Lightening the load: Gravity ropeways designed by Practical Action for use in Nepal
Mount Mulanje rises above the plains of southern Malawi and brings rain to the region. The elevation of the mountain – more than 3,000m – is enough for it to induce clouds to form, making it an important source of rainwater at the head of almost every river that runs through that part of the country.
Mechanical engineers are working in the area to use those rivers to provide usable energy. According to one of these, Drew Corbyn of the UK charity Practical Action, only 7-9% of people in Malawi have access to the electricity grid.
GSMA Community Power From Mobile estimates that up to 80% of households are without grid electricity. Some three million mobile-phone SIM connections are being used off-grid, says the organisation – meaning that, while many Malawians have mobiles, they do not necessarily have the means to charge them readily available.
The US aid agency the Millennium Challenge Corporation recognises that poverty in Malawi could be significantly reduced through improvements to the grid. So it has entered into a programme that could be worth more than $350 million to revitalise the country’s power sector and improve reliability and availability of supply.
Escom, the state electricity provider, has come in for heavy criticism from Malawi’s citizens for trying to raise tariffs without managing to improve services. The utility counters that higher prices are needed to allow it to invest in infrastructure. For its part, the Millennium Challenge Corporation says: “The sustainability of our work in Malawi is based on strengthening Escom’s ability to recover costs, invest in service provision and be a viable partner for investors.”
Meanwhile, engineers are also working on micro-generation projects such as the hydro scheme that Corbyn is engaged in completing in a village on the plains around Mount Mulanje. The high level of precipitation around the mountain helps, he says. “The mountain attracts huge rainfall. There are quite significant perennial rivers in the villages in the immediate surroundings of the mountain, and they run steeply.”
Practical Action’s scheme taps into the power of one of these rivers to generate 90kW of electricity. At the moment, 150 houses have been connected: the plan is for 400 to ultimately be given power, plus a clinic and schools.
“There was no power before this,” Corbyn explains. “In the houses, people would use kerosene and battery-powered torches for lighting. The school didn’t have any provision for power, and the clinic struggled. Perhaps there was a small solar panel for lighting or charging phones.
“In a country of millions, many people are living in the Dark Ages.”
Practical Action’s ethos is to use technology to challenge poverty in developing countries. The aim is to work with local people to introduce solutions that solve problems and are sustainable in the long term. If successful, those solutions can be replicated over and over again.
Corbyn’s hydro scheme uses a concrete weir that diverts a proportion of the river’s flow – even in the driest month, about 300 litres of water a second – into an open channel, which contours around the hillside. The water is then piped down a steep section at high pressure and velocity for 40m and taken into a powerhouse to drive a turbine connected to a generator. The water is then returned to the river 1km downstream.
The system is said to be environmentally benign and cheaper than small-scale wind or solar power. It is 8km from the grid.
Corbyn says: “Extending the grid is prohibitively expensive, and the performance of electricity companies in Malawi is not great. If you’re in an urban area, then you stand a better chance of gaining access, although the connection rate is notoriously slow. There are villages where there is very little hope of grid extension in the short-to-medium term.”
Engineers in Malawi are installing micro hydro power schemes for villages
In Malawi, Practical Action is working on one other hydro scheme but the systems are much more widespread in some other developing nations. Nepal, where the charity also works, has 2,500 micro-hydro mini-grids. Practical Action has also developed the systems for Kenya, Mozambique and Zimbabwe, but Bolivia and Sri Lanka have a greater number of micro-hydro schemes, says Corbyn. “Malawi and Africa are generally lagging behind.”
As well as providing energy to developing nations, British engineers are interested in the potential of liquid-air technology to improve on the scandalously high rates of food wastage. According to a report released by the IMechE last year, about half of all food produced around the world is wasted. Improvements to the ‘cold chain’ in developing countries could help to preserve more food, concluded a new study recently launched by the institution (see page 68).
This latest IMechE report estimates that 25% of food wastage in the developing world could be eliminated with better refrigeration equipment. Having a more extensive or reliable cold chain – a temperature-controlled supply chain for perishable goods – could improve domestic food supply and increase the value of exports of food from countries such as India.
A reliable electricity supply is required for the cold chain. Since connection to the grid is not a given for many in developing countries – in sub-Saharan Africa 70% of the population has no access to electricity, and in India 350 million people live in off-grid villages – renewable energy with associated storage technology should be used to develop cold chains, says the IMechE. Cryogenic energy storage using liquid air or nitrogen is one viable solution.
Dr Tim Fox, head of energy and environment at the institution, also believes that the Dearman engine, a British liquid-air innovation, could provide an alternative to vehicle refrigeration powered by diesel in developing nations and help to establish a harvest-to-marketplace cold chain.
