by Dr. Paul Krämer, MD tropical medicine
First published in Solar Energy for Afrika conference, Düsseldorf, 2003
Let me fist propose the core of my argument in
thesis form.
Wood is basically a renewable energy - in
principle at least. Whether this is so in practice, depends on the
maintenance of a balance between consumption and production of woody
biomass. But this balance has been upset in many countries or areas. For
this reason, renewability - or sustainability - of wood fuel resources has
to be defined in a geographical context, not in the abstract. If this
precaution is not taken, errors are unavoidable. An example of this type of
error is the country brief "Chad" [1] of the American Energy Information
Administration (EIA), where it is said that "Wood is the primary source of
total energy in Chad". The same document, however, states "fuel share of
energy consumption: oil 100 %" and "fuel share of carbon emissions: oil 100
%".
The EIA authors seem to presume that carbon
emitted from wood combustion is entirely taken up by forest stands and thus
removed from the atmosphere. But under conditions of deforestation,
degradation of forest stands and desertification this is no longer true
everywhere. In fact, a part of wood consumption varying from area to area is
not replaced by new growth and thus unsustainable.
Especially in Africa wood surfaces have declined
considerably, as ma y be seen from Fig. 2.
Figure 2:
Change of wood surfaces between 1980 and 1995, according to "Africa
Environment Outlook", UNEP 2002[3].
In most regions of the world forest surfaces
have decreased between 19980 and 1995, except in industrial countries, where
there has been an increase. This is due to the fact that they do not depend
on wood energy, and that for non-energy purposes they can rely on the
forests of non-industrialized countries. Consumption of forests as fuel does
not only increase carbon emissions, but implies also the disappearance of
vegetation and soil as a carbon sink. If we look into the change of wood
surfaces per head in Africa, the loss is even bigger: from 1.22 to 0.74
hectare/inhabitant.
Fig 3.
Consumption of biomass in Africa between 2000 and 2030, in million tons oil
equivalent (Mtoe), according to data of the "World Energy Outlook"[4],
International Energy Agency (IEA) 2002.
Biomass is still the cheapest form of energy in
Chad. This is extremely important, because 64 % of the population live below
the poverty line[5]. Each step upwards the "energy ladder" means at least a
doubling of cost.
Figure 4:
Prices of different fuels compared on the basis of equal energy content
Francs CFA per Mega-Joule, according to data from HEP/SAR, World Bank .
We see that electricity is by far the most
expensive form of energy. It is comprehensible that people avoid to use it
for energy-intensive purposes like cooking. Moreover, only less than 1 % of
the population of Chad had access to the grid in 1995.
As we have seen in figure 1, wood and charcoal
account for the bulk of cooking energy. Charcoal is becoming more and more
important because it is easier to transport than wood to urban centres and
because it produces less fume when cooking than wood. The problem is that
charcoaling is usually done with very low efficiency - of only 13 % on a
weight basis - in Chad. That means that 1 kg of wood leads to 0.13 kg of
charcoal. With improved techniques 20 % efficiency can be obtained. Under
laboratory conditions, 0.31 kg of charcoal are possible. The actual 13 %
efficiency, expressed the other way round, means that conversion from wood
of charcoal needs 7-8 kg of wood as primary energy to produce 1 kg of
charcoal. This loss is only partly compensated by the higher energy density
of charcoal, which is about double that of wood.
As we have seen, charcoal is relatively cheaply
transported over long distances, and is increasingly preferred by urban
dwellers. The annual increase in consumption in Chad is about 8 %. The
problem is compounded by quick urbanization of 7 % per year. Studies in
other countries have also shown an association between growth in charcoal
consumption and urbanization. The World Bank expects an increase in the
off-take of wood in the N'Djamena area from 410000 to 730000 tons [2]. A
internet publication of PREDAS (Programme Régional de Promotion des Énergies
Domestiques et Alternatives au Sahel)[7] puts it like this: "The
provisioning of towns and cities is the motor of the fuelwood crisis in the
Sahel" .
