|
Energy for Domestic use and Blind Centre
1. Wind generator (size to be determined but at least
1 kilowatt)
For all electricity needs wind would be suitable in this area.
Wind blows regularly from approximately 11.00 to sunset all the
year round. Calculations of likely needs should affect the decision
on size of generator. Battery storage would be needed if there
is no connection to the grid. The evening wind (reverse direction)
is probably not strong enough to generate power.
e.g Bergey BWC 1500 watts. Cost: £2517 ($3775 imported
from US to UK, therefore, better deal might be possible in US).
Other costs for battery storage and control devices. (mentioned
for comparison only).
This assumes that no wind energy will be sold to other users.
If energy is to be sold a larger installation would be appropriate.
Battery storage
The capacity (and cost) of batteries for storage depends
on the amount of electricity used when the wind is not blowing
(night and early morning) or the sun is not shining. Thus, if
it can be arranged to use such devices as power tools and washing
machine only during time of maximum wind speed, storage need
be only enough for evening lighting, TVs, computers and so on.
For sites in Europe, storage must take account of days without
wind and may have to store the power used on three or more days.
In the Winam(22)# area this is not necessary as the wind blows
every day.
2. Wind pump. A standard wind pump can be used for
pumping water from the lake. The writer is assuming that no part
of the site is likely to be above the reach of a wind pump (10
metres). The water system, including a small purification plant,
can be situated below a header tank supplied by the wind pump.
There may be some scope for irrigation during the dry season,
in which case a larger pump would be appropriate than would be
needed for domestic needs alone.
3. Solar water heating. This is not as important as
in Europe but would be useful for clothes washing and showers.
A cheap system would be satisfactory. (A Gravity device without
secondary cycle is adequate. Even a pipe painted black without
glass or plastic cover might be sufficient.)
4. Solar electricity (smaller wattage as backup)
The wind doesn't blow for part of the day. There are uses for
early morning power. Solar electricity probably remains more
expensive than wind power but should be installed as an example
for areas away from the main wind system and in anticipation
of later developments (cheaper photovoltaics or possible carbon
taxes).
5. Biogas: A biogas project depends on the availability
of suitable waste materials. Biogas is the ideal energy for cooking,
if a supply of material can be found. Vegetable waste from the
lake might be a source: reeds from sudd beds. Some animal
waste is also necessary. If there is to be a chicken farm, a
biogas plant is a natural adjunct. The chicken manure can produce
gas, then be used as compost on a vegetable plot. If it is added
to vegetable wastes such as reeds from the lake and crop wastes
while digesting, there would be many advantages (lack of hydrogen
sulphide; increased quantities of gas; soil conditioner). A biogas
plant ought to be big enough to produce 10 cu metres/day. The
temperature conditions on Rusinga are ideal for biogas - optimum
temperature 25 - 30oc - so that the digesters are much cheaper
than in Europe (no insulation or heating required). It would
be necessary for the proposed Rusinga Agricultural Project and
the Blind Training centre to be located on adjacent sites.
Training
Local people should be trained in maintenance of these technologies.
In fact, there might be an occasion for running courses on energy
at the practical level to encourage others to adopt these technologies.
(Handbooks, audio tapes etc. in English and local languages).
Using this power
6. Lighting: low voltage lights from batteries charged
by wind and sun. Low voltage doesn't have to mean dim, but 12
and 24 volt DC equipment is convenient and available off the
shelf. 24 volt is better, as cables can be thinner or longer.
(1989. Now, 2002 I would recommend 240 volt apparatus, using
an inverter, which is now cheaper and more efficient then then).
7. Cooking: In Rusinga conditions cooking might be
best done with biogas, but this depends on the availability of
suitable material. If there is a large supply of biogas (10 +
cu metres/day), all cooking can be done with it (provided the
source is near enough to pipe the gas to the users).
An Electric Aga (as in NCAT Machynlleth). In a very windy
area where wind varies in intensity the surplus electricity can
be run into the Aga which is thus kept always warm. The capital
cost of an Aga in Rusinga would probably not justify this method,
so that electricity should probably not be used for cooking.
In any case wind on Rusinga does not vary greatly.
Hydrogen
Hydrogen is potentially another system for cooking proposed for
European projects, but the technology is still too expensive
without a large grant from someone. Only when there are mass
produced hydrogen generators will it be possible to use it for
many of the purposes where gas and oil products are used today.
