HOW TO PLAY IT

By William Baldwin

Invest in environmental remediation—not just to atone for your sins as a consumer but because this is a growth industry.

As societies become wealthier, they clean up. Darling Ingredients,

based in Texas, turns things like animal byproducts and used cooking oil into things like feed and biodiesel.

Steris, domiciled in Ireland, cleans germs out of hospitals. Tetra Tech, a California firm, does consulting and engineering in water, renewable energy and environmental compliance. Clean

Harbors, based in Massachusetts, recycles motor oil, solvents and electrical equipment. Advanced Emissions Solutions, out of Colorado, makes dirty power plants, industrial boilers and water

less dirty.