Agriculture Reference
In-Depth Information
consumers such as mines and aluminium companies account for one third of
total consumption. One industrial entity, the aluminium smelter VALCO,
accounts for most of this amount when it is operating normally. With a
customer base of approximately 1.4 million, it has been estimated that 45-
47% of Ghanaians, including 15-17% of the rural population, have access to
grid electricity, with a per capita electricity consumption of 358 kWh/a
(Resource Center for Energy Economics and Regulation, 2005)
The Akosombo dam is the backbone of Ghana's industrialization and
economic activities. It also supplies electricity to neighboring countries such
as Togo and Benin. Other benefits include: lake transportation, increased
fishing, new farming activities along the shoreline and tourism (Gyau-
Boakye, 2001).
The cost of electricity production from hydropower in Ghana is 0.02-0.025
US$/kWh and it is sold at a Bulk Electricity Price of below 0.04 US$/kWh.
The introduction of thermal plants for electricity production has increased
the average production cost to 0.06 US$/kWh and the Bulk Electricity Price
to 0.048 US$/kWh. Currently the End User Tariff is 0.082 US$/kWh
(Resource Center for Energy Economics and Regulation, 2005). So one cubic
metre of water used for hydropower generates 0.186 kWh which creates 0.015
US$/m 3 of revenue. Note that this is one order of magnitude smaller than
the lower bound profit generated from water used for tomato production.
8.6.3 Managing trade-offs between irrigated
agriculture upstream and hydropower
production downstream at Akosombo
The decrease in inflow into Lake Volta as a result of increased water
consumption for irrigated agriculture will negatively impact on hydropower
production. Reduced inflows may lead to reduced water levels which will
reduce the energy head available for electricity generation. To estimate the
impacts requires a representative data series of historical inflows into Lake
Volta, water levels, and electricity production, as well as some climate data,
characteristics of the lake and characteristics of the Akosombo plant.
A spreadsheet-based water balance model (Waflex, see Savenije, 1995) was
developed that could reproduce the water levels, electricity generated and
dam releases over the period 1985-1998. Since information on the dam
operating policies was lacking, the model was based on historical hydro-
power generation data and other hydrological data obtained from the VRA
and other institutions. Data obtained from the Volta River Authority (VRA)
and the Hydrological Services Department in Ghana was used to create
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