Using biogas technology to solve the disposal issues surrounding latrine waste
Practical Action
sustainable model, therefore by making each stage self managed all emptying contractors,
small or large will be able to participate as long as they conform to the program set out by the
overseeing organisation.
The economic argument
Initial investment
The initial issue (Bates 2007) is the high set-up costs of a biogas system. There are labour
and material costs associated with the digesters but also the construction of the gas delivery
method. Parkinson et al (2003) indentifies that although decentralised systems do reduce the
cost of investment in comparison to large complex centralised treatment infrastructure, the
majority of government agencies lack the funds to invest, so it is usual to look to the private
sector (Bates, 2007), higher levels of government (Parkinson & Tayler, 2003), or overseas
agencies (Myles, 2001) to help fund the project.
The issue with private backers is that very often they want a worthwhile return for their
investment, which is notoriously hard in sanitation, placing added pressure on the programme.
Community based organisations are often unreliable because it is hard to find a common
ground for all people involved that they all feel strongly for due to the perceived unimportance
of sanitation. A solution is to collaborate with a local water company, so the programme is
funded by the government, but run in conjunction with the community. This way there will be
less pressure to perform but there will be the management and technical backing to help the
programme succeed.
Willingness to pay
For gas usage: It is easy to see that to create willingness requires incentive. In this case the
incentive comes from the use of the gas; therefore it is imperative a use is picked that is
suitable to the community in question. There are a number of different uses for the facility
each with the positives and negatives. One idea is a communal kitchen type facility where
people could come and do cooking when and if they needed it, if accepted socially. One
possible issue with this is that some cultures may be averse to cooking communally/side-by-
side therefore knowledge of local practice will be required before choosing a kitchen. Another
issue would be the tariff structure and how the usage would be charged. One idea would be
per unit time because gas flow measurement from biogas is notoriously difficult. However,
charging per unit time can have an effect on the user because they will want to be in and out
as quick as possible which may lead to chaotic conditions and poor public opinion. Another
idea would be to package up the benefits so the user pays for the emptying and the use of the
communal facility is an extra. This creates the perfect situation for waste because the user will
not connect a direct cost with the gas, dropping the efficiency of the system. Another issue
that must be considered when assessing willingness to pay is habit, and the fact that many
communities will always cook certain foods using solid fuels. This means biogas will never
fully replace solid fuels for cooking because traditions are hard to remove. Another solution is
the market context, where the gas is used by a local business that pays a monthly fee for a
connection. This is based on the community needing the facility.
For emptying: Increasing the emptying frequency has been addressed but people’s willingness
to pay for this will further be improved by the natural risk spreading that will occur. If an
emptier does not turn up the implications to the home owner will be much smaller, compared
to a situation where the latrine is only emptied when it’s full. Research has looked at the issue
surrounding time horizons regarding sanitation and the fact people do not save up, they just
pay when it is time, so short time horizons are beneficial.
To work out a feasible emptying frequency a standard laboratory scale biogas experiment can
be used on a sample from the area so a decay curve of biogas production can be plotted. The
required production rate to meet demand will link to the samples age so the implementer will
know the emptying frequency required. Refer to Wilkie et al (2003) for a more detailed
method.
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