12 minute read
LIGHTING UP A CONTINENT
Autonomous electricity grids are powering a socioeconomic revolution in rural Africa
Aaron Leopold, executive director, African Minigrid Developers Association
Elizabeth Mukwimba, a 62-year-old Tanzanian woman, poses beside the controller for her newly installed solar system. The money she has saved by not having to buy kerosene to light her home at night has already enabled her to replace its tin roof
In a remote village in Nigeria, a young girl flicks a switch and her small bedroom is bathed in light. This small act, taken for granted by children in the West, represents a revolution in rural Africa. Instead of having to study in the weak light produced by a smoky kerosene lamp, the young student can work in bright light long into the night. Numerous studies have seen an increase in both the amount time students spend studying and their test scores when their homes are electrified.
Ensuring universal access to affordable, reliable, sustainable and modern energy is one of the UN’s Sustainable Development Goals. At present, however, more than 640 million Africans, some two-thirds of the continent’s population, lack access to electricity.
Africa has the world’s fastestgrowing population, which is, in turn, creating a rapidly increasing demand for energy; the African Energy Chamber projects that the continent’s power demands could double by 2050. And governments are struggling to keep up.
Energy poverty can act as a brake on economic growth. In otherwise self-sufficient local communities, it can handicap development, and a lack of available energy is a factor in rural to urban migration.
Access to electricity allows people to pump and purify water, gain access to telecommunications networks and power appliances and machinery to reduce manual labour. Communities can light streets and provide power to schools and healthcare facilities. Farmers can use irrigation pumps to increase crop yields and preserve produce with cold storage. And, yes, children can study for longer at night.
In the past, African governments have mostly relied on expanding the existing centralised power grid in order to improve access, but this has led to a large urban–rural divide, with about 60 per cent of the urban population having access to electricity compared to only 15 per cent of the rural population. This is largely due to the fact that the continent is home to hundreds of thousands of remote communities that are located far from the central grid. The cost of electrifying these communities is too great in terms of both time and money. And across most of Africa, the central grid is already overburdened, so adding more customers isn’t a good solution. Delivering power to remote areas is also inefficient because some of the electricity – as much as 15 per cent – is lost in transit.
Increasingly, governments and aid agencies are turning to what are known as minigrids or microgrids (the two terms are generally poorly defined [see Macro, mini, micro or nano?]; for the purposes of this article, microgrid will be used as an umbrella term). Essentially decentralised electrical grids, microgrids are self-sufficient energy systems that serve a discrete geographical area. They are typically powered by one or more types of distributed energy source, such as solar panels, wind turbines, fuel cells and biomass and diesel generators. Although they may be connected to the central grid, crucially, they can function completely independently, a capability known as islanding.
Microgrids offer numerous benefits. Their autonomy insulates them from the negative aspects of larger power grids, such as rolling blackouts. Most microgrids use renewable energy sources, which helps governments meet their Paris Agreement and other climate-related responsibilities. They are significantly more cost-effective THE TERMS USED to describe power grids are poorly defined and often used interchangeably.
■ MACRO-GRIDS: large regional or central grids that connect large numbers of people over wide areas to energy supplies.
■ MINI-GRIDS: like macrogrids on a much smaller scale, operating over a small, lowvoltage localised distribution network and powered by distributed energy resources. Some organisations define minigrids in terms of their generation capacity, with stated ranges usually falling between 50 kW and 10 MW. They can either be fully autonomous or connected to a macro-grid, although some definitions specify that only the former qualify. They should be able to serve larger commercial and small industrial loads.
■ MICROGRIDS: similar to minigrids but even smaller, with a generation capacity of between one and 50 kW. They, too, can be either fully autonomous or connected to a macro-grid, although again, some definitions specify that only the former qualify. The types of loads they serve are usually residential only, or very small commercial.