Fig 5.
Carbon content of wood and its split into two compartments: charcoal and
emissions. The efficiency of charcoaling in this example is 13 %, carbon
content of charcoal 90 %.
In Kenya, the production and transport of
charcoal has been made illegal, but not selling, buying and using it. Violet
Matiru and Stephen Mutimba[8] write: "Kenya's schizophrenic charcoal
policies have forced the industry underground, but the trade is too massive
to stop. The criminalization of production and transport has done nothing to
stem the growth in demand, especially in urban areas, but it has sown
fertile ground for corruption".
A study commissioned by the European Union and
the Food And Agriculture Organization of the United Nations (FAO) states[9]
: "in several (African) countries the situation of supply and demand has
reached a critical point - or approaches it - which corresponds to a
scenario, in which the poorest are deprived of their most elementary goods.
In several countries, per-head consumption is falling because of diminishing
supply and rising prices … The consumption of charcoal alters the relation
between the energetic needs of households and wood resources in the region
and transforms what had always been accepted as a way of self provisioning -
namely the collection of wood for fuel - into an infernal circle with
potentially dramatic effects on wood and forests."
Earlier attempts to disseminate solar cookers
have generally been targeted at the rural population. But the rural
population consumes less wood than townspeople, and nearly no charcoal.
Rural dwellers usually still have the possibility to collect firewood, and
they see no need to incur expenses, the more so as poverty is mainly rural.
Townspeople, on the other hand, have to buy fuel for cooking. They feel
energy prices - especially price increases - and are thus more inclined to
consider possible alternatives, like solar cookers. More often than the
rural population, the are able to invest. Attempts at dissemination of the
solar cooker technology should therefore address the urban population in the
first place, especially those families using charcoal as their preferred or
secondary energy source. This undertaking is made easier by shorter
distances and by the generally higher literacy rate in towns[10] [11].
Researchers in Burkina Faso found that the
possession of "assets" like mopeds, radios, sewing machines and so on is
inversely related to poverty[12]. Solar cookers should be presented as an
asset, with the additional advantage of making the family less vulnerable to
fuel price increases.
Figure 6:
Expected population growth rate in West Africa by sectors, based on data of
the West Africa Longterm Prospective Study (WALTPS) commissioned by
OECD/Club du Sahel: "Preparing for the Future: A Vision of West Africa in
the Year 2020"[13].
We see that the population in urban areas is
increasing about four times as quickly as in the countryside, and two times
quicker than the general population.
Sometimes it is argued in Europe that the energy
consumed during manufacturing of aluminium reflector sheets exceeds possible
energy gains in using the cooker. This is not true. The production of
aluminium needs about 48.6 Mega-Joule (13 kWh) per kg[14]. A butterfly-type
solar cooker (papillon) has about 3 kg aluminium sheets, corresponding to
140 MJ. The energy contained in 1 kg of charcoal is 31 MJ. Now let us
imagine a family of ten persons using 8.9 kg of fuel (0.89 kg/person) [15]
wood and additionally 0.5 kg charcoal per day (0.05 kg per person),
corresponding to 15.5 MJ. Then after nine days use the energy invested in
the production has been recovered by the solar cooker.
The quantity of charcoal in the above mentioned
example - 0.05 kg per person - was manufactured from 0.35 to 0.4 kg of wood
as primary energy. This latter quantity, together with the quantity of wood
used directly (0.89 kg) - minus the amount of wood that has replaced
charcoal (0.1kg) - brings the wood consumption up to 1.14 kg/person (35.65
MJ), and 11.4 kg for a family of ten.
Let us assume that in a given country or area
wood consumption as primary energy exceeds wood production by 10 %. Then it
is possible - on the basis of the above mentioned figures - to calculate the
number of solar cookers necessary to bring consumption down by 10 %. In the
case of this particular family 10 % less consumption would mean 1.15 kg
less, leaving 10.35 kg as residual consumption. These 1.15 kg of wood
(primary energy) correspond to 0.15 kg charcoal (assuming 13 % efficiency of
charcoaling), which would have to be economised by using the solar cooker.
