Two Laureates take on global warming’s ‘black beast’

Published in 2009

Two Laureates of the Rolex Awards will team up in a bid to devise a fast-track solution to help overcome one of the major drivers of global climate change. Their proposed collaboration has the potential to make the world far cleaner and healthier, while improving living standards for inhabitants of the poorest countries in Asia, Africa and South America.

“Black carbon”, the soot from billions of domestic cooking fires across the poorer regions of the world, is a powerful, but little-publicized driver of climate change. In underdeveloped regions, scientists now consider it is heating the planet almost as much as the CO2 from fossil fuels.

For prolific inventor Alexis Belonio and highly respected physicist Steve Garrett, this fact has created an opportunity to improve the lives and health of impoverished people, beat a major waste problem and develop a fast way to counter global warming – all at the same time.

In a marriage of engineering excellence with leading-edge science, Belonio, who was selected as an Associate Laureate in 2008 for his rice-husk stove project, and Garrett, whose plan to develop a refrigerator driven by sound waves won a Rolex Award in 1993, are looking at combining their technologies to tackle three huge problems: the greenhouse effect, the health dangers to women and children due to indoor air pollution, and energy poverty.

“Black carbon is about 600 or 700 times more potent than CO2 as a climate warmer: it absorbs more heat because it is black,” Garrett explains. “But it only lasts about 10 days in the atmosphere, so this is a problem you can actually fix quite quickly – as opposed to CO2, which hangs around for centuries.” If the smoky cooking fires of the developing world could be replaced with stoves such as Belonio’s, which converts rice husks or other biomass to a clean gas, it would cut humanity’s global warming emissions in days. Developing countries would become world leaders in combating climate change.

The challenge is to develop a stove cheap and simple enough to go into a billion homes.

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Rice husks, dumped in the countryside in many parts of Asia, are transformed into clean, efficient fuel, thanks to Belonio’s stove.
©Rolex Awards/Kirsten Holst

Belonio’s stove, now in its third generation, already fulfils most of the criteria. Fuelled by unwanted waste – the 150 million tonnes of husks discarded in rice-growing regions each year – his US$20 cooker turns this free, low-energy fuel into a gas that burns with a clear blue flame. This can save a poor family up to one-tenth of their income every year, as they no longer need to buy gas or kerosene for cooking. Because it burns cleanly, the stove is much healthier to use. The World Health Organization estimates that the indoor air pollution caused by smoky stoves kills 1.6 million women and children every year. And its greenhouse emissions are half those of fossil-fuelled stoves.

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Alexis Belonio explains the principles behind his rice husk stove at a Bangkok conference on clean cooking methods.
©Rolex Awards/Kirsten Holst

Key to efficiency of his stove is a small electric fan that drives a stream of air through the smouldering rice husks. This produces the gas mixture which the stove then burns, just like a normal gas cooker. The catch is it needs electricity to drive the fan – and half of the developing world still lacks this essential energy source.

Enter Steve Garrett, of the Pennsylvania State University, who has been working as Scientific Adviser to the U.S. State Department’s South-East Asia bureau. “We were looking for technologies that would assist development, clean up the environment, address global warming and improve health,” he says. “Alexis came to my attention through the Rolex Awards. He has generously shared all the technical details of his invention. He is working with a ubiquitous fuel. It just made perfect sense.”

What made even more sense to Garrett was that he had a clever way to turn the heat from Belonio’s stove into sound waves that could in turn be used to produce enough electricity to run the fan. It meant the stove could be used anywhere on Earth where there was a suitable fuel supply – and act as its own electrical power source.

The Laureates have agreed to explore the idea together.

Steven Garrett, 60, is a physics professor specializing in thermo-acoustics at the Pennsylvania State University. The winner of several major prizes for environmental technology and the holder of over 20 patents for his inventions, he has developed acoustics-based refrigerators for the U.S. space program, U.S. Navy and Ben & Jerry’s ice cream. His research group now works on commercial chillers and freezers, including appropriate technology for developing countries.

Alexis Belonio, 49, is animated by the ideal of sharing his stove with anyone in the world who wants it. “It is God’s calling,” he says simply. “I have received the knowledge of this stove from God for free, and I must give it for free also.” So far, more than 40 companies, non-governmental organizations, aid agencies and local groups in a dozen countries have adopted his stove design. With his Rolex Award funding, he has published a technical manual, distributed information via the Internet and run the first of a series of workshops in the Philippines to train the trainers who will distribute his technology far and wide. Belonio himself works with Minang Jordanindo Approtech in Indonesia, who are making 80 stoves a week, and plans to assist similar operations in Vietnam and Cambodia, in addition to his native Philippines. Inquiries are pouring in from countries such as India and China, as well as South-East Asia.

