China's Energy QQC

After reading about China's energy sources, I was struck by the section on biomass. I had no idea that the idea of biomass had been around for thousands of years, and that China had been utilizing it. I would like to learn more about how the crop residue can be turned into energy, aside from the traditional rural ways of just burning it.

How have they been using biomass, and how has it changed over the years? Can they bring the idea of rural cooking energy to the modern world?