As the curtain closes on 2010, we conclude another year of growth for the clean-tech industry. Much has changed since Technology Partners' first foray into clean tech in the early 1990s when the sector was branded "alternative energy," considered by most to be nothing more than pet projects for environmentalists. Over the past decade and a half, clean tech has emerged as a key driver of global economic growth and has become one of venture capital's fastest growing investment categories.