Belonio is now working on his Phase 3 model stove. In this model, a container of rice husks is loaded into the stove and burned until used up, then exchanged for another, like swapping the bottles on a gas barbecue. The aim, he explains, is to make the rice cooker available in towns and villages where rice is not produced locally. This will create jobs for workers in rice areas who will gather the unwanted rice husks and pack them into fuel containers. It will also greatly increase the places the stove can be used – and provide a new, low-cost cooking fuel for urban families. The ash from the burned husks can be mixed into soil, where its ability to hold moisture results in crop yields 10 to 20 per cent higher.

But what could extend the stove’s application worldwide would be the addition of its own power source, as Garrett points out: “Take a look at the dark areas of the planet at night. They are the areas where there is no electricity, where people burn biomass to cook on or warm their homes. That is where most of the black carbon comes from. In most of Asia, unlike the developed world, one half of the global warming potential is due to black carbon and other products of incomplete combustion such as methane, carbon monoxide and ozone precursors.

“It is also a big deal using a simple stove to put electricity into people’s lives in areas that may never be on the grid. They can also use it to charge a battery to light their home, or to power a cell phone.”

Working from the meticulous details that Belonio has publicized, Garrett considers it is possible to convert heat to sound, and sound to electricity, in essence reversing the process of his acoustically-powered fridge. “All you need is 2-3 watts to run the stove’s fan and a few watts more to run other devices. We would like to use the stove’s heat – the hottest heat possible – to generate sound and use that sound in a linear alternator, a sort of highly efficient microphone, to make electricity.”

There are other ways to turn stove heat into electricity, he adds – using thermoelectric methods or co-generation of steam to run a micro-turbine. They all need to be explored.

Belonio is apprehensive about the possible cost of the upgraded stove. He has struggled for years to design the cheapest, most practical stove possible, which can be made in an ordinary village workshop from scrap metal and is affordable to the poorest of the poor. He has got the price down to $20-$25 a unit, and is worried about the added cost that a high-tech power source might involve. “I’m dealing with the household sector,” he says. “They want to save their money.”

Garrett claims that it is possible to produce electricity thermoacoustically with inexpensive components. If it can be shown to work successfully and also fixes the black carbon issue, governments and aid agencies will be interested in providing funding to make the stove affordable for worldwide distribution, possibly offsetting part of the additional cost with carbon credits. He is offering the state-of-the art instrumentation of his lab at Penn State to assist Belonio in designing the most efficient and cost-effective small-scale electrical generator possible that will work with his stove.

The teeming mind of Alexis Belonio never rests. He is well advanced in the design of a super-burner that produces a far hotter flame by injecting steam. This could be used to provide boilers and dryers for small industry, fire kilns and bakery ovens or produce electricity on a scale ranging from a single household to one megawatt.

Garrett adds: “The world needs technologies that will help economic development, improve people’s health, clean up the environment, and address global warming. This partnership looks to us like a win-win-win-win situation. That’s the upside.

“The big challenge is, you need to do it a billion times,” he admits. “We have to get this technology out to 3 billion people who are burning biomass, more than half of whom have no access to electricity. The challenges of low-cost manufacturing, distribution, adoption, and marketing seem more daunting to me than the technological challenges.“ As he sees it, the task also involves developing a technology roadmap that governments can support to do the research necessary, to put clean, self-powered, fuel-efficient stoves in hundreds of millions of homes.

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Rice terraces, like these in the Philippines, provide the staple food for much of Asia. Soon the waste from rice could also provide clean energy to fuel Asia’s kitchens.
© Rolex Awards/Stefan Walter

The two Laureates discussed their collaboration at a conference organized by Garrett and two of his colleagues from the State Department in Bangkok in mid-November 2009, where tests on seven low-polluting stoves found that Belonio’s stove had the lowest black carbon emissions. To an outsider, the blue flame was indistinguishable from that produced by a natural gas or LPG stove.

The combination of Belonio’s stove and Garrett’s thermoacoustic technology could begin to help cool the planet within a decade.

Both men agree that this technological marriage would never have become possible without the Rolex Awards for Enterprise.

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