

There are a myriad of reasons why high energy prices are bad for economic growth but the impact on productivity growth is, in my opinion, one of the key ones.
When oil prices shoot up, firms are forced to invest in schemes to reduce their oil consumption, at the cost of other investments.
Say a factory has $50,000 to either buy a new radiator or a new conveyor belt. In a world of low energy prices, the company would buy the conveyor belt and increase production. In a world of high energy prices, they company has to buy the heater, depriving them of the capital necessary to expand production. Multiply this by tens of millions of businesses and the world gets poorer.
To make matters worse, the impact is asymmetrical. People (at least historically) tend to overreact to high oil prices and make a lot of bad investments out of fear. Incidentally, the same happens with taxes/subsidies. Lots of people bought cars they couldn't afford to take advantage of a small tax credit under the Cash For Clunkers program.