Robert Lange, a retired Brandeis University professor, prepared a solar power unit to be installed on a hut in a Tanzanian village. He wants to expand the project to Masai villages. By James F. Smith, Globe Staff | March 21, 2010 Where nightfall once meant only darkness in the tiny Tanzanian island of Tumbatu, now there are 200 points of light. And Majuba Mohammed, a high school teacher, is the proud owner of one of them. He is talking excitedly by cellphone about the tiny solar panel on his roof that now charges that phone, and powers the lamp that lets his family read indoors at night. "The project is very beautiful and helpful, and it goes well,'' says Mohammed. Nearly 200 solar panels like his have been installed on roofs in the past two years in the two villages on Tumbatu, a speck of an islet a mile off the coast of the main Zanzibar island in Tanzania. These solar panels are the product of a second career's worth of vision and sweat by Robert Lange, a retired Brandeis University physics professor who helps people put science to use in one of the poorest countries in southern Africa. From a desk in his Cambridge apartment, Lange runs a minuscule nonprofit that literally trades the dark smoke of a wood stove for the clean power of sunlight. Lange doesn't give these panels away. He swaps them: Villages need to build and install four new simple but fuel-efficient cooking stoves to earn each solar unit. The premise is that households are cutting their carbon emissions by using stoves that consume one-third less wood - and thus earn a solar installation. The units charge a small motorbike battery, which in turn can power a few low-power devices. "We're trying to set up an informal carbon credit market,'' Lange said. "We're saying four stoves is worth about $130 in reduced emissions over eight or 10 years, and for 130 bucks we can buy and import a household-scale solar energy system, to give you lights, charge your cellphone, and run a radio.'' The bottom line is that villagers get a few watts of electric power, saving them costly kerosene and wood, and giving them several more hours of nighttime light for reading and working. And the vented brick stoves save trees that would have gone into smoky indoor cooking fires. Many nonprofit groups are working to improve the efficiency of wood-burning stoves, and the use of solar power in Africa has grown fitfully. What's especially innovative here is combining the two, with the goal of crafting an informal carbon trading market like the one envisioned globally to cut emissions and use more green energy. Mohammed, who says he is about 50, is coordinating the solar project in his Zanzibar community. "The villagers are now using very, very little amounts of kerosene,'' he said. Lange is quick to point out that the idea wasn't his own, but that of his friend and colleague of nearly 30 years, Robert van Buskirk, another Harvard-trained physicist who pioneered the solar panels-for-stoves program in Eritrea in the Horn of Africa. Van Buskirk, an energy-efficiency specialist with the Lawrence Berkeley National Laboratory and now at the US Department of Energy, met Lange in Cambridge, where he went to study physics at Harvard. Both were working for left-wing causes from the Sandinistas in Nicaragua to Palestinian rights and the antiapartheid campaign. And then each went on to turn talk into action in different corners of Africa: van Buskirk in Eritrea and Lange in Tanzania. Lange, who is now 72, came to Brandeis in 1965 after getting his PhD at Harvard and spending time in England as a postdoctoral fellow. He earned tenure during his years teaching theoretical physics, then moved into the field of human vision. All the while, he said with his high-pitched laugh, "I was one of your basic campus lefty activists.'' So he jumped at the chance to spend time in Africa and do more than protest. He came to Tanzania on a sabbatical in 1986-87, teaching at the University of Dar Es Salaam. And he got hooked. He met Ali Ayoub Omar, now a math professor on the main Zanzibar island, when he worked at a camp that Lange cofounded in Zanzibar to expose young people to science and technology. For seven years, he spent two months a year in Zanzibar running the camp with Omar, supported by the Rockefeller Foundation. Omar said that Lange also collected and delivered basic scientific equipment to the 120 schools in Zanzibar. They also built wells, and helped set up the Zanzibar reptile zoo and environmental education center. Lange downplays the importance of his scientific background in his work with villagers in Tanzania. "The physics is trivial,'' Lange said. Rather, it's about sharing ideas and handing over responsibility. "I know how to work with people because I know how not to be in control.'' Van Buskirk and Omar concur that Lange has been successful in Tanzania because he offers scientific expertise without imposing his ideas or making people dependent on him. "Whenever he goes to a village, he doesn't force anything on the people. The villages can decide whatever they want. If they turn down his proposal, then no problem,'' said Omar. Van Buskirk and Lange also are engaged in similar energy-efficiency initiatives in Ghana and Senegal. The projects all share the basic premise of getting villagers to earn carbon credits, mainly by building more efficient cooking stoves: "The beautiful thing is it creates a currency for incrementally solving a global problem,'' van Buskirk said. Lange now wants to expand the stoves-for-solar experiment to Masai villages in northern Tanzania and southern Kenya. The mud-and-dung Masai huts "have the worst indoor pollution than I have ever seen in the world,'' Lange said. And people in remote Masai villages have to walk up to two hours to charge their cellphones in a region with few phone lines. So the combined prospect of less-smoky stoves and having light and phone chargers at home would be a welcome breakthrough. In the early 1990s, Lange set up a nonprofit, with the grandiose name of International Collaborative for Science, Education, and the Environment, enabling him to raise money in the United States. The nonprofit never raised serious money - $160,000 in its best year - as Lange concentrated on the programs, not the fund-raising. Lange chafes in frustration over constantly having to hunt for donors and sponsors, chewing up valuable hours. For the Masai project, he has drafted a budget of $60,000. But he added with a grin, "I could really use half a million. Hey, I need millions, you know.''