Factors Favouring Power and Energy Production – Power and Energy Production in the World (Senior 6 Geography) | Ganzaa

Power and Energy Production in the World

Lessons

Senior 6 · Geography

Power and Energy Production in the World

4 lessons

Lesson 3 of 4

Factors Favouring Power and Energy Production

25 min

Why there, and why then?

Between 1955 and 1959 a concrete wall 128 m high was built across the Zambezi River at Kariba Gorge, on the border of today's Zambia and Zimbabwe. The lake behind it is one of the largest reservoirs in the world, about 280 km long. Why was this gorge chosen, why in the 1950s, and who paid? Answering those three questions is the method of this lesson: every power station is the result of physical, economic, political and social factors acting together (Figure 1).

Figure 1: The four groups of factors that decide where power is produced.

Definition

Factor of production (energy): any condition that makes it possible or worthwhile to produce energy in a place.

Market: the homes, industries and services that will buy the power. Electricity is costly to send far, so a market must be within reach of transmission lines.

Transmission line: a high-voltage line that carries electricity from power stations to the places where it is used; some energy is always lost on the way.

Base load: the minimum demand that must be met all day and night. Peak load: the highest demand, in Rwanda usually in the evening when lights and cooking come on together.

Energy security: having enough affordable energy from reliable sources, without depending too much on one supplier or one route.

Physical factors

Presence of the resource. Coal, oil, gas and uranium must be found in workable quantities; a power station often stands on or near the field (the Highveld coalfields of South Africa; Lake Kivu's methane).
Relief and drainage. Hydropower needs a large, reliable river and a steep fall: gorges, waterfalls and rapids (Kariba, Inga on the Congo, the Rusumo Falls on the Akagera).
Geology. Dams need hard, watertight rock for their foundations; geothermal fields need hot rock close to the surface in rifts and volcanic zones, as at Olkaria in Kenya.
Climate. Rainfall that is heavy and well spread through the year keeps rivers flowing; many sunny hours favour solar power; steady winds favour wind farms. Drought cuts hydropower, as at Kariba in 2015–16 and again in 2024, when the lake fell very low.
Space. Reservoirs, solar fields and coal mines need large areas of flat or low-value land.

Economic factors

Capital. Power stations, dams and lines cost hundreds of millions of US dollars before they produce anything. Kariba was paid for partly by a World Bank loan of US$80 million in 1956, then the Bank's largest.
Market. A project goes ahead only if enough customers will buy the power: Kariba was built to supply the copper mines of the Zambian Copperbelt and the towns and industries of the region.
Technology and skills. Deep drilling, nuclear engineering or offshore wind need expertise that many countries must buy in.
Transport. Coal and oil must be moved to power stations; electricity needs transmission lines. A landlocked country pays more for imported fuel, which pushed Rwanda to develop its own sources.
Cost of the fuel. Hydro, solar and wind need no fuel; diesel plants must buy it every day (see Worked example 1).

Political factors

Government policy. Plans, laws and subsidies decide which sources are built. Rwanda's power plans are drawn up by MININFRA and Rwanda Energy Group, which signs agreements with private producers such as the Lake Kivu methane plants.
Stability. Investors avoid conflict zones; this is one reason the great potential at Inga is still largely unused.
Regional cooperation. Shared rivers need agreements: the 80 MW Rusumo Falls plant on the Rwanda–Tanzania border was built jointly by Rwanda, Burundi and Tanzania, which share its output.

Social and environmental factors

People to resettle. About 57 000 Tonga people were moved from the Zambezi valley to make way for Lake Kariba.
Environmental rules on pollution, emissions and protected areas, and an environmental impact assessment, can stop or change a project.
Public acceptance. Local opposition delays dams, nuclear plants and even wind farms.

Worked example 1: why fuel cost decides the choice

Problem. Two illustrative 10 MW plants are each expected to last 25 years. A solar plant costs US$10 million to build, has a capacity factor of 0.18 and needs no fuel. A diesel plant costs US$4 million, has a capacity factor of 0.50 and spends US$200 on fuel for every MWh it generates. Ignoring interest and maintenance, compare their cost per MWh.

Solution. Find the energy produced each year, then share the building cost over the plant's lifetime output.

\text{Solar: } 10 \times 8\,760 \times 0.18 = 15\,768\ \text{MWh per year}

\frac{10\,000\,000}{15\,768 \times 25} \approx 25\ \text{US\$ per MWh}

\text{Diesel: } 10 \times 8\,760 \times 0.50 = 43\,800\ \text{MWh per year}

\frac{4\,000\,000}{43\,800 \times 25} + 200 \approx 3.7 + 200 \approx 204\ \text{US\$ per MWh}

The diesel plant is cheaper to build but about eight times dearer per MWh, because fuel must be bought for every unit. That is why diesel is kept for emergencies and peaks; REG reports that Rwanda's diesel plants supply only about 1% of its electricity. The solar plant, however, produces only by day, so it needs storage or other plants for the evening peak.

Worked example 2: choosing a site for a small hydropower plant

Problem. Three illustrative sites are studied on a river in Rwanda. Using $P = \rho g Q h \eta$ with $\eta = 0.85$ and the dry-season flow, rank them and recommend one.