Diesel-powered transport refrigeration units (TRUs) are inefficient and highly polluting. When diesel is used, refrigeration can consume as much as 20% of a truck’s fuel. And a TRU emits up to six times as much NOx and 29 times as much particulate matter as a truck propulsion engine designed to meet Euro 6 emissions standards.
The Dearman refrigeration unit is said to be a significant advance on current liquid nitrogen cooling systems because it produces both cooling and shaft power from a single unit of fuel. The cryogen – either liquid air or liquid nitrogen – is vaporised in a heat exchanger in the refrigeration compartment, so cooling it down. Then the high-pressure gas is used to drive the Dearman engine, whose shaft power can be used to drive a conventional refrigeration compressor or for auxiliary power.
This means it is efficient and cost-effective. It also produces zero exhaust emissions. The Dearman engine was invented by Peter Dearman and first demonstrated in a liquid-air-powered car.
Things have moved on. According to a study launched recently at the Society of Motor Manufacturers and Traders, in Britain, replacing just 13,000 refrigerated transport units with a liquid-air zero-emission solution could reduce levels of dangerous particulate matter and NOx by the same amount as taking 367,000 Euro 6 trucks off the road – more than three times the entire UK fleet.
There are more than 80,000 refrigerated vehicles on the road and this number is growing annually. Most work in urban and residential areas, where air quality is a problem. In the developing world such solutions will only appeal if they are made readily available, viewed as cleaner and made cheaper than less sustainable but better-established technologies, says the IMechE. It calls on the UK engineering community to develop the systems that could make the difference.
Toby Peters, founder and chief executive of the Dearman Engine Company, says of the technology: “If you need cold and power we’re the solution.” He acknowledges that the scope of the company’s work has broadened. “You need to think about the bigger opportunity: it’s not a niche product. Refrigeration represents a massive source of potential demand, and food is being wasted in developing nations.
“If we can use liquid air to deliver cold and power, that creates a market opportunity for Dearman and also delivers intervention in a global problem.” He emphasises, however, that the liquid-air engine is not the answer to all transport woes. “This is not a silver bullet – too many technologies say we’re the panacea.” Some now describe TRUs as the “killer app” that will take the Dearman engine into the mainstream.
Peters says: “I think Peter Dearman is a visionary who saw the potential for the technology: what we’ve done is evolve the market opportunity. When Peter invented it, people weren’t thinking about the cold chain in India. If he had invented it today, he would have taken it straight to the cold chain.”
Fox presided over a summit at One Birdcage Walk recently with the aim of disseminating the findings of the IMechE’s cold-chain report more widely. There were speakers from the Tanzania Horticultural Association and India’s Ministry of Agriculture, as well as Toby Peters and others. Fox has also travelled to India to meet engineers there. He says: “When this technology first came on the horizon, the idea that you might have taken the Dearman engine and applied it to one of these refrigeration trucks, making a solution to part of the cold chain, just wouldn’t have been on the radar. It just shows you that we have to think innovatively.”
In Europe, regulations coming in next year will create opportunities for Dearman engine-powered TRUs. Among the developing nations, in India there is perhaps most readiness for the technology, with a domestic industrial gases engineering resource up to the job and a severe problem with food wastage, says Fox. “Because sub-Saharan African countries are not as industrially advanced as India, I think it will take longer to get going there,” he says. “A success in India would act as a catalyst.
“There is more requirement in Africa for intervention by the aid community to put in place the infrastructure necessary for the liquid-air cold chain.”
Practical Action has been intervening with infrastructure projects of its own since the mid-1960s. Paul Smith Lomas, the charity’s international director, trained as a mechanical engineer in the early 1980s. He worked initially in Sudan with Voluntary Service Overseas on a refugee camp for two years and then stayed on to address longer-term development challenges.
It was the ability to make an impact on people’s lives through water and sanitation projects that appealed to him. He has worked for Practical Action, which celebrates its 50th anniversary in 2015, for four years. Engineers across the development sector refer to its textbooks, says Smith Lomas. He adds that the key is to engage local people in projects and to develop local technological solutions. “If you fly in a whole hydro power station from Norway and stick it in Malawi, the chances are it’s not right for the local context,” he says.
“If you can work with local manufacturers and adapt what they are already doing for hydro, your immediate solution is better.
“You build the solutions with the people, not for the people.”
Despite the sense of altruism that makes infrastructure projects in the developing world appealing, it is not always easy to find engineers for every job. “We can usually find qualified engineers who want to work with Practical Action but not everyone wants to go and work in some of the more difficult and remote spots,” he says. “Are there enough engineers being trained around the world? I guess the answer is no.”
Projects are piloted, proved on a small scale and, if successful, copied. The organisation’s aim is to reach six million people before 2017 as part of a five-year strategy. Two years in, it has affected the lives of two million for the better. “We need to invest in technologies that meet people’s basic needs for the long-term sustainability of the planet,” says Smith Lomas.
“At the moment we’re investing more each year in a cure for baldness than we do in a cure for malaria.”