German research institute DIW sees oil prices doubling to 200 usd per barrel within the coming 10 years, DIW's head of department for energy, transport and environment Claudia Kemfert told Berliner Zeitung. "Oil reserves are becoming scarce, and that will drive up prices further," Kemfert told the newspaper. Within five years, oil prices will likely reach 150 usd per barrel, she said. But she also said a recent spike to a record level of 100 usd per barrel was largely due to speculation. "The share of the oil price that is derived from speculation is around 20 pct," Kemfert said. "An easing of oil prices cannot be expected in coming weeks. I expect in the short time an increase to 105 usd."