Representational image.

Joe Brock, Yuddy Cahya Budiman, John Geddie and Valerie Volcovici, Reuters

The global consumer goods industry’s plans for dealing with the vast plastic waste it generates can be seen here in a landfill on the outskirts of Indonesia’s capital, where a swarm of excavators tears into stinking mountains of garbage.

These machines are unearthing rubbish to provide fuel to power a nearby cement plant. Discarded bubble wrap, take-out containers and single-use shopping bags have become one of the fastest-growing sources of energy for the world’s cement industry.

The Indonesian project, funded in part by Unilever PLC , maker of Dove soap and Hellmann’s mayonnaise, is part of a worldwide effort by big multinationals to burn more plastic waste in cement kilns, Reuters has detailed for the first time.

This “fuel” is not only cheap and abundant. It’s the centerpiece of a partnership between consumer products giants and cement companies aimed at burnishing their environmental credentials. They’re promoting this approach as a win-win for a planet choking on plastic waste. Converting plastic to energy, these companies contend, keeps it out of landfills and oceans while allowing cement plants to move away from burning coal, a major contributor to global warming.

Reuters has identified nine collaborations launched over the last two years between various combinations of consumer goods giants and major cement makers. Four leading sources of plastic packaging are involved: The Coca-Cola Company, Unilever, Nestle S.A. and Colgate-Palmolive Company. On the cement side of the deals are four top producers: Switzerland’s Holcim Group, Mexico’s Cemex SAB de CV , PT Solusi Bangun Indonesia Tbk (SBI) and Republic Cement & Building Material Inc, a company in the Philippines.

These projects span the world, from Costa Rica to the Philippines, El Salvador to India. In Indonesia, for instance, Unilever is partnering with SBI, one of that country’s largest cement makers.

The alliances come as the cement industry — the source of 7% of the world’s carbon dioxide emissions — faces rising pressure to reduce these greenhouse gases. Consumer brands, meanwhile, are feeling the heat from lawmakers who are banning or taxing single-use plastic packaging and pushing so-called polluter-pays legislation to make producers bear the costs of its clean up.

Critics say there’s little green about burning plastic, which is derived from oil, to make cement. A dozen sources with direct knowledge of the practice, among them scientists, academics and environmentalists, told Reuters that plastic burned in cement kilns emits harmful air emissions and amounts to swapping one dirty fuel for another. More importantly, environmental groups say, it’s a strategy that could potentially undercut efforts spreading globally to boost recycling rates and dramatically slash the production of single-use plastic.

Such thinking is naive, said Axel Pieters, chief executive of Geocycle, the waste-management arm of Holcim Group, one of the world’s largest cement makers and partner with Nestle, Unilever and Coca-Cola in plastic-fuel ventures. Pieters told Reuters that burning plastic in cement kilns is a safe, inexpensive and practical solution that can dispose of huge volumes of this trash quickly. Less than 10% of all the plastic ever made has been recycled, in large part because it’s too costly to collect and sort. Plastic production, meanwhile, is projected to double within 20 years.

“Thinking that we recycle waste only, and that we should avoid plastic waste, then you can quote me on this: People believe in fairy tales,” Pieters said.

Unilever would not comment specifically on the Indonesia project. It said in an email that in situations where recycling isn’t feasible, it would explore “energy recovery initiatives.” That’s industry parlance for burning plastic as fuel.

Coca-Cola, Unilever, Colgate and Nestle did not respond to questions about the environmental and health impacts of burning plastic in cement kilns. The companies said they invest in various initiatives to reduce waste, including boosting recycled content in their packaging and making refillable containers.

Cemex, SBI, Republic Cement and Holcim’s Geocycle unit told Reuters their partnerships with consumer goods firms were aimed at addressing the global waste crisis and reducing their dependence on traditional fossil fuels.

Exactly how much plastic waste is being burned in cement kilns globally isn’t known. That’s because industry statistics typically lump it into a wider category called “alternative fuel” that comprises other garbage, such as scrap wood, old vehicle tires and clothing.

The use of alternative fuel has risen steadily in recent decades and already is the dominant energy source for the cement industry in some European countries. There’s no question the amount of plastic within that category has increased and will keep climbing given a worldwide explosion of plastic waste, according to 20 cement industry players interviewed for this report, including company executives, engineers and analysts. Reuters also reviewed data from cement associations, individual countries and analysts that confirmed this trend.

For example, Geocycle currently uses 2 million tonnes of plastic waste a year as alternative fuel at Holcim plants worldwide, according to Geocycle CEO Pieters, who said the company intends to increase this to 11 million tonnes by 2040, including through more partnerships with consumer goods companies.

Pieters said the cement industry has the capacity to burn all the plastic waste the world currently produces. The United Nations Environment Programme estimates that figure to be 300 million tonnes annually. That dwarfs the world’s plastic recycling capacity, estimated to be 46 million tonnes a year, according to a 2018 estimate by the Organisation for Economic Co-operation and Development (OECD), a global policy forum.

Plastic pollution, meanwhile, is bedeviling communities whose landfills are reaching capacity and despoiling the Earth’s wild places. Plastic garbage flowing into the oceans is due to triple to 29 million tonnes a year by 2040, according to a study published last year by the Pew Charitable Trusts. This detritus is endangering wildlife and contaminating the seafood humans consume.

“The cement industry is definitely a solution,” Geocycle’s Pieters said.

Consumer goods giants are turning to cement firms for help in reducing plastic litter as other initiatives stumble. Reuters reported in July that a set of new “advanced” plastic recycling technologies promoted by big brands and the plastic industry had suffered major setbacks across the world.

Cement-making is one of the world’s most energy-intensive businesses. Fuel — mainly coal — is its single-biggest expense, industry executives said. In the 1970s, producers looking to reduce costs began stoking kilns with rubbish such as tires, biomass, sewage sludge — and plastic. Those materials aren’t as efficient as coal, but are virtually free. Some local governments even pay cement makers to take this waste.