Oil and gas companies are used to taking big risks, but they’ve also grown accustomed to large payoffs. That paradigm doesn't necessarily translate easily to the renewables market, where relatively low risk translates to low, but mostly guaranteed, returns. “That’s the key pushback we get when we speak to companies like ExxonMobil, Total or any of the oil and gas majors,” said Tom Heggarty, a senior solar analyst at Wood Mackenzie Power & Renewables and the author of a new report assessing the place for majors in clean energy.