Another in a series of miniprofiles of sustainability-minded people who are working to reduce humankind’s footprint on the planet. To recap, they're "mini" not only because they're short, but because all the questions are 10 words or less, and the answers are requested to match. Please, no counting.

WARREN LEON, 58, Concord Senior advisor, Massachusetts Technology Collaborative

Warren formerly was director of the state's renewable energy trust, but he's now working with the Clean Energy States Alliance on national energy-policy issues and with the Patrick administration on some international economic development activities. Warren is also coauthor, with Michael Brower, of the book "The Consumer's Guide to Effective Environmental Action," which he said is "probably the best-selling environmental advice book of the last 10 years."

Green epiphany: "The oil crises of the 1970s. It became very clear we were heading down the wrong track economically and environmentally."

Green hero: "In the Boston area, one is Marty Aikens, a business agent for IBEW Local 103. He got the first wind turbine built in Boston and he’s put a lot of effort into training union electricians in new green technologies and getting them commited to them."

A new sustainability practice you've take on: "Unplugging certain appliances like the microwave and toaster oven when not in use. It doesn’t make a big difference, but it’s easy to do."

An example of greenwashing that really bothers you: "Companies that spend more money advertising the action they took than they spent on the action itself."

What don’t people understand? "Which actions make a significant difference, and which actions only have a trivial effect."

Technology you’re most hopeful about: "Photovoltaic electricity. It's still expensive, but I hope there will be continued rapid progress."

Are we going to make it? "I don’t know, but we sure have to try."

OK, that's it. Thanks for talking with me. "Wait, you didn't ask me the other question."

Which other question? "Paper or plastic."

OK, what's the answer? "Neither, or either. It’s better to use neither when you can, but it doesn’t matter a whole lot and neither choice is significantly better."