Assistant Professor of Economics Nicholas Kacher California’s rising summer gasoline prices on KVCR, an NPR affiliate radio station. Kacher says that OPEC, the group of countries that produces one third of the world’s oil, “purposefully limit[s] the amount of oil that they supply onto global markets in order to keep prices relatively high.” He adds that large-scale federal investment in renewable energy sources, such as wind and solar power, would make these alternative sources more competitive with fossil fuels.