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ISIS Report 30/09/09
The Community Cooker Turns Rags to Riches
An extraordinary recycling project turns rubbish into energy and potentially
transforms slums into resource rich communities Sam
Burcher
A fully illustrated
and referenced version of this paper is posted on ISIS members’ website.
Details here
The full report can also be downloaded here
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The disturbing scenes of human deprivation in the highly
acclaimed movies Slum Dog Millionaire and The Constant Gardener [1] show the
real-life slums in India and Africa overflowing
with people and with refuse. But what if the piles of stinking rubbish could be
converted into what urban slums need most
of all: hot water for washing, pure water for drinking
and heat for cooking?
Nairobi-born architect Jim Archer has designed and implemented with the help of his Kenyan fellow Director Mumo Musuva and
their Planning Systems Services team the 2008 World Architecture Festival
(WAF) award-winning project in Kibera, Africa’s largest
slum, which does just that. The locals in the Laini Saba district in Kibera
have been instrumental to the success of the project they call the “Jiko ya
Jamii,” that translates from Swahili into the “Community Cooker”.
Agnes Aringo is a caterer at Jim’s architectural firm in Nairobi. She works on
the community cooker and reports [2] that the cooker is versatile,
and that it boils water, cooks vegetables, stews beef, bakes cakes, fries
food, and can be used to prepare breakfast, lunch and dinner, and make cups
of tea. The two ovens cook cakes very quickly and each is large enough to
grill a whole goat. You can’t tell that the fuel used to cook this food is
the waste products from the slum. Agnes says, “Nothing is thrown away or should
be thrown away in our environment.”
The community cooker in use
A community-led cooker
The slum dwellers themselves have solved several of the
practical problems presented by the cooker project. Volunteers from various
local youth groups collect, sort
and store the garbage in metal racks adjacent to the cooker where
it can dry. Materials that cannot be burnt such as rubber and glass are put
to one side. Biodegradable
scraps that fall through become compost manure [3].
The really useful solid waste materials like
paper and plastic – bags, drinks bottles and packaging - and food scraps from banana, cassava, maize cob
and sugarcane peel, sawdust and even the discarded carrier bags of human and
animal excrement colloquially known as ‘flying toilets’ are forked up to the
top level of the racks ready for incineration. All these items would normally
be left to rot in the street, thrown into water
courses, or dumped in local rivers.
At first, Jim was baffled as how to reward the sorters for
their time and effort. “It’s very simple,” they said. “We will do the sorting
for the public from say 6 am until midnight. But from midnight
until 6am we will work the cooker for ourselves. We will make bread
and we will bake buns and we will heat water. We will sell these and that’s
how we will make our money.” From that moment on, Jim knew they had a working
project.
Two simple taps are the only moving controls on the cooker,
which has deliberately been kept very, very simple to operate and to maintain.
One tap controls a drip flow of recycled sump oil (dirty and discarded oil
from vehicles) and one tap controls a drip flow of
water. A drop of each falls in equal amounts onto a heated steel plate at the face of the firebox, where the water vaporises into hydrogen
and oxygen, which causes a combustive reaction with the flames and increases
the temperature. As the firebox gets hotter it heats the network of steel
pipes that pass around the cooker. This resourceful technical innovation was
the idea of a local man and self-taught furnace builder Francis Gwehonah,
who has helped double the firebox temperature from 300oC
to 600 ˚C.
How the community cooker cooks
The cooker is made entirely of welded steel and has eight
circular hotplates on the top. This is similar to a ‘traditional’ hob design
except that the big metal cooking pots can be partially submerged into the
hotplates to gain and retain heat from the firebox
below. Hot food is served directly from the saucepans, or can be taken back
home by the person who has collected rubbish, or purchased a token to exchange
for cooking time. The cooker has two ovens under the hob, one either side
of the firebox.
A tall and narrow chimney rises out of the firebox between
the hotplates and reaches high above the slum. White vapour emerges like papal
smoke wafting away the almost odourless fumes from the spotlessly clean kitchen area.
Sliding down below the hob, a wide metal chute feeds a constant supply of
rubbish from the storage racks into the firebox’s hungry flames.
In theory, the community cooker should be operated 24 hours
a day providing there are people to collect, sort and burn rubbish. A by-product
of the incinerator-like cooking process is the relatively small amount of
ash that collects beneath the firebox which it is hoped will undergo a second
transformation into material to reduce fly menace in pit latrines and the
smell from open sewers, once toxic levels of the ash have been tested and
if found acceptable.
Hot water for washing
It costs Sh5 (5 Kenyan shillings, about US$ 0.06) to use the cooker to make a family
meal. A local woman Elizabeth Mumbi reckons it’s a bargain. She says [4], “I come here quite often, I find cooking
at this communal place quite cost cutting. The Sh5
I pay to use the communal “jiko” is nothing. Imagine how little kerosene
or charcoal this money can buy. Nothing costs this little any more.”
