There is a lot of noise in the plastics industry right now about chemical recycling. It is pitched as the future, the silver bullet, the technology that will finally solve the plastic waste problem. And to be fair, it is an interesting area with a genuine role to play. But here is the thing nobody shouts about loudly enough: mechanical recycling, the kind we do every single day at IPL Brightgreen, is already delivering the environmental results that chemical recycling is still promising.
So let us have an honest conversation about the two.
Chemical vs mechanical recycling: the actual difference
Mechanical recycling is exactly what it sounds like. Plastic waste is collected, sorted, washed, shredded, melted and reprocessed into pellets that go straight back into manufacturing. The polymer itself stays intact. At our Castleford site, rigid polypropylene and HDPE arrive as waste and leave as high quality recycled pellets ready to become new products. The plastic never stops being plastic.
Chemical recycling takes a different route. It breaks plastic down to a molecular level, using processes like pyrolysis or depolymerisation, turning it back into oils, gases or chemical building blocks. Those outputs then need to be refined and repolymerised before they can become plastic again.
On paper, both routes turn waste into new material. In practice, the environmental maths looks very different.
The energy question
Breaking a polymer apart at a molecular level takes serious energy. Pyrolysis typically runs at temperatures of 400 to 600 degrees Celsius, and that is before you factor in the refining and repolymerisation stages that follow. Every one of those steps carries an energy cost, and in most cases a carbon cost too.
Mechanical recycling keeps the polymer intact, which means we skip all of that. We sort, wash, granulate and extrude. It is not a low energy process by any means, and we would never pretend otherwise, but independent lifecycle assessments consistently show mechanical recycling delivering a substantially lower carbon footprint than both virgin plastic production and chemical recycling routes. When the polymer does not need rebuilding from scratch, the planet does not pay for the rebuild.
The yield question
This is the part of the conversation that often gets skipped. When you put a tonne of plastic through a mechanical recycling process, the majority of that material comes out the other side as usable pellet. Losses happen, of course, through contamination and washing, but the conversion rate is strong and proven.
Chemical recycling yields are a different story. A significant proportion of the input material can be lost as gases, char or fuel fractions that never become plastic again. Some of it is burned to power the process itself. So when you hear that a tonne of waste went into a chemical recycling facility, it is worth asking how much of that tonne actually came back out as food grade polymer, and how much quietly became fuel.
If the goal is a genuinely circular economy, keeping material in the loop matters. Mechanical recycling keeps more of it there.
Proven at scale, today
