EUPHORIA ABOUT EUPHORBIA

No, they won't: They have already thought of it.

Melvin Calvin of the U. of Calif. at Berkeley, who won a Nobel Prize in 1961 for his unraveling of the complex chemistry of photosynthesis, has pointed to two species of shrubs, Euphorbia lathyrus (gopher plant) and Euphorbia tirucalli, a much larger bush that grows well in Southern California. The milky sap of these plants (and possibly 2,000 others that are about to be explored, says Calvin) is an emulsion of hydrocarbons in water. The sap, called latex, is similar to that of the rubber tree, except that the hydrocarbons in rubber latex have a much higher molecular weight. The hydrocarbon molecules in the Euphorbia latex have a size distribution very much like those in petroleum, so that after separating them from the water (by available technology), they could probably be refined into gasoline and other petroleum products in present refineries.

The plants would simply be cut near the ground and crushed in a mill much like sugar cane; what would be obtained after the water has been removed is a crude oil void of sulfur and other contaminants. Calvin estimates the cost between $3 and $10 a barrel.

And there is more good news. For one thing, the Euphorbia plants grow well in dry regions on land too poor for growing food; for another, they regrow from the stumps after cutting, so that replanting them might be necessary only once every 20 years or so.

Nevertheless, the euphoria about Euphorbia may be premature. Apart from the fact that a research program is needed to establish the definite potential of the plants, there is at least one drawback, the usual one with what is basically solar energy: the requirement of large land areas. Calvin estimates that the cultivated plant would yield between 5 and 25 barrels of crude oil per acre per year not exactly efficient land use.

But there are consolations. One is that while growing petroleum in bushes may not be ideal for the US, it may be just the thing for countries like Brazil, which is rich in other resources, but poor in energy. Euphorbia tirucalli grows well there and has been used as a hedge both between fields and for Brazil's energy bets: The Brazilian national petroleum company, Petrobras, is now investigating the shrubs in a massive program, and in another two or three years we should know all about them.

The other consolation is that just for fuel, one does not need to grow plants with learned Latin names; just about any fastgrowing, woody plant will do. Historically speaking, it is a technique far more American than -apple pie. But when it comes to feedstocks for plastics and other products of the petrochemical industry, the euphoria about Euphorbia may yet turn out to be justified.

[More: Science, 1 Oct. 1976; Proc. Centennial Meeting Am. Chem. Soc., New York 1976 (to be published)].