This engineering lab is green and global.

From finding better ways to make and store energy to developing clean drinking water systems, Prof. Shohel Mahmud is seeking new ideas for solving some of the planet’s most pressing problems.

And he’s encouraging grad students not just to help develop those ideas but also to share challenges and propose solutions for parts of the world – including their own homelands — racked by poverty, war or other problems.

Five PhD and three master’s candidates are already working in his lab. He expects to see three more doctoral students arrive in 2015 to be co-supervised by engineering professors Mohammad Biglarbegian, Hussein Abdullah and Animesh Dutta.

Referring to U of G’s School of Engineering, Mahmud says, “This is one of the largest research groups in the school. They’re all working on cool technology.”

That technology ranges from new materials to alternative energy to tweaks in age-old concepts for water purification. But it’s all for a common purpose, he says. “What contribution can we make to a sustainable future?”

Visit the lab at one end of the recently refurbished Richards Building, and you can’t miss evidence of their projects. Those boxes and other assemblages arrayed on lab benches are prototypes for water purification and heating and cooling systems using green technology.

What looks like a Styrofoam cooler is a cooler all right – but it’s for keeping medicines rather than picnic snacks at the correct temperature.

Conventional air conditioning systems require power, of course, and emit various gases known to harm the environment, says Mahmud. This prototype runs on solar energy and can hold the temperature below -10 C – necessary for storing medicines and especially critical in hot areas from North Africa to the Middle East.

“It’s a solar thermoelectric cooler designed for refugee camps and underprivileged areas,” he says.

Thermoelectric energy – or conversion of a temperature difference to electrical energy and vice versa — is a theme running through a number of his lab projects.

He demonstrates by plugging in wires attached to a ceramic square. Almost instantly, one side of the square warms up while the other side cools down. That phenomenon affords ways to control temperature, even amid dramatic swings in desert countries from baking days to frigid nights.

Besides eliminating costly electrical generation, these solar systems dispense with moving parts and gases by relying on solid state materials or phase change materials that alternate between liquid and solid under heating or cooling.

The challenge is to find materials and systems to make solar thermoelectric more economical and efficient, says Mahmud. Without those advantages, power suppliers and consumers balk at alternative energy systems.

PhD candidate Manar Al-Jethelah works with advanced materials to improve heat storage. In her homeland of Iraq, daytime heat can reach 55 C, but nighttime temperatures drop rapidly. How to catch and hold those daytime rays for use at night? “We need to capture or store this energy,” she says.

Iraqi engineers have built solar power plants that use salts to help store heat. But they’re seeking more efficient materials and processes. “We are an oil country, but some people are trying to use renewable energy,” says Al-Jethelah.

She works with phase change materials including porous aluminum and nanoparticles that are able to store heat. Mahmud says the same principles might make phase change materials a good candidate for wall insulation to keep room temperatures constant without air conditioning.

If a temperature change involves energy transfer, so does a sound wave. “Sound is a form of energy,” says Mahmud.

One of those lab prototypes is a thermal acoustic system. Another PhD student, Shariful Islam, plugs in a device that heats and cools either end of a porous ceramic chunk held inside a glass tube. The system emits a high-pitched whine, caused by vibrations set off by that temperature gradient.

Instead of plugging in the system, someone might use a lamp or sunlight to supply energy; a magnet would help control energy output and increase the efficiency of this thermal acoustic system, he says. He imagines using such a system in medical imaging or for emitting sounds to deter pests in a farmer’s field.

Following his undergrad in Bangladesh, Islam completed an M.Sc. in optimization and control at Dalhousie University in Halifax. Here at Guelph, he’s co-supervised by Mahmud and Biglarbegian. The latter studies control of thermoelectric systems, including making computer algorithms for the controller in that medicine cooler prototype.

Also from Bangladesh, master’s student Raihan Siddique is interested in developing energy systems based on motion or vibration. “Vibration is everywhere,” he says.

For example, a farmer might capture the thrum of a tractor – or even just his or her walking motion — to power a wireless phone. The farmer might track down an individual cow in the pasture by wireless monitoring of a GPS system powered by energy from the animal’s motion.

Like Al-Jethelah, Kaswar Jamil learned of U of G’s mechanical engineering program through the Iraqi government. He was drawn by Canada’s reputation as a safe, advanced country. “Guelph is an international university,” says Jamil, now pursuing a PhD with Mahmud.

Jamil studies the use of advanced materials for solar stills, a traditional water purification method. In his homeland, both the Tigris and Euphrates rivers are polluted by various sources, including discharge from oil-based power plants. Worse, rural water treatment plants are substandard. Three out of four Iraqis lack regular access to safe drinking water, he says.

Iraqis have long used solar stills to purify their drinking water. In the engineering lab, he demonstrates how sunlight entering an angled pane of glass strikes a thin layer of water in a baking sheet. As water evaporates from the pan and then condenses into a collector, it leaves behind the pollutants.

These devices operate on housetops. Jamil is testing inexpensive materials including aluminum foam intended to speed up evaporation and yield more clean water. “I’m working to improve its productivity,” he says.

Born in Bangladesh, Mahmud came to Canada for his PhD at the University of Waterloo. He joined U of G in 2010.