■ NANO-GRIDS: grids that serve a single customer or building using a single generation unit and don’t use transmission or distribution lines. ■
A satellite image of Africa at night illustrates the continent’s lack of lights
More than 640 million Africans, some twothirds of the continent’s population, lack access to electricity MACRO, MINI, MICRO OR NANO?
than simply expanding the existing electricity grid; upfront costs to connect to the utility grid can run to several thousand US dollars, whereas the cost of an average microgrid connection is less than US$1,000 and continuing to fall (between 2014 and 2018, the cost more than halved). They can also be set up quickly; it can take as little as two months to install a typical microgrid. And because microgrids are modular, they are relatively easy to upgrade and to integrate with other microgrids and conventional power grids.
According to the World Bank, more than half of the world’s unelectrified population would be most costeffectively served via microgrids. However, the scale of the situation is daunting; World Bank estimates suggest that universal electrification in Africa would require more than 140,000 community-scale microgrids.
Many African governments have seized on microgrids as the solution to their electrification woes. The Kenyan government recently launched the US$150million Kenya
A large array of solar panels can power an entire village
Off-Grid Solar Access Project, which aims to provide 5.2 million new electrical connections to rural populations through support for hundreds of new microgrid sites and millions of new solar home systems. The Nigerian government hopes that by 2030 it will be generating 5.3 GW from at least 10,000 microgrids. And Cameroon recently launched a public-private partnership aimed
Joyce, a 12-year-old Tanzanian schoolgirl, is now able to study at home at night, thanks to a solar lighting scheme backed by UK aid
at installing 750 microgrids to bring electricity to some of the 11,000-plus villages in the West African nation that currently lack power.
Aid agencies are similarly enthusiastic. The US government’s Beyond the Grid programme has committed to investing more than US$1billion to provide renewable microgrid solutions in sub-Saharan Africa. The initiative hopes to bring
30,000 MW of electricity to more than 60 million African households in remote and rural regions by 2030.
Although many of the projects currently underway are being funded through a mixture of public and foreign aid funds, private businesses are also becoming increasingly active. For these organisations, achieving profitability requires tailoring the microgrid to the community’s needs: if the system is too large, it will be underutilised, leading to high per-unit costs; if it’s too small, it will forego revenue and scale effects, again leading to higher per-unit costs.
Among those taking part in the microgrid roll-out is African renewable energy provider PowerGen, which has installed utilities for more than 50,000 people in Somalia, Kenya, Tanzania, Mozambique, Zambia, Uganda, Rwanda, Benin and Niger. According to PowerGen CEO Sam Slaughter, the organisation’s microgrids typically serve 100–500 connections and have ground, AI and ML are being used with advanced geospatial processing techniques to extract information from satellite imagery. For example, medium-resolution imagery can be used to identify settlements of people without energy access and features relevant for a specific project, such as the distance to the nearest city, distance to water and population size. High-resolution imagery can then be used to gain information on parameters such as demography, economy and purchasing power, including the level and patterns of commercialisation, which will affect demand. Together, this information helps companies to determine the best locations for projects.
Residents lift a solar panel in Gbandiwlo village, Sierra Leone
a geographic radius of less than one kilometre. The company hopes to expand energy access to a million more Africans by 2025.
One of the keys to the success of for-profit microgrids is the PAYGO business model, whereby people use mobile money to pay their energy bills. Advancements in smart meters, management systems and battery technology, as well as significant cost reductions in solar panels and storage batteries are also important factors.
Companies installing microgrids across Africa are increasingly using a mixture of artificial intelligence (AI) and machine learning (ML) to make their operations more efficient. Before work on a project begins on the
MINING AND MICROGRIDS
MICROGRIDS ARE ALSO
increasingly being embraced by the mining industry. Mining is an energy-intensive industry (energy accounts for up to 30 per cent of operating costs for a typical mining operation), but mines are often located in remote, off-grid locations, so mine operators have limited options for decarbonising their operations. They typically have to rely on unreliable oil-fuelled generators, but with the falling cost of solar PV and improvements to battery design, many miners are turning to solar microgrids. A one-megawatt solar plant will typically produce 2,000 MWh annually – the equivalent of using about half a million litres of diesel.
