Is 'green' power money misguided? Market is booming, but dot-com memories make some worry

Long considered marginal and even quixotic, energy from sources like the wind, sun and plants is turning into one of the world's most highly valued industries. And while power generated by ''green'' sources remains tiny compared with fossil fuels, the sector has begun to attract the attention of big-league investors seeking to profit from a new wave of growth in alternative energy.