At a factory in Vietnam, workers load rolls of undyed polyester into a steel container connected to a storage tank that holds carbon dioxide. When pressure in the container is turned up, the CO2 takes on the properties of both gas and liquid, and in turn, develops a superpower: the ability to dissolve the dye. The factory, which uses technology supplied by Dutch start-up DyeCoo Textile Systems, is making clothes coloured by carbon dioxide.

DyeCoo says its process for getting colourants onto fabric doesn’t use any water or bonding chemicals — water is still needed for rinsing, though — and can halve a factory’s typical water use and emissions from textile dyeing. (About 95 percent of the CO2 can also be recycled between jobs.) Since 2010, the company has been working with garment makers in Taiwan, the Netherlands and Southeast Asia, and its backers include Nike Inc.’s venture arm and Ikea.

DyeCoo is one of several start-ups exploring new ways to dye textiles. While the fashion industry gets flak for producing cheap clothes, burning unwanted stock, relying on plastic-based materials and shipping goods around the globe, the energy-intensive dyeing process is one of its most intractable challenges. A recent report from the industry group Fashion for Good estimated that, together with fabric pre-treatment and finishing, dyeing is responsible for over half of the industry’s total emissions. As consumers and investors put pressure on apparel companies to cut back on carbon, finding a greener way to add colour could be a big opportunity.

Dyeing clothes is carbon-intensive because of what it involves and where it tends to take place. Most methods call for water hot enough to loosen fabric fibres so that they’ll accept the dye and/or hot water to scour, bleach or wash fabrics. This is all part of a textile production stage known as “wet processing,” which also includes producing patterns and finishing fabrics prior to assembly.

In the countries where most wet processing takes place — including China, Vietnam and India — coal tends to be the cheapest and most dominant source of energy. Factories rely on it, creating a vicious cycle: Cheap coal allows for cheap textile manufacturing, which creates cheap clothes, which perpetuates the need for cheap coal.

“Coal burning in factories is contributing to the continued lock-in and use of coal in countries that need to get off coal by 2030,” says Rachel Kitchin, a corporate climate campaigner at Stand.earth, which measures companies’ decarbonisation work. “It’s fueling demand and maintaining that demand in places that would otherwise be shifting away.”

According to one report from environmental consultancy Quantis, boilers running on coal and natural gas were responsible for 44 percent of the carbon footprint in textile dyeing in 2016, and electricity from coal-burning power plants accounted for another 17 percent. Textile production as a whole generates as much as 8 percent of global carbon emissions, according to the United Nations, more than shipping and aviation combined.

A 2021 report from the Apparel Impact Institute found that phasing coal out entirely would reduce emissions from textile manufacturing by 13 percent. It could also vastly improve worker safety.

But widespread adoption of electric boilers, which can run on renewable energy, is stymied by infrastructure, funding and technology hurdles. Boilers that run on biomass inputs like wood pellets, which have been adopted as a coal alternative in countries such as Cambodia, can contribute to deforestation or drive more tree plantations on land that would be better suited for agriculture, Kitchin says.

For now, start-ups like DyeCoo are trying to tackle dyeing emissions directly. In Japan, Debs Corporation says its AirDry process, which transfers dye from paper to fabric via a printer-like machine, uses up to 95 percent less water and 86 percent less energy than traditional dyeing. British start-up Alchemie Technology has a similar technique and promises equivalent reductions in energy use.

Upgrading machinery alone won’t solve textile production’s environmental issues. Many garments, including DyeCoo’s polyester, are made from synthetic fibres that are themselves derived from fossil fuels. Most textiles are also coloured with synthetic dyes, which are both fossil-fueled and major freshwater pollutants that harm human health.

That’s where entrepreneurs like Chui Lian Lee come in. After studying textile development in school, Lee was attending a bio-design program in New York when she came across a vial of fluorescent pink proteins. “It sparked this idea that proteins can be so much more than just building blocks of food,” Lee says. “Proteins in nature have incredible functionality. They create colour through protein structure.”

In 2018, Lee co-founded Werewool Inc. out of New York. The start-up is mimicking the DNA sequence of discosoma coral — which produces a bright pink protein — and then inserting it in microbes that can proliferate through fermentation. The resulting proteins are combined with proteins from agricultural residue to form coloured fibres. Werewool aims to manufacture its first batch of protein-based pink fibres by the end of this year.

Colorado-based Living Ink Technologies is also exploring new ways to make colourants. The start-up makes black powder out of biomass waste collected from companies that grow algae as a food additive. Living Ink co-founder, Scott Fulbright says they have printed two million t-shirts for Nike with the algae dye, which will also be used on Coach leather goods next year. The company is now working on additional colours.

Figuring out how to make more sustainable pigments and fabrics, and how to apply the former to the latter, is only the first gauntlet for greening textiles. Fashion relies on production that’s low-cost and extremely flexible, which can make adopting new technologies hard to justify — especially if they’re more expensive, functionally limited and not required by regulators.

“A lot of these new technologies are financially unattractive to the industry,” says Phil Patterson, managing director of UK-based Colour Connections Textile Consultancy. Dyeing facilities already operate on a razor-thin margin, he says, and it’s unclear who would pay for damaged fabrics if an untested technology fails to deliver. Industry observers also question the colour consistency and longevity of alternative pigments — criteria that contributed to synthetic pigments overtaking plant-based dyes in the first place.

Then there’s the fragmented and impermanent nature of most fashion supply chains. Unlike computer or car companies, which often have longstanding partnerships with suppliers, apparel brands routinely switch theirs around to keep up with trends like specific stitching or special dyeing techniques. That can make it difficult to build relationships that allow for investment in renewable energy or new innovations in manufacturing.

“We don’t have a set of suppliers that’s consistent year over year. It changes based on our needs,” says Jeannie Renne-Malone, vice president of global sustainability at North Face owner VF Corp. “If there was more consistency across the supplier base, that would help make progress faster.” In 2022, VF Corp. subsidiary JanSport produced an undyed backpack made from recycled fabrics.

Over the past few years, a mix of pressure from shoppers and support from NGOs has started to tilt the scale toward decarbonisation. Organisations that include the Apparel Impact Institute and Clean Energy Investment Accelerator have also partnered with companies such as VF Corp., Gap Inc. and Lululemon Athletica Inc. to influence energy policy at the government level and help factories adopt renewable energy.

“One of the biggest hurdles is the government policies and incentives for decarbonising the factories,” Renne-Malone says. Vietnam, for example, has a pilot program that would let businesses purchase electricity directly from private firms producing renewable energy, but it’s been under review for six years.

Eventually, regulation could also move the needle. The European Commission is busy drafting legislation that would hold fashion companies accountable for the environmental impact of the clothes they produce. Jana van den Bergen, a dyeing specialist at Fashion for Good, says sustainable dyeing is “moving fast, especially because regulation is coming in.”

Overcoming technological, economic, logistical and regulatory challenges will be increasingly necessary if the fashion industry is to make good on its climate goals. So will cracking the science on large-scale low-carbon dyeing for all fabrics and colours. At the moment, Living Ink’s algae-derived pigment only comes in black, and DyeCoo’s CO2 process only works on polyester. Since launching a prototype in 2010, DyeCoo managing director Kasper Nossent says the company has sold 17 machines across eight factories.

By Olivia Rockeman and Coco Liu