Prices have soared: the cost of cerium oxide (often used as a catalyst) has increased sixfold since the start of the year, and is 20 times higher than in 2005.

ECONOMIST: Rare earths and China

Moreover, soil containing biochar releases less methane and less nitrous oxide than its untreated counterparts, probably because the charcoal acts as a catalyst for the destruction of these gases.

ECONOMIST: Biochar could enrich soils and cut greenhouse gases as well

One company exploits this phenomenon by making nanoparticles of the compound cerium oxide, which in that form are chemically reactive enough to serve as a catalyst.

ECONOMIST: Small wonders