The cooker heats up water for washing which can be taken to
a communal bathroom known as a “bafu”. Four large water filled tanks are
connected by pipes to each corner of the cooker roof. They act as a reservoir
for up to 160 gallons of water at any one time. On average 50 people a day
take hot water into the bafu closet, while as many as 200 people could wash
from the rain water stored in the tanks.
Since the Laini Saba community cooker became operational in
2007, Jim Archer has drawn up plans to continue to improve the social and
environmental conditions in Kibera further [5]. He wants to
increase the number of cookers to one per every 50-70 households, which can
contain as many as 20 members per household. Jim is planning to recycle waste
water from bafu closets to flush through the open pit latrines that often
block and overflow which are to be redesigned as “aqua privies”. The runoff
from the “aqua privies” can then be bio-digested and the resulting matter
and moisture gravity fed to support the growth of vegetables, fruit trees
and shrubs to create green spaces within the slum.
In this system, waste from one activity is simply a precious
resource for another. By recycling the flow of wastes in the environment,
the levels of water consumption, ground pollution, fly and mosquito breeding
grounds and disease are all reduced.
Kibera as it is and as it could be with planning
UNEP funds cooker project
The United Nations Environment Programme (UNEP) is a major supporter of the
Community Cooker initiative and has stumped up $10 000 towards its installation.
The project is part of the Nairobi River Basin Programme (NRBP) [6], designed
to rehabilitate and restore the Nairobi rivers ecosystems to improve livelihoods
and enhance biodiversity. UNEP and the Kenyan based Paint Manufacturers BASCO
who have also generously contributed to the construction of the prototype are
keen to fund more cookers around the slum, which has a population of well over
800 000 [7]. Jim’s team has made the World Health Organization’s 800°C minimum
temperature requirement for incinerators in the Developing World their bench
mark for operational acceptability within the cooker’s fire box.
Until the current temperature
of 600 ˚C is increased a further 200 ˚C the
rubbish will continue to pile up and the majority of people in Kibera at least
will go without basic sanitation. However, Jim Archer is confident his team
can raise the temperature, but until his patent pending design reaches 800°c,
he reluctantly accepts that there should be no new community cookers.
Cookers not charcoal
About 91 250 tonnes of charcoal biomass
are used for energy every year in Kenya [7]. Contributing to this are several ‘temporary’ displaced persons camps,
which permanently shelter well over 110 000 people each. Women and children
in these camps travel further and further every day to find wood and fuel
for cooking, denuding the countryside for miles around and creating
health problems for themselves from the smoke of the firewood.
Recent research findings show that black carbon (BC), the black soot resulting
from the incomplete combustion of burning fossil fuels contribute to warming
the planet 55 percent as much as CO2, and that reducing black carbon
emissions may be the quickest, cheapest way to save the climate (see [8] Black
Carbon Warms the Planet Second Only to CO2, SiS
44). Community cookers will contribute a great deal to reducing BC emissions,
and hence earn carbon credits if BC reduction is included in the Clean Development
Mechanism of the Kyoto Protocol.
The German aid agency GTZ
has expressed an interest in placing community cookers into the refugee camps
they manage and Jim reckons that each camp would need a thousand cookers to
sustain their populations. He believes that the money that could be earned
through carbon credits from these cookers could be reinvested into a massive
reforestation project of native trees undertaken by the refugees themselves.
An engineering company in
the UK has offered to loan Jim the sensitive equipment he needs to establish
much more precisely how much carbon is emitted from the community cooker and
how that compares to the use of charcoal and kerosene plus the emissions from
the piles of rubbish in Kibera. The Engineering practice ARUP and an NGO
called JHPIEGO who are an affiliate of John Hopkins University, the Kenyan
Red Cross and the Centre for Sustainable Engineering in the UK, and the British
based Charity Glad’s House are also actively interested in the slum cooker
project.
Low tech is the future
There are seemingly infinite uses to which the basic concept
of the community cooker can be applied for local development. These include
kilns for clay bricks, pottery and tiles, small hot water systems for homes,
hot food and water for hospitals, schools and colleges, hotels and lodges.
However, Jim’s low tech and socially inclusive vision of change under challenging
conditions may not appeal to everyone in an increasingly complicated and technologically
driven world.
But what this relatively low cost and labour
engaging project does do is to give people something that they have never
had before, hot food and hot water on a regular basis. In addition, it demonstrates
that local solutions to specific problems such as the global scourge of plastic
and other waste can be transformed into the basic comforts necessary for human
wellbeing.