Even when there is an option to connect to the main grid, there are often problems with the reliability of supply, which can be smoothed out by connecting a microgrid to the main grid. The battery compensates for any shortfalls in generation.
In South Africa’s North West province, the Vametco vanadium mine recently announced plans to use vanadium redox flow batteries (VRFB) to store energy from a 3.5 MW solar PV plant, which will supply almost ten per cent of the mine’s electrical needs. VRFB technology, which uses large electrolyte storage tanks, can easily be scaled up to provide almost unlimited energy capacity. The microgrid is projected to reduce carbon emissions by more than 13,000 tonnes over its 20-year lifespan. ■
Solar panels require little maintenance
In Nigeria, NGO Renewable Africa 365 is using AI to develop a gridcoverage analysis and ML-driven heatmaps to identify the sites that are most suitable for solar panel installation. These have then been coupled with an interactive map of regions with a high demand for electricity.
Because they tend to rely on renewable energy sources, whose output is often highly variable, and they serve communities in which demand is also highly variable, energy management within a microgrid can be extremely complicated. The microgrid may need to regularly transition between grid-connected and island modes of operation. It needs to know when and where to store energy, and perhaps even which buildings get power at which times. These decisions are made by the microgrid’s controller, which regulates the different generators, batteries and inverters, and the flow of energy among them. AI is increasingly being used to make this decision-making more efficient. Algorithms may use historical data, weather data and associated load predictions to manage supply.
AI-enabled controllers can also track real-time changes in the wholesale power prices on the central grid, which constantly fluctuate with supply and demand. When prices are low, the controller may choose to buy power from the central grid and use the microgrid’s solar panels to charge its batteries. Later, when grid power is expensive, the microgrid can discharge its batteries rather than using grid power.
The use of smart inverters, which balance out the demands on the system, matching energy consumption and generation, and siphoning off the excess into battery storage, has been particularly important. Like traditional inverters, smart inverters convert the direct current output of solar panels into alternating current for use by consumers. However, they go beyond this basic function to provide gridsupport functions, such as voltage regulation and frequency support.
Smart inverters also allow flexibility, enabling the addition of more energygeneration capacity as demand grows, which means that grids can be built with capacity to meet only the initial demand. And they can extend the system’s reach beyond the typical 600-metre range of a low-voltage distribution network by boosting the voltage at the network’s periphery. And finally, if the main grid is extended to reach these rural communities, smart inverters allow the microgrids to be connected to the main grid. ‘For the last five years, I’ve believed that mini-grids can connect unelectrified citizens and businesses in Africa more quickly, more cheaply and more sustainably than main-grid connections can,’ says Jon Lane, associate director of the Carbon Trust. ‘Smart inverter technology takes this a stage further by connecting both options to ensure that we leave no-one behind and provide the best possible service to all.’
At present, the most significant barrier to the widespread roll-out of microgrids are regulatory compliance processes, which can take, on average, more than a year per site. For-profit microgrids also face the challenge of low consumption; the average consumption per customer is only 6.1 kWh per month across the continent. This makes it difficult for companies to ensure that operational costs – let alone return on investment – are covered for residential consumers.
However, momentum appears to be on the microgrids’ side and as costs continue to come down and partnerships between microgrid developers, governments and aid agencies continue to multiply, it certainly seems as though rural Africa’s future is bright. ■
CASE STUDY
ANNOBON ISLAND MICROGRID
LOCATED OFF THE coast of Equatorial Guinea, Annobon Island is home to about 5,000 people. In the past, the island only had reliable electricity for up to five hours per day and residents spent an average of 15–20 per cent of their income on supplemental power. The government of Equatorial Guinea contracted MAECI Solar and Princeton Power Systems to install a 5MW solar microgrid system on the island, featuring 20,000 solar panels in three separate arrays, system integration, an energy-management system consisting of twenty 250 kW battery integrated inverters installed across the island to manage power flow between the different sources and loads, remote control/update capabilities and three large-scale advanced battery banks. When it was installed in 2015, it was the largest self-sufficient solar project in Africa. Today, the microgrid supplies enough green electricity to meet all of the island’s current energy demands. ■
