Industry energy

There is a continuously increasing demand for energy. The pressure to produce more energy is so high that the Volta River Authority (the energy-producing institution) lets

ro 4000

1961-1990 2010-2039 2070-2099

3000

2000

1961-1990 2010-2039 2070-2099

Fig. 9.4. Baseline yield projections for rice (left) and maize (right) under Hadley A2.

Table 9.3. Baseline crop production in tonnes.

1961-1990 2010-2039 2070-2099

Rice 71,478 85,866 103,136

Maize 833,373 956,536 440,510

1980 1988 1990 1992 1994 1996 1998

Fig. 9.5. Electric power use in Ghana. (Source: GLOWA, 2001.)

too much water through the dam with the hope that next year's rains will replenish the reservoir. When the rains are not so good for a single year, such as happened in 1997/98, there is no buffer and hydropower production comes to a halt. At present, hydropower generation is not very sustainable. The withdrawal rates are higher than the average inflow, leading to periodic shortages. The average annual generation is about 20,300 GJ and a graph of major users is presented in Fig. 9.5.

The Akosombo reservoir experienced two drought spells during the years 1983/84 and 1997/98, resulting in levels reducing below the minimum operating level (Fig. 9.6). As indicators for energy production we used the average energy production

Fig. 9.6. Water level of Lake Volta. (Source: GLOWA, 2001.)

Table 9.4. Projected average energy production at Akosombo using the Hadley model for scenarios A2 and B2 and the historical range.

Scenario

Hydropower (GJ)

HA2 10-39 HA2 70-99 HB2 10-39 HB2 70-99 Historical 1961-1990

21,595 18,742 22,177 21,809 18,116

and the frequency of years in which Lake Volta has water levels below the minimum operational level. The latter result in lack of power, at least during parts of the year.

Future climate predictions show increased rainfall, which would benefit hydropower generation. However, in addition to the increased rainfall there is also increased variability, because the standard deviation also increases. WEAP simulations (Table 9.4) show that in general average energy production increases due to the increase in runoff. The only exception is the Hadley A2 long-term scenario (2070-2099), under which results are similar to historical conditions.

Figure 9.7 shows the impact of climate change for individual years. The figure shows that there is a definite decrease in years of failure. With the exception of Hadley A2 2070-2099, there are no years with power failures any more. Under Hadley A2 2070-2099, there are still 6 years with lake levels below the minimum level of operation for part of the year, comparable to the 7 found under the historical simulations.

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