It is another example of the affordable, distributed, decentralised generation
of renewable energy that gives local communities energy autonomy, which is a
key to truly Green Energies
[9] (ISIS publication).
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There are 10 comments on this article so far. Add your comment
| Sam B Comment left 1st October 2009 11:11:43
Burning any organic matter including biomass such as wood can cause health problems, but crucially uses up finite resources. The incineration of infinite rubbish is probably marginally better than refuse left to rot in the streets and rivers as far as health and ecological problems are concerned. I am sure that there will be studies that can decide that. Of course the best solution would be energy derived from sunlight and also biogas from wastes. Until then, the WHO has issued guidelines around incineration to destroy harmful dioxins and filter systems are in place to deal with fumes. | Rory Short Comment left 1st October 2009 15:03:48
It is not clear from the article what types of waste are incinerated and as a previous commentator pointed out the incineration of plastic waste can lead to pollution problems with dioxins. That said however the intention to localise resource usage, in this case rubbish, is most exciting and commendable. | susan rigali Comment left 1st October 2009 16:04:02
Jim, Mumo and Agnes are cleaning up the slums and creating resource for a better life. Green spaces in the slum and possible areas for gardens will employ others to action. While toxins may be present through incineration, it certainly can not be worse than the depleted uranium others experience through wars. Brilliant work that needs support in order to continue improvement. It seems that the future of resource development comes from helping others instead of acquisition through destruction. | Flavio Lewgoy Comment left 1st October 2009 09:09:25
Sure the project is a good one. But it has a darkside, too. Incineration of organic matter and plastics generates many health problems through
air pollution with dioxins, particulate matter, toxic metals, etc. | Marian Weaver Comment left 8th October 2009 07:07:36
While this is a great stop-gap alternative to festering piles of trash and unsustainable use of scarce wood resources, I'd have to say that getting solar cookers into wide use should be a top priority anywhere in the world they are appropriate. Many of the places in the world currently experiencing catastrophic deforestation are also blessed with very reliable sunshine. My husband and I live in southern Arizona, with a climate not unlike the sahel, and we cook with the sun probably 300 days a year. No smoke, no emissions, no trees cut, dead easy once you get the hang of it. | marie-paule nougaret Comment left 6th October 2009 10:10:18
dioxins only come from chlorine loaded pstic (pvc) which might be banned world wide in a few decades… as weel as cadmium and other toxic metal additives to plastics.
The rest is goid clean fuel (fun).
Packaging may be the problem
and it's rather new
mpn
| dooberheim Comment left 7th October 2009 07:07:57
One other issue they may want to be careful of is the use of used motor oil in their firebox. Motor oil contains high levels of lead from bearing wear, that will volatilize and contaminate the surrounding area.
However, the benefit of safe water and good food may well outweigh that for them. In rich countries, we lose sight of how hard it is to live in the third world. People who can complain about dioxins, or lead, are usually not the ones that are complaining about not having enough to eat.
DK | cjohnson Comment left 7th October 2009 08:08:06
Burning this garbage for energy is a much better option than leaving it to rot on the streets.
When it comes to emissions such as dioxins and PAHs that people are concerned about, A steady, hot fire in an enclosed unit with a draft (supplied by a chimney) will yield fewer of these pollutants than hundreds of wood fires smoldering all day long even if waste materials are being used as fuel.
They aren't burning vinyl siding from suburban house remodels, last year's cell phone fashion trend, crusty BFR-treated couches, CCA lumber, mercury switches, NiCd batteries, and other items found in developed world garbage. | John Irvine Comment left 7th October 2009 07:07:05
Forget the burning - install a gas pilot light -use solar to heat the plate - drip in the water and presto you have hydrogen power for electricity generation... | Derek Comment left 7th October 2009 13:01:20
There is a physics problem here, though it may be left purposefully obscure to safeguard the idea (technology transfer reasons?), or the author doesn’t quite get the processes and so glossed the details, either way water does not dissociate into hydrogen and oxygen gas when heated!
In order to dissociate H2O into H2 and O2 you need to perform electrolysis, this is what all the major research at MIT, Stanford, CalTech, etc. is trying to develop in an economical way to usher in the hydrogen economy (hint: no success yet).
In all honesty I don't have access to the whole report (pay site...I know for a good cause and all) so the details should be hidden in there (let's hope). But what I think is really going on, and why the 'oil' is mentioned VERY briefly, is essentially an external diesel engine (as opposed to an internal combustion engine).
Heat is supplied by the fire; dripping diesel onto the plate wont ignite it because compression is needed, so the water vaporizing to steam (NOT dis-associating), increases the pressure in that sealed area around the fire box, and presto, a small bang, pressure and heat double the temp. of the cooking stove. No hydrogen, but maybe a nice way to get rid of waste oil.
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