Site	Head (m)	Dry-season flow (m³ s⁻¹)	Distance to grid (km)	People to resettle
A	60	2.0	5	0
B	25	6.0	30	400
C	80	1.5	45	50

Solution. $\rho g \eta = 1000 \times 9.81 \times 0.85 = 8\,338.5$ , so in kilowatts $P \approx 8.34\,Q\,h$ .

P_A \approx 8.34 \times 2.0 \times 60 \approx 1\,000\ \text{kW} \qquad P_B \approx 8.34 \times 6.0 \times 25 \approx 1\,250\ \text{kW} \qquad P_C \approx 8.34 \times 1.5 \times 80 \approx 1\,000\ \text{kW}

Site B gives the most power, but it needs 30 km of new line and the resettlement of 400 people. Site C gives the same power as A but is 45 km from the grid. Recommendation: site A, because it gives 1.0 MW in the dry season close to the grid and moves nobody. The physical factor (power) is not decisive on its own; economic and social factors change the ranking.

Case study: geothermal power at Olkaria, Kenya

Kenya's geothermal power shows the factors working together. Physically, the Olkaria field lies inside the Rift Valley near Lake Naivasha, where magma heats rocks close to the surface and steam can be tapped from wells about 2–3 km deep. Economically, the steam is free once wells are drilled, so the power is cheap and steady, ideal for base load; Kenya's growing towns and industries are the market. Politically, the government created a public generating company, KenGen, and a Geothermal Development Company to carry the risk of drilling, which private firms avoid. The result: geothermal power supplied 43.2% of Kenya's electricity in 2024 (IEA). The limits are social and environmental: the field lies in and around Hell's Gate National Park, and some Maasai families have been resettled to make way for new plants.

Warning

Common mistake. Answering "factors favouring power production" with physical factors alone. Rwanda has many rivers and steep slopes, yet most of its hydropower potential was unused for decades because capital, a large market and grid lines were missing. Always give examples from at least three groups, and show how they interact.

Tip

Memory hook: "PEPS". Physical, Economic, Political, Social. For each named power station in your notes, write one fact under each letter. That turns a list into a case study.

Al Jazeera English: "Kenya's geothermal energy to lift millions out of poverty", reported by Catherine Soi from the Olkaria plant in the Rift Valley. As you watch, note one physical, one economic and one social factor behind the project.

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Practice

Name four physical factors that favour the building of a hydroelectric power station.
Explain why a large market is needed before a power station is built.
Explain how political factors helped the Rusumo Falls project.
Using Worked example 1, how much would the diesel plant's cost per MWh be if fuel rose to US$250 per MWh?
A small hydro site has a head of 40 m and a dry-season flow of 3 m³ s⁻¹ (η = 0.85). Calculate its dry-season power in kW.
Explain why drought is a threat to countries that depend on hydropower, with an example.
Assess the relative importance of physical and economic factors in the development of power in Rwanda.

Show answersHide answers

Any four: a large, reliable river; a steep gradient, waterfall or gorge; hard, watertight rock; a site for a reservoir; heavy, well-distributed rainfall.
Building is very costly, and the cost is repaid only by selling electricity; without enough customers within reach of lines, the plant would lose money.
Rwanda, Burundi and Tanzania agreed to build and share the plant on their shared river, so no one country bore all the cost, and the regional agreement attracted funding.
3.7 + 250 ≈ US$254 per MWh.
P ≈ 8.34 × 3 × 40 ≈ 1 000 kW (8.3385 × 120 = 1 000.6 kW).
Output depends on river flow and reservoir level, so a drought cuts generation and causes power cuts: for example, Lake Kariba fell very low in 2015–16 and 2024, forcing Zambia and Zimbabwe to ration power.
Physical factors give Rwanda rivers, steep slopes, Lake Kivu methane, peat and sunshine. But economic factors decide which are used: capital, a market large enough to repay investment, and the cost of lines to scattered hill villages. Political factors (plans by MININFRA and REG, agreements with private producers and neighbours) turned the resources into power. A good answer judges that physical factors make power possible, while economic and political factors decide whether and when it is produced.

Summary

Power production depends on physical (resource, relief, geology, climate), economic (capital, market, technology, transport, fuel cost), political (policy, stability, cooperation) and social and environmental factors.
Kariba shows all four: a hard-rock gorge on a great river, World Bank capital, the Copperbelt market, and the resettlement of about 57 000 Tonga people.
Fuel cost explains why countries prefer hydro, solar and geothermal for base supply and keep diesel for emergencies.

Sources and credits

Kariba Dam and Olkaria Geothermal Power Station: Wikipedia contributors, CC BY-SA 4.0, adapted by Ganzaa.
Kenya's electricity mix: Energy Statistics Data Browser, IEA, 2024 data, retrieved 2 October 2026. Data cited, not copied.
Rwandan facts: Rwanda Energy Group, Rwanda Least Cost Power Development Plan, 2024 Review (2025). Facts cited, not copied.

Photos: Kariba Dam Wall (JonGT, CC BY-SA 4.0) and Olkaria V Geothermal Power Station (Macabe5387, CC BY-SA 4.0), via Wikimedia Commons.

Video: "Kenya's geothermal energy to lift millions out of poverty", Al Jazeera English, embedded from YouTube.

Figure 1, the worked examples and exercises: written by Ganzaa.

This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.

1Why there, and why then?

2Physical factors

3Economic factors

4Political factors

5Social and environmental factors

6Case study: geothermal power at Olkaria, Kenya