As part of Earth Week at MIT, we’ve looked at a few labs that are working to build a brighter and more sustainable future.
Clean water for everyone
It’s easy to take faucets and showers for granted. But one billion people don’t have access to clean drinking water at all. That number is rising fast, thanks to climate change and population growth.
According to Course 2 Professor John H. Lienhard, the solution lies in desalination and recycling used water. “The technologies around desalination have advanced steadily over the past two decades, and both costs and energy consumption have fallen sharply,” said Lienhard, who is the director of the Center for Clean Water and Clean Energy, a joint venture between MIT and the Saudi institute King Fahd University of Petroleum and Minerals. “It also carries lower environmental impact than many alternatives, such as long distance water transfers that cause rivers to run dry.”
The secret to clean water may be inside your pencil. Recent work by David Cohen-Tanugi, a Ph.D. student in Course 3, and his advisor Associate Professor Jeffrey Grossman, shows the promise of desalination filters made of graphene. Graphene is an extremely thin form of the graphite that we use in pencil leads, and it can be made by pulling at graphite with Scotch tape. Only one atom thick, graphene is nevertheless very strong, and it’s a natural filter, with holes just large enough to let water through while catching impurities.
One of Lienhard’s goals is to produce small, solar-powered devices for water purification. “The rural developing world faces an urgent need for small-scale, locally-powered water purification systems,” he said. Lienhard and other MIT researchers also analyze the efficiency of various methods of purification. These methods include reverse osmosis, which uses a filter such as graphene, and distillation, in which water is boiled and then condensed.
The air we breathe
What’s in the air? Ask an atmospheric chemist. Noelle E. Selin is an assistant professor in MIT’s Engineering Systems Division and Course 12. “My research focuses on tracing air pollution from its source to its impacts on human health,” she said. “I use computer models to better understand the fate and transport of air pollutants such as mercury, ozone, and atmospheric particulate matter.”
Selin works at the interface between research and policy. Last year, she and several students participated in the final negotiations of the Minamata Convention, a global treaty regulating mercury pollution. Selin has also co-written a role-playing game called “The Mercury Game” (available online), intended to teach players about the role of science in policy-making.
While Selin considers effects upon human health, other researchers are exploring the effects of air pollutants on the environment and climate. Chien Wang is a senior research scientist with the MIT Center for Global Change Science, and his group studies aerosols — tiny particles that drift around the atmosphere.
“Particulate matter is a major threat to the environment and to the climate system,” said Wang, citing aerosol-caused changes in visibility, clouds, rainfall, and temperature. Coal-fired power plants produce an aerosol called black carbon, which is like very fine soot. Wang’s group has found that black carbon has a major effect on rainfall patterns in the tropics.
Wang’s group collaborates with organizations such the NASA Goddard Space Flight Center and the National Center for Atmospheric Research. Like Selin, Wang relies upon both empirical data and advanced computer models.
Can scientists solve an energy crisis with fusion reactions like those in stars? That’s the mission of the MIT Plasma Science and Fusion Center (PSFC), a collaboration between five departments: physics, nuclear science, materials science, mechanical engineering, and electrical engineering.
Martin J. Greenwald is Associate Director of the PSFC. “Fusion is a form of nuclear power that has tremendous potential advantages,” he said. “The source of fuel, deuterium, is essentially unlimited and available everywhere.”
What’s more, fusion doesn’t require dangerous uranium, or produce large amounts of radioactive waste, like standard fission-based nuclear power plants. Unlike oil and coal, it doesn’t release any carbon dioxide (the primary cause of global warming). And in contrast to wind and solar power, you can do fusion anytime, anywhere, whether or not the wind is blowing or the sun is shining. In fact, fusion is how the sun shines.
So why isn’t everything powered by fusion? “The challenge is the technical difficulty of making it practical and economical,” said Greenwald. Industrial fusion is still probably many years down the road, but MIT has built what may be like the power plants of the future — an advanced fusion reactor, or “tokamak,” called Alcator C-Mod. The tokamak is like an ultra-powerful microwave, where plasma is heated to eighty million degrees while held in a toroidal chamber by strong magnetic fields.
Due to federal budget cuts, research at Alcator C-Mod was shut down during 2013, but a stopgap measure was recently introduced to keep the tokamak operational through September. According to Greenwald, “I believe that the potential benefits are so great that it has been worth devoting a life’s work to.”
Having power is not enough. It is also important to use that power effectively, and to store it when it’s not being used.
Sometimes it helps to start small. “We have been able to harness and manipulate effects at the micro and nano scale,” said Evelyn N. Wang, Associate Professor of Mechanical Engineering. “For example, we have demonstrated the use of nanoengineered surfaces to significantly improve heat transfer for steam power plants.”
Wang’s group, the Device Research Laboratory, is developing more effective ways to harness solar energy through heat. The group is also building a battery that stores heat, using nanomaterials. This device could increase the mileage of an electric car by up to thirty percent.
James L. Kirtley, Professor of Electrical Engineering, is working on power storage and efficiency from another angle. His group studies ways to improve electricity distribution, cooling systems, and batteries for renewable energy.
Edwin F. Fongang G is a first-year Ph.D. student in Kirtley’s lab. He is working on a device that allows power from a solar array to be sent straight into the electrical grid. The device is smaller and cheaper than those already on the market, allowing it to be used in smaller-scale applications.
“The thing I enjoy most from this work is the eclectic learning experience,” Fongang said. “It involves knowledge in areas such as power electronics, modeling and control, circuit design and layout, power systems, and programming.” In addition, he says the project has the potential to improve renewable energy systems. “Working to achieve this has a good feeling to it.”
Modeling the Earth
Imagine the world. Now add to your picture: economies, societies, and the environment. What will everything be like in the future?
Enter the MIT Joint Program on the Science and Policy of Global Change. It’s a collaboration between the School of Science, School of Engineering, Sloan School of Management, Economics Department, and MIT Energy Initiative. Its goal is to understand how the Earth is changing and what we can do to shape that change.
“The Joint Program uniquely brings together scientists and economists who work hand-in-hand to confront the environmental, economic, and social challenges of global change,” said Victoria M. Ekstrom, Communications Officer for the Center for Global Change Science. She said the program addresses “climate change, but also population growth, increasing food/water/energy demands.”
The foundation of the Joint Program is the MIT Integrated Global System Modeling framework (IGSM). This is an intricate system of computer models that tie together climate patterns, ecology, and human society. How are food prices tied to weather patterns? Can we balance effective climate change policy against cost? In what ways is the ocean changing, and which areas will be impacted the most? To answer these complex questions requires collaboration across many fields.
“The Joint Program is internationally known for its IGSM model, having been one of the first to integrate the human and earth systems in such a comprehensive fashion,” said Ekstrom. “It strives to be a clearinghouse for research at the Institute and beyond.” What will the future be like? If anyone can answer, it might be MIT.