We see that in this example the desired effect can be obtained even if the
solar cooker is used every second day. On the basis of these figures it is
possible to extrapolate to the whole population of a country or area and to
determine the number of cookers necessary[15] to obtain the targeted
reduction of wood consumption.
Experience in Burkina Faso shows, that two
workmen can make one solar cooker per day. Allowing for time off work, this
would be equivalent to 250 cookers per year. Making one hundred thousand
solar cookers would mean the creation of 800 jobs. About 30 % of the end
price represents cost of labour. Supposing a consumer price of 175 Euro - as
in Burkina Faso - the cost of labour per cooker would be 52.5 Euro, that is
26.25 Euro per workman.
As we have seen, solar cooking can contribute
not only to find a way out of the household energy crisis, but also to
contribute to solving other development problems. But solar cooking needs
active promotion. This is best done by local civil society organizations.
Cooking demonstrations are a useful means of familiarizing the population
with the handling of solar cookers.
In 1990 Kuhnke & co-workers[17] wrote. "But some
people fail to realize that, in some areas, solar cooking may soon
constitute one of the few remaining options for preparing a hot meal"[].
Solar cooking should be used, alongside other renewable energies, to solve
the household energy problems and to restore an equilibrium between wood
consumption and production, especially in countries where deforestation,
degradation and desertification are a problem.
Thesis 1: A part of the consumption of
wood energy in the Sahel is unsustainable, i.e. it is not compensated by new
growth of woody biomass.
Thesis 2: Renewability - or
sustainability - has to be proved and defined in geographical terms, i.e. in
relation to a given area or region, by comparing consumption and production
of woody biomass.
Thesis 3: Electricity as final energy - whether
produced from renewable sources or not - is not a realistic alternative for
biomass as far as cooking is concerned.
Thesis 4: Solar cookers
can help to bring wood consumption down to sustainable levels.
Limits of renewability
This contradiction may be explained by two facts:
The real role of different form of final energy
may be seen from Fig. 1:
Figure 1. Share of different forms of energy in final energy
consumption in Chad 1995, in thousand tons oil equivalent, according to data
from Household Energy Programme, Staff Appraisal Report (HEP/SAR 1998),
World Bank[2].
Effects of the overexploitation of wood
resources on the African environment
The likely increase in the consumption of biomass -
about 65 % of which are wood fuels - and the role of households in this
consumption can be seen in Fig 3.
Prices and access to energy
UNEP states in the
World Energy Outlook [2002]: "there is a widespread misconception that
electricity substitutes for biomass. Poor families use electricity
selectively - mostly for lighting and communication devices. They often
continue to cook with wood or dung, or with fossil-based fuels like LPG and
kerosene". This is certainly equally true for electricity from renewable
sources.
Charcoal, the provisioning of towns and cities
and climate aspects
But there are also
climate aspects of charcoaling. Low efficiency of conversion means increased
carbon emissions into the atmosphere[6], see Fig 5. Carbon is emitted in the
form of CO2, CO and CH4 (Methane). Of these, Methane is of particular
importance as it has a high Global Warming Potential (GWP), which is about
21 times that of CO2, calculated over a period of 100 years.
Making the best of urbanization
Photo 1. Solar cooker use in Sarh, Chad (Photo: Désirée Nguekadjita,
Sarh).
Energy invested and energy harvested by solar
cookers
Emission reductions through substitution of
charcoal by solar cookers
Photo 2: The papillon in a compound in Ouagadougou. Here it is used
to make mango marmalade for sale (Photo. Horst Meyer)
Solar cookers and jobs
Promotion of solar cookers
Photo 3: Solar Cooking demonstration on a market in Burkina Faso
(Photo P. Krämer)
Sources of information used:
