At about $50 a barrel, crude oil prices are down by more than half from their June 2014 peak of $107. They may fall more, perhaps even as low as $10 to $20. Here’s why. U.S. economic growth has averaged 2.3 percent a year since the recovery started in mid-2009. That’s about half the rate you might expect in a rebound from the deepest recession since the 1930s. Meanwhile, growth in China is slowing, is minimal in the euro zone and is negative in Japan. Throw in the large increase in U.S. vehicle gas mileage and other conservation measures and it’s clear why global oil demand is weak and might even decline. At the same time, output is climbing, thanks in large part to increased U.S. production from hydraulic fracking and horizontal drilling. U.S. output rose by 15 percent in the 12 months through November from a year earlier, […]