When it becomes available cooking could be done with stored hydrogen.
In the Rusinga area it is possible to imagine for the future
that large scale wind projects might sell energy in the form
of hydrogen for such purposes as road transport. (This depends
on oil being taxed highly at the source, or unavailable).
Charcoal
As far as possible firewood and charcoal should be avoided because
of deforestation, unless a fuelwood plantation can be planted.
However, population density rules this out in most parts of Kenya.
Increased population density is making firewood an unacceptable
fuel.
8. Other Household machines
- Fridges designed to work off kerosene can be adapted for any
heat source. Thermoelectric types (Peltier effect) are ideal
to run off low voltage DC power. Neither type contains moving
parts or CFCs. Kerosene fridges can be run off biogas. If there
is a large enough supply, biogas would be the best source for
refrigeration. Kerosene types may be available locally, new and
second hand. Thermoelectric would have to be imported.
- Vacuum cleaner, probably through an inverter, though low voltage
types may be available.
- Washing machine This may be the largest power need and therefore
the determining factor in the size of system. It would need inverter
power and should probably be used only while the wind is blowing.
- tv & Computers can all be run off 12 or 24 volt supply
either directly or with Inverter to 240v. The same is true of
Power Tools.
Inverter
An inverter to run 240 volt AC apparatus wastes some of the energy
in the process, so should be used only for those things which
cannot be provided any other way. The size and frequency of use
of the inverter might determine the number of batteries you need
for storage. (now, 2002, they are much more efficient)
In a large project it might be worth using 240 volts AC as
standard and running all power through an inverter. An advantage
is that standard wiring and sockets can be used in the buildings.
However, the sockets are unlikely to be able to deliver all the
power needs of a grid connected system. In Rusinga there is no
danger of large heaters being connected, though electric kettles
and toasters would also have to be excluded.
Batteries are an expensive part of the whole system, and must
be protected# from going flat.
Transport
At present the capital required for running transport with income
energy is probably beyond the scope of this project. Donkeys
and sailing boats run on income sources. In the past sailing
boats were an important transport means in this area. Probably
only a high rise in oil prices would bring them back. Alternatives
to motor fuel might be: alcohol, hydrogen, biogas. They would
need to be the subject of a different project.
Past Wind Work
There is a history of attempts to use wind in the Mbita area.
They are described in the 1982 report of van Lierop & Veldhuizen.
Despite a good deal of work throughout the 70s, by 1982 very
little seems to have been achieved - in the sense that few wind
machines had been installed. This makes one wonder whether this
proposed project is likely to succeed any better. One of the
purposes of an inspection trip is to discover whether any progress
has been made since 1982.
Failure, thinking about people
What are the actual reasons for the failure of wind projects
so far? Is it that local people have seen no advantage in adopting
the technology, or have had no opportunity to do so, that is,
no access to capital? Or is it that even if one increases production
with wind technology (with irrigation) there is no market for
the increased production and so no increased sales? Or is it
that people are still not interested in increasing sales? Van
Lierop & Veldhuizen refer(24)#, obscurely, to "socio-economic"
problems in the area south of Homa Bay as being prohibitive.
The Nyanza area in general is classified as "of high potential";
however, the actual lakeside littoral is labelled as only of
"moderate" potential for irrigation. This may reflect
the fact that there is a rainy season so that non-irrigated agriculture
is likely to be as important as irrigated (and perhaps people
value the dry season as a time for other activities, which would
be disturbed if they have to work through it).
There is little mention of electricity in the report, perhaps
because in actual competition with currently cheap diesel, and
with grid power, wind was not seen as being competitive(25)#.
But it may be that it is just that people have few needs for
electricity, even if they make it themselves. The elite will
use diesel engines anyway, if they are off the grid, as they
have no other desire than convenience. An aim of developing wind
electricity for geotherapeutic reasons may over-rule the current
cost disadvantage(26)#, but it will not spread spontaneously
until carbon fuels actually rise in price as a result of scarcity,
or of world ecological policy, or if a California energy regime
could be installed. There will always be a tendency for convenience
to outweigh ecological desirability.
The failures tend to suggest that people's needs and desires
are more important than technology. It is fairly easy to look
at technology and see what is possible. It is much more difficult
to find out what suits people.
|