Microgrids: Could Africa Become a Pioneer?
Africa has become a laboratory for new kinds of electricity microgrids, nanogrids and other systems that rely on low-cost, renewable energy sources.
More than 620 million Africans are unable to turn on a lightbulb, charge a cellphone or keep a fridge running. As a result, there's a technological footrace underway to provide electricity to them without burning more fossil fuels.
Africa has become a laboratory of sorts for new kinds of electricity microgrids, nanogrids and other systems that rely on low-cost, renewable energy sources like wind, solar and small-scale hydropower.
"The technologies are getting better and cheaper," said Kevin Watkins, director of the Overseas Development Institute in London and author of a new report on African energy by the Africa Progress Panel, a group headed by Kofi Annan.
Watkins says that even with the proposed expansion of existing electric power grids in many African nations, there will still be 400 million to 500 million people without power by 2030. In order to close that gap, Watkins and others are pushing for small scale systems that cover several dozen to several thousand people, or even just one family.
"You only have to generate 100 watts to 300 watts, which is sufficient to power a few lightbulbs, a phone charger, a radio or maybe small fridge," said Watkins. "The key issue identified that this is a real market. This isn't an aid story."
Watkins says microgrids, which are small electric systems independent of a national grid, and nanogrids, which are single-household power systems, are taking advantage of cheaper and more efficient lithium batteries, LED bulbs and solar panels.
"Poor people are already engaged in the energy market," Watkins said. "But they are engaged in least efficient models: they are buying charcoal, flashlights, and candles or spending long hours collecting wood."
The report noted that Africans spent $10 billion each year on energy, often paying 15 to 20 times more per kilowatt hour than families in the United States. Four of five African homes burn wood or other forms of biomass, burning that generates smoke and other fumes that kill 600,000 people each year, the report noted.
In recent years, private groups and government agencies are teaming up to get some of these microgrids off the ground. The U.S. Agency for International Development currently is managing 24 off-grid power projects in six African countries worth $2.4 million.
The USAID program challenges African companies to come up with locally run programs. The current batch of USAID projects includes five solar systems, three biogas generation projects, and a small hydro-electricity power plant, providing over 10,000 people with access to electricity.
Through a USAID challenge grant announced in July 2015, Kenya's Ambalian Company is installing a wind turbine in one of northern Kenya's rural communities to replace diesel-powered generators used currently to pump water.
Rafode, a local Kenyan microfinance organization, will provide credit to fisherman in the Lake Victoria region to purchase solar lamps, thereby boosting the catch from their traditional nighttime fishing. And in Nigeria, Ajima Farms will develop a major biogas plant to provide electricity to homes and businesses currently living off the grid, according to USAID.
The ODI's Watkins is spearheading a separate program along with several African partners to provide electricity for five million households in five nations within the next five years.
"I do think it's achievable," Watkins said.
The biggest obstacles are the initial set-up costs for household solar (which are as little as $70 to $90 per system), resistance by local officials who are tied to existing utilities that are both unreliable and corrupt.
"In much of Africa, the state energy utilities are centers of vested interested, corruption and patronage," Watkins said. "If you develop off grid you are bypassing these guys."
Another worry is building robust microgrid that won't have a software glitch or other technical problem a few years down the road, according to Ken Horne, associate director at Navigant Consulting and an expert in microgrid systems.
"If you try to deploy a small microgrid in Africa and it is hundreds of miles away from the nearest pole," Horne said, "the challenge is that you have to operate it very carefully because you don't have a backup."
Not all Western firms are looking to hook up villages or rural cities. Arnaud Henin, president of London-based Gommyr Energy Networks, just returned from Katanga province in the Democratic Republic of Congo.
While the area relies on inexpensive hydropower from nearby rivers, the region's copper mines suffer four or five blackouts per day and are using diesel as a backup. Henin is setting up new smart grid technologies to better manage the flow of energy, as well as solar systems that can make the mines more productive.
The next step is connecting rural communities who will pay for their power through cellphone banking. Given all these changes, Henin believes the future looks bright for Africa's power supply.
"All these emerging markets will avoid having centralized grids like we have in North America or Europe," Henin said. "Power will be generated locally, and the shift away from diesel and fossil fuels to renewables cuts the links to the oil market. It takes time, and there will definitely be bumps on the way."
Redesigning the traditional wind turbine -- large three-bladed rotors with controllable pitch -- is sort of like reinventing the wheel. Decades of trial, error and testing go into it. Bob Thresher, a research fellow at the National Renewable Energy Lab in Golden, Colorado, would know. He’s spent more than 40 years working in the wind energy field and helped start the National Wind Technology Center.
