A Virgin Atlantic 747 topped off its fuel tank with the oil of 150,000 coconuts and flew from Heathrow to Amsterdam Sunday. The odor of pina coladas hanging over the economy cabin should have been a giveaway -- this idea is a stinker.

Replacing fossil fuels with plant-based biofuels is one of those ideas that sometimes sounds much better than it actually is. It's true there are benefits of biofuels. They reduce the use of petroleum-based fuels. They spew fewer toxins into the atmosphere, namely hydrocarbons and CO₂ emissions. And advanced biofuels are more beneficial still, cutting greenhouse gas emissions by at least 50%.

But it is the composition of a biofuel that determines whether it is beneficial to the environment or just a greenwash. Biofuels composed of ethanol extracted from wood waste and agricultural wastes are known as "cellulosic biomass" in the trade. These are promising.

"Three of the 747's four tanks were filled with normal jet fuel while its fourth carried a mixture that was 80% jet fuel and 20% coconut and babassu palm oil," reported the Guardian.

The agricultural economics are complicated, but I'll distill them to this: For a number of reasons, using some plants for fuel is not a necessarily "greener" practice than burning petroleum-based fuels. Food-based bio-fuels have been shown to "release 17 to 420 times more CO₂ than the annual greenhouse gas (GHG) reductions these biofuels provide by displacing fossil fuels." Crop displacement, deforestation, and increased emissions are signs of land use change that can result from a careless rush to embrace biofuels.

Virgin Atlantic's press release says that "Most coconut plantations are mature and do not contribute to deforestation." Since it took oil from 150,000 coconuts to make less than 20% of the fuel required for Sunday's flight, it's not feasible to believe that coconut oil is a solution to the planet's aviation fuel needs.

That would be nuts.