How off-grid renewables could power Tanzania's growth

Courtesy ofOff Grid Electric
Elizabeth Mukwimba is a 62-year-old Tanzanian woman who now has solar lighting and electricity in her home at the flick of a switch, thanks to an off-grid project.

The East African country of Tanzania faces a serious electrification challenge. Only 2 percent (PDF) of rural households have access to electricity, and most of the rural population relies on expensive, hazardous and low-quality fuels such as kerosene for lighting and charcoal for cooking.

Access to electricity and other modern energy services is fundamental to human well-being and to a country’s social and economic development. In many countries, electrification through off-grid applications has become a cost-effective alternative to conventional grid expansion in remote areas — and this could become a model that propels Tanzania's next phase of economic growth. Already in the country, energy systems based on wind, small hydropower, biomass and solar resources are being used successfully to meet energy demand in isolated villages. By integrating these renewable-powered off-grid systems, rural communities are increasing their access to affordable energy supplies while contributing meaningfully to climate change mitigation.

In 2013, per capita electricity consumption in Tanzania was 89 kilowatt-hours (kWh), one of the lowest rates in the world and only one-quarter of the average electricity use rate in sub-Saharan Africa (itself a region with record-low electrification). Among the main challenges faced by Tanzania’s energy sector are rising demand for rural electrification and the unreliability of electric utilities.

Rising demand for rural electrification

The demand for electricity is expanding rapidly in Tanzania, driven by factors such as population growth, increasing household consumption and booming mining activities.

In 2012, the Ministry of Energy and Minerals estimated that per capita electricity consumption would increase fivefold between 2010 and 2035, to 472 kWh (PDF). Currently, Tanzania’s national electrification rate is 11.5 percent, with a wide discrepancy between urban areas (40 percent) and rural areas (only 2 percent [PDF]). To close the gap, the government has set aggressive electrification targets, aiming to achieve 75 percent electrification by 2035.

Figure 1. Historical and target electrification rates in Tanzania, 1980-2035. (Source: OIES, 2016)

The vastness of the country coupled with low population density in some regions likely will present barriers to electrification.

The existing transmission line system fails to cover most of western and southern Tanzania, and grid extension would be uneconomical for many difficult-to-reach areas. Still, growing demands for electricity and for electricity access require the government to devise cost-effective electrification plans that could reach the rural population in a short amount of time.

Figure 2. Existing transmission network in Tanzania, 2013. (Source: IED, 2014)

Unreliability of electric utilities

Tanzania depends heavily on large hydropower (36 percent) projects and on fossil fuels such as oil and natural gas (62 percent [PDF]) for its electricity generation. In recent years, Tanzania Electric Supply Company (TANESCO), the main electric utility company, has suffered from poor management of grid maintenance and financial resources. Changing meteorological patterns and recent droughts dramatically have reduced generation capabilities from large hydropower, and the prolonged water shortage continues to cripple hydropower production.

TANESCO’s financial situation has been exacerbated by petroleum price volatility in the international market and by the need to acquire costly emergency and peak demand generators, hampering the company’s potential to invest in grid extension.

What's more, the over-reliance on large hydropower and fossil fuels has raised concern among electricity industry stakeholders in Tanzania. It also has opened an opportunity for significant uptake of micro-scale electrification schemes, which involve the participation of smaller power producers and require much less capital investment.

Emerging solution: Off-grid renewables

The World Bank estimates that the cost of grid extension in developing countries ranges (PDF) from $6,340 per kilometer in densely populated regions to as much as $19,070 per kilometer in regions with dispersed populations. The high cost of grid extension in remote areas presents enormous opportunities for off-grid electrification. In most cases, a single renewable technology will be insufficient to reliably meet electricity demand over long periods. To overcome this barrier, off-grid integrated renewable energy systems have been proposed to meet the growing demand from remote areas with locally available renewable energy resources.

Tanzania is a perfect candidate for off-grid integrated renewable energy systems, given the high cost of grid extension to its vast and often sparsely populated rural areas and the risks associated with grid unreliability. Off-grid systems can create a portfolio of highly diversified clean power sources with a wide geographical spread. Fortunately, Tanzania is home to immense and high-quality renewable resources. Aside from large hydropower projects, most of these resources — including solar, wind, small hydropower and biomass — have yet to be harnessed.

Vast potential for a variety of renewables

Solar: Situated in the world’s "solar belt," Tanzania receives abundant sunlight year-round, ranging between 2,800 and 3,500 hours of solar radiation per year and an average radiation of 4–7 kWh per square meter per day. Solar resources are particularly rich in the central region of the country. To make solar photovoltaic (PV) systems a more affordable and more attractive option, the government has removed the value-added tax (VAT) and import tax (PDF) for the main solar components.