“I’ve spent my entire working life developing kinetic art that’s useful,” he said.
But conventional wind turbines remain expensive and require tons of material. The ongoing quest for cheaper, more efficient wind energy has produced wacky wind turbine ideas. Thresher offers his grounded take on some of the most promising ones.
Airborne wind turbines resembling kites, planes, balloons, flying figure eights and nearly everything in between are actively being developed. Joby Energy’s multi-wing system and KiteGen’s kite-like turbines have made headlines. In 2009, the Airborne Wind Energy Industry Association formed to promote the stakeholders in this nascent sector.
The idea of tapping winds higher in the atmosphere makes sense, Thresher said. But the challenges for flying or light air devices also increase exponentially. Airspace is tight. Plus, a bad day for a wind turbine on the ground is when the rotor smashes the tower. “If you’ve got a bad day in the air you might cut your cable and then where are you going to land? You’ve got some liability issues,” Thresher said. Going offshore or a place with a large expanse could help minimize the risks, he added.
Some engineers have looked to building structures, redesigning them to tap wind energy. Last year a company called Clean Wind Energy Tower Inc. got approval to develop two https://www.seeker.com/tech/downdraft-wind-tower-120606.htm Downdraft Towers in Arizona. The concept works like this: Water is pumped to the top of the 2,000-foot-tall cylindrical tower and sprayed into a mist. That cools the air, causing it to sink rapidly, at speeds up to 50 miles per hour. The falling air rushing through the bottom, where there are turbines that convert the motion into electricity.
Thresher compared the tower to an ocean thermal energy conversion or OTEC, where a device in the ocean picks up cold water from the bottom and warm water from the surface to run a heat engine on the temperature difference. The trouble is that to produce significant amounts of energy, the device has to be huge, he said. Then the structural cost is also high due to the large size. And, forget about planning offices or homes for wind energy buildings. In general, Thresher said, people tend to avoid living in windy places. “Look at Wyoming: great wind, no people.”
Vertical-axis wind turbines are among the less wacky on the list. Operational ones are already up and running. Their power curve is similar to conventional horizontal axis turbines. In these designs, the main rotor shaft is arranged vertically, often with the blades swirling around in a helix formation. The Swedish company Ehmberg Solutions AB took this a step further, creating a flywheel design called SeaTwirl intended to be anchored on the seafloor.
The big challenge here is making such a system cost-effective, Thresher said, but with enough development it could be a horse race with traditional turbines. “We proposed looking back at vertical axis turbines for offshore,” he added. “We have some energy around the idea that it might be doable.”
Funnel-like wind devices can be traced back to the 1970s, when the first diffuser was proposed. Thresher said the most high-tech one today is an aerodynamic jet-engine style structure from Massachusetts-based FloDesign Wind Turbine Corporation. Their shrouded turbine works by creating a rapid-mixing vortex when wind hits it, and has fins that allow it to turn into the wind for maximum energy. The tricky part is that a device with a shroud needs to be able to survive hurricane-force winds.
“You can’t feather it,” Thresher said. “You can’t minimize the drag -- you’ve got this big shroud out there.” Another challenge, as usual, is cost. The larger the foundation and structure, the higher the cost. To mitigate the added weight and cost, some designers are considering structural fabric or polymer skin for the parts. Thresher added that he thinks a shroud does improve performance but the cost is still unproven.
Several years ago Yuji Oyha, a professor at Kyushu University, captured imaginations with his novel design for what he called a “Wind Lens.” While a giant rim-like rotating wheel for offshore energy has yet to be fully realized, several smaller experimental versions have been installed high above a park in Fukuoka, Japan -- part of a major green energy expansion in the country.
Thresher called the Wind Lens a type of wind augmenter that has some structural advantages in a smaller size. In the past he’s seen a similar device with a rim drive so all the equipment could be on the ground. The problem, he said, is that you can’t hide in high winds. Any lens-like structure has to be built to withstand them. “It might work for small devices,” he said. “Particularly if your turbine is in a low wind-speed place where the augmentation might be important.”
We’ve crossed a few odd designs off the list as too improbable to feature. Bob shoots down to a satellite-dish shaped turbine he says will wobble like a sign on the highway. But he perks up about a bladeless turbine called an Electrostatic Wind Energy Convertor or EWICON for short created by researchers in the Netherlands at Delft Technical University. A steel frame holds insulated tubes that spraying positively charged water particles into the air. As the breezes blow, the particle are driven through an oppositely charged collector array, generating a current.
“I do have doubts as to whether it can be made cost effective, and then there is the added requirement for a pure clean water supply,” he cautioned, but called the approach innovative. “This is truly a unique wind device.”