Please Don’t Eat the Diesel Substitute
WHY YOU SHOULD CARE
A good biofuel is hard to find.
If you can call a 50-foot tree a weed, then Croton megalocarpus pretty much qualifies. Millions of the sparse, spindly giants litter the fields and villages of East Africa, relentlessly sprouting wherever they can put down roots, their ubiquity surpassed only by the near-total uselessness of their fruit. The average croton tree produces roughly 50 pounds of nuts annually. The croton nut is inedible. As medicine, it’s next to worthless. Only thing it’s ever been good for is, literally, chicken feed.
But croton (it rhymes with “proton”) may be ready for its close-up. It’s one of several inedible nuts that just might crack the problem of producing sustainable fuel for Africa and boosting local economies without trouncing the environment. The idea is simple: Shell the nut, which looks like a rough-and-tumble cousin to the macadamia, squeeze out its oil, and presto! You’ve got a diesel substitute for vehicles and generators. The trees already cover Kenya, Tanzania and nearby countries, so there’s no initial need for large new plantations. Since croton nuts don’t end up on anyone’s dinner table, using them to make fuel runs little risk of sending more kids to bed hungry.
Work with croton is still in its infancy; it has attracted the attention of a couple of startups, but no big companies. One of these startups, Eco Fuels Kenya, says it’s already paying 2,000 Kenyan workers, mostly women, to collect croton nuts — and that they’re earning roughly three times what they could make at other agricultural work. Croton-derived fuel is “ready for today’s infrastructure” and works with existing engines, says Myles Lutheran, Eco Fuel’s managing director. “This is real now.”
All this croton acceleration is part of a global race to supplant coal and oil with renewable plant-based biofuels that won’t belch new carbon dioxide into the atmosphere. Most current biofuels, however, have huge shortcomings — either they cost too much, they’re based on food crops we also need to eat, or their cultivation disrupts native ecosystems. (Sometimes all three.) That’s why researchers are still looking for the ideal biofuel plant. In Brazil, one candidate is the macauba, a native palm tree that produces 30 tons of fruit annually. A team from the Nairobi-based World Agroforesty Centre is studying seven different plant species in India that might have game-changing biodiesel potential.
Should croton live up to even a fraction of its potential, it could be one of the best things to happen to Africa in decades. Local biofuel for generators could provide “dramatic impacts” to rural villages that currently lack electricity and refrigeration, says Thomas Foust, director of the National Renewable Energy Laboratory’s biofuel and bioenergy program. Croton might also improve the yield of nearby fruit-bearing trees, some evidence suggests. A viable croton-nut biofuel could even be that rarest of beasts, a successful African development program — possibly even one led by private companies rather than nongovernmental organizations or government aid agencies.
It’s way too soon to tell if croton can erase bad memories of Jatropha, Africa’s would-be miracle plant from a decade ago. A Central American transplant, Jatropha could indeed survive drought and bad soil conditions as advertised — it just didn’t produce many seeds for biofuel when it did. Such failures raise the bar for companies like Eco Fuels, which is now focused on improving its efficiency and attracting investment to scale up its efforts.
Eco Fuels embraces a nutty sort of nose-to-tail strategy for croton. In small villages and towns around Nairobi, workers pick nuts from croton bushes and trees, filling big bags that the startup then hauls to a nearby factory you could think of as its croton collider. There, processing not only extracts the nut oil but also turns the leftover seed cake and husk into three additional products: organic fertilizer, chicken feed and briquettes for cooking fires. Based in a Nairobi suburb, Eco Fuels has been in the croton game for three years, but it’s still a tiny operation. Lutheran says the company doubled its revenue last year — to $75,000. Officials say they’re confident they’re building a new marketplace from the ground up.
Croton “has the potential to be a good biofuel,” although it remains unproven, says Navin Sharma, director of the World Agroforestry Centre’s biofuels program. Since good data about the nut is scarce, Sharma’s group plans to spend the next two years pinpointing where the trees grow best, figuring out how to get them to sprout faster and exploring new applications for the seeds. But all the data in the world won’t turn croton into a successful biofuel business if companies can’t surmount some basic obstacles. Just ask Christine Adamow, CEO of Africa Biofuel and Emission Reduction, a Tanzania-based startup that did croton before croton was cool (that is, back in 1998). Fourteen years and $2 million later, the company effectively surrendered and pulled out of Africa; it now studies four other inedible oil-producing plants in addition to croton, but isn’t actively pursuing any of them until it can raise more capital.
Adamow says that harvesting croton from scattered trees pushes up transportation costs considerably, making plantation-style harvesting much more attractive. Unfortunately, it takes serious green to acquire land for croton orchards, and it’s difficult to convince investors to finance projects of the necessary size in Africa. While she remains a huge fan of croton, Adamow says the economics are daunting: “Someday, someone will crack this code.”
The original version of this story incorrectly said croton nuts were used in pig feed.