When a company sets a goal to reach zero emissions within decades, it has to start cutting carbon on every possible front. For Unilever NV, that means spending €1 billion ($1.2 billion) to help its suppliers adopt technologies to eliminate the use of fossil fuels in the production of cleaning products by 2030.

You may not associate the black gunk of crude oil with the pleasant-smelling detergents that wash your clothes, but that’s the magic of chemistry. Through a series of chemical reactions, the long-chain carbon compounds found in crude oil can be turned into chemicals capable of removing oil stains from your clothes.

Eliminating the use of fossil fuels to make those chemicals has been technically feasible for decades, but the cost has remained prohibitive. Unilever’s is the first large investment in a sector that has finally begun looking to replace oil in its production process with ingredients derived from wood or microbial fermentation, or even recycled carbon from other industries.

“What Unilever is trying to do is very comprehensive,” said Katy Armstrong, a researcher at the University of Sheffield who works on reusing carbon. “With great ambition, it is looking at the entire supply chain.”

In June, the consumer-goods giant set a target to cut all emissions from its operations and its suppliers by 2039. The company wants to reach this milestone with minimal use of carbon offsets, which are cheap to buy but don’t always do what they promise. Because 30% of the company’s annual emissions come from suppliers, it can reach its goal only by requiring suppliers to cut the use of fossil fuels. About 65% of Unilever's emissions come from customers using its product, and the company hasn't set a firm reduction target on those.

The work to eliminate fossil fuels from cleaning products began in 2018, says Ian Howell, who leads Unilever’s research team studying advanced materials for homecare products, including the brands Persil, Cif, and Domestos. At a company event, Howell heard the chief executive of Seventh Generation, which Unilever acquired in 2016, talk about how all its cleaning products come from plant-based sources. Employees asked Howell whether all of Unilever’s products could do the same. “That’s not affordable or sustainable,” said Howell, “because there’s not enough [natural resources] to make that switch.”

Howell commenced working with his team to find all the non-fossil fuel carbon sources they could put to work. The result is what Unilever calls a “carbon rainbow.” Purple is for carbon dioxide captured from the air or from industry; blue is derived from marine sources; green from plant sources; grey from recycling plastic; and black from fossil fuels.

The task for Howell’s team now is to convert Unilever’s factories to be able to use these alternative sources. The $1.2 billion will go toward research, implementation, and working with suppliers. Depending on the local resource availability, the “color” of carbon used may vary, but black carbon is to be eliminated within a decade.

Those products may still come in plastic packaging, which is currently derived from fossil fuels and which Unilever is looking to clean up in a separate effort. But Howell said Unilever’s fossil fuel-use associated with cleaning chemicals is currently higher than that associated with its plastic production, anyway.