Peter Harriott ’49 ChE is 79 years old, and there’s a walker parked in his Olin Hall office, but don’t let it fool you: it’s just to keep him mobile until he recovers from his second knee replacement. A founding member of the Cayuga Trails Club, the emeritus professor of chemical engineering is an avid outdoorsman who loves to introduce newcomers to Tompkins County’s lesser-known hiking gems. “It’s fun,” he says, “to explore something where there’s no steps and no hand rails.”

Three decades ago, Harriott earned a bit of chemical engineering immortality by penning “The Reynolds Number Song,” a folk ditty about the formula that characterizes the turbulence of a fluid. The chorus goes like this: Take a D times a V, a rho by mu, Put them all together with a little bit of glue, Then you’ll have a number that will see you through, And tell you what the fluid’s going to do “There are four verses,” he says with a smile, “and by the time I’ve gone through the first two, I can usually get the students to sing along.”

Harriott’s other great passion marries his abiding interests in science and the environment: he’s determined to spread the word about the dangers of global warming. His mission is no passing fancy sparked after a viewing of Al Gore’s 2006 documentary An Inconvenient Truth; Harriott has been advocating conservation for decades and taught a pioneering course on synthetic fuels during the first oil crisis of the mid-1970s. “I’m trying to make people aware of the urgency,” says Harriott, who celebrated Earth Day ’07 by giving a public lecture on the subject at an Ithaca church. “People who talk about alternative energy and sustainability say ‘We’ve got wind and solar and ethanol.’ But wind, for example, contributes only half a percent of our electricity, and it will only contribute a couple of percent in 10 years. We should be doing more conservation, which has the more immediate effect of changing people’s habits.”

Soft-spoken and good-natured, Harriott is no one’s idea of a radical;  he isn’t aiming to ban cars and go off the grid. He’s a realist who knows that to protect the environment over the long term, changes must be both meaningful and livable. He advocates tougher mileage standards for cars, regulations against energy-hogging appliances, and subsidies for Earth-friendly technologies like compact fluorescents. Voluntary conservation is all well and good, he says, but it has its limits.

“The government has to take more steps,” he says. “There are Energy Star appliances, but right next to them you can buy ones a little cheaper that use more electricity, and unfortunately some people look at the first cost rather than the long term. We are responsible for so much more CO2 per capita than any other country, we have a moral responsibility to do more than let capitalism do its thing.”

Harriott has been retired since 2001, but he still comes into the office three or four times a week and gives guest lectures in several courses, including the air pollution class he founded decades ago. He has written or co-written three books, including four editions of the textbook Unit Operations of Chemical Engineering, with Cornell Emeritus Professor Julian C. Smith. Beginning this fall, fellowships in his honor will be available to Master of Engineering students in the area of sustainable energy systems and environmental protection.

Born in Ithaca to two Cornell alumni—his father studied agricultural economics, his mother home economics—he moved to Massachusetts as a child and returned to the Hill for the five-year B.S. program in chemical engineering. He earned his Ph.D. from MIT, bookending his graduate work with stints at Dupont and General Electric. “I didn’t want to be a professor who was teaching engineering design but had never designed anything,” he says. “I’ve always enjoyed the chance to combine the theoretical aspects of chemistry and engineering with the practical aspects of equipment design and operation.”

Harriott and his wife, Mary Lou, met in the Adirondack Mountain Club; they’ve been married for 53 years and have five sons and seven grandchildren. All of their sons studied engineering—four at Cornell, a rebellious fifth at Princeton—and two are now medical doctors, while the others are engineers: one electrical, one mechanical, one chemical.

A guitar player and bass singer, Harriott seeks out a community chorus at each of his sabbatic locales. He’s also a veteran woodworker, who helped build his family home. It isn’t some ultra-efficient dwelling built into a hillside but a conventional house where he has installed extra insulation and compact fluorescent bulbs, with air conditioning in only one bedroom and a thermostat kept low in the winter. “We have a clothes dryer,” he says, “but we also have a clothes line.”