The sun sets behind the turbines of Elk River Wind Project in Kansas. Photo by Mark Thiessen, National Geographic.

On the road to more sustainable, clean energy, the ride has been bumpy. That’s the message to two reports this week—one from the International Energy Agency and one from the Pew Environment Group—that measured progress on transitioning from fossil fuels to clean energy.

Renewable energy has stalled, both analyses point out, for a few different reasons. A big one was the global recession, not helped by enduring low cost of fossil fuels compared to cleaner alternatives. But chiefly, it’s a result of a lack of global investment in new energy research to bring down the cost of still-expensive technologies