early stages. These factors would need to be a part of the research. If we find (as we have done) that we can build a 500W system at todays retail prices then by the time we reach 2020, and prices halve again, we should be able to build a 1KW system for a similar system price, making the limitations more than manageable.

We believe as many as 2 billion people across the developing world would stand to benefit from solar electric cooking. Who are these people? In simple terms, African and Asian dwellings can be divided into the following categories, each presenting a potential demand for a solar electric cooking solution:

• Urban dwellers in formal settlements. Many of these households may have access to electric utility. Their challenge for cooking is often that the electric supply is sometimes unreliable (with load shedding), and costly. There may be a small market within these households.
• Urban dwellers in informal settlements. These are a potentially strong market segment. Utilities often do not connect to informal settlements to avoid legitimising them. Illegal connections are often made but these are chaotic, ‘weak’ and hazardous. They are rarely strong enough to enable cooking, plus the tolerance of the utility to illegal connections is often based the fact that they consume relatively little power – if everyone started cooking, the utilities might invest more in enforcing their legal rights. The product would provide a good fit, if it were competitive with the higher grade fuels commonly used in urban areas, and it would fit urban working patterns where people eat in the evening.
• Peri-urban conurbations. Surrounding most towns is an area where connections to utilities are not really cost effective, and households need to buy solid fuels (in the absence of ‘free’ wood resources).
• Rural populations. The system is unlikely to get traction where collection of wood is relatively easy and free. Edges of forests are probably not the best market. However, in locations where fuelwood is scarce and it takes a significant amount of time to collect it, there may be a market for the system. Recent trends show access to fuelwood is decreasing in areas where it was previously abundant, and market prices are on the rise. Rural South-East and South Asia could be particularly strong markets.
• Internal displaced and Refugees. In many displacement situations refugee camps have to be provided with cooking fuel otherwise the collection of wood from a concentration of people can harm the environment permanently.

“There is an urgent need for development agendas to recognize the fundamental role that household energy plays in improving child and maternal health and fostering economic and social development.” Torres-Duque et al, 2008

Globally there has been a huge investment for more than 30 years to find a way forward. There now seem to be a myriad of possible solutions, which fall into three broad categories:

• transition to higher grade fuels (e.g. from biomass to gas)
• improved efficiency (e.g. improved cook stoves for biomass)
• solar cookers (that have varying degrees of uptake and success).

Taking these in reverse order, solar cookers have been constrained by the timing of the cooking (to coincide with the sun) and the cultural style of cooking – they work well where baking is the dominant form, but less so where other forms of cooking are the norm.

A lot of work has been done on improving biomass based stoves, including forced air, gasifiers, alternative fuels, etc. Improved cook stoves represent a promising alternative, although so far success has often been limited by  designs that are unsuitable for local customs, ineffective financing, poor distribution channels, or insufficient social marketing.

An alternative strategy is to ‘upgrade’ the fuel – to move up the energy ladder. Use of mains electricity has been adopted where it is affordable and has a measure of reliability. It is common in urban slum dwellings to find a simple electric hob or ring. However, while electric stoves are smokeless at the point of use and do not produce any emissions within a household, the actual contribution to the global environment will depend on how the mains electricity is being generated. Poor households have varying degrees of access to mains electricity, depending often on illegal connections that cannot draw too much power; supplies are also subject to load shedding and power outages implemented by the utility. As a result it is common to find kerosene and LPG gas stoves in slum areas, which, while cleaner than biomass, pose significant risks associated with fire and fumes, and also tend to be relatively expensive.

What if we could use solar cells to charge a battery during the day, and cook with it during the night, on a fairly standard cooking ring? This may not be a solution for the bottom billion, but it would perhaps address the needs of the 2 billion rising middle and upper poor.

Source: Torres-Duque, Carlos, et al.(2008), “Biomass fuels and respiratory diseases a review of the evidence.” Proceedings of the American Thoracic Society 5.5, 577-590

The purpose of this blog is to stimulate debate among actors working with policy and practice in sustainable energy. It draws attention to the 3 Billion people who continue to use solid fuel (biomass, coal or dung) for their cooking needs, and suggests that this ongoing need for clean energy might now be filled by a solar electric system. It argues that the price of solar panels, batteries and simple electric hob equipment has come down significantly over the last 18 months, and a tipping point has been reached.

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