To turn plants into a renewable, nonpolluting replacement for crude oil, scientists have to learn how to convert plant biomass into a building block for plastics and fuels cheaply and efficiently. In new research, chemists have successfully converted cellulose — the most common plant carbohydrate — directly into the building block called HMF in one step. This simple process generates a high yield of HMF and allows the use of raw cellulose as feed material.