Wind: Large areas in Tanzania are known for average wind speeds of 15 to 23 feet per second (PDF). More than 10 percent of the country, an area the size of Malawi, has areas of high wind power potential, and Tanzania’s overall wind potential exceeds that of the entire U.S. state of California in both wind speed and coverage. To date, four companies (PDF) have expressed interest in investing in wind energy in the country, and many regions are being assessed for their wind potential.

Figure 3. Wind energy potential in Tanzania (Source: IED, 2014)

Small hydropower: The assessed potential of small hydropower in Tanzania is around 480 megawatts (MW). Currently, the installed small hydro projects that are connected to the grid amount to only 15 MW. According to analysis from the National Electrification Program Prospectus, 141 hydropower sites have been identified that could supply electricity to more than 300 areas with populations over 1 million. The estimated capacity at two-thirds of these hydro sites is less than 1 MW, and at the remaining sites it varies between 1 and 10 MW. These are perfect values for small-scale electrification.

Figure 4. Sites with small hydropower potential in Tanzania. (Source: IED, 2014)

Biomass: Biomass-based fuel accounts for 88 percent of the primary energy supply in Tanzania, and about 80 percent (PDF) of this biomass energy use — primarily wood and charcoal — occurs in rural areas to meet residential cooking (and some heating) needs. Each year, charcoal production results in the loss of an estimated 371,728 acres (PDF) of forest cover in the country. As the population increases, scientists predict that some 6.91 million acres of forest will have been lost by 2030, equivalent to 8.5 percent of Tanzania’s total forest cover. The overexploitation of forests is unsustainable and severely challenges the concept of resource renewability.

Nonetheless, Tanzania’s potential for using biomass energy sources remains high. Among the abundant raw materials available for electricity production are sugarcane bagasse, rice husk and forest residues. Further supplies can be accessed through sustainably harvested wood from well-planned fast-growing tree plantations. The estimated theoretical potential for co-generation (the simultaneous production of electricity and heat, both of which are used) in Tanzania is over 395 MW. The current installed capacity of individual biomass-fueled plants varies between 100 and 500 kW.

Figure 5. Sites with electricity production potential from small biomass-fueled plants in Tanzania. (Source: IED, 2014)

Validation of off-grid renewables

Integrated renewable energy systems are designed to be greater than their individual parts, using two or more locally available renewable energy-based systems to meet the energy demand of remote areas without connecting to the main grid. By using multiple sources of energy, these systems overcome the uncertainty associated with a single renewable energy source. The International Energy Agency estimates that achieving the goal of universal access to electricity worldwide will require pursuing off-grid and/or micro-grid solutions in 70 percent (PDF) of the rural areas that currently lack access to electricity. These solutions hold particular promise in Tanzania, home to varied and extensive renewable energy resources.

In late 2012, the Rural Electrification Investment Prospectus stimated that "half of the rural population in Tanzania might be better served by mini grids (20 percent) and off-grid options (30 percent)" than by grid connection. A comparison of energy costs on a levelized basis shows that generating off-grid electricity using renewable energy could be cheaper than the conventional diesel option.

The integration of multiple accessible renewable energy sources would enhance the system and provide clean and renewable electricity for rural residents. The optimal sizing and configuration of the integrated system would be site-specific in order to minimize the cost of energy generation.

To test the potential of integrated renewable energy systems to meet the electricity demand of Tanzania’s remote and rural populations, a system simulation was performed in several regions using the microgrid model software Homer Pro, developed by the U.S. National Renewable Energy Laboratory. As most of Tanzania’s hydropower resources are in the south and west, and the majority of biomass potential is in the north, the simulation did not consider these two sources, focusing instead on a system that included wind, solar and traditional diesel plants.

As depicted in Figure 6 by the green shaded region, the configuration of wind, solar PV and diesel plants is economically feasible when the fuel price is very high and the wind speed is also substantial (greater than 19.5 feet per second). The red shaded region, the vast majority of the graph, depicts scenarios in which solar PV plus traditional energy sources work better together.

One important conclusion that can be drawn from the simulation is that solar has been a consistently cost-effective source to incorporate into the system. Depending on the availability and quality of other renewable energy sources, an optimized configuration can be structured to integrate multiple renewable energy sources.


Figure 6. Optimal renewable energy system configuration for Tanzania. (Source: Worldwatch)

Looking forward

In the future, most of the world’s population will live in areas that we refer to today as developing countries. Already, more than one-third of developing countries comprise rural areas that have no access to modern energy services. These remote areas, however, can and should be considered as potential early mover locations to demonstrate the tremendous potential of diverse renewable energy resources to satisfy growing energy needs — as in the case of rural Tanzania.

This article first appeared at Worldwatch Institute.