Wall Street Journal: The prospects of renewable-energy companies soared with oil prices, but the global credit crunch and the easing of energy costs have brought them back to earth with a thud. Stronger players, such as Iberdrola of Spain, are buying wind farms from cash-strapped rivals. With banks reluctant to lend and their stock prices tumbling, many green-energy concerns are struggling to find the long-term funding they need to expand in a capital-intensive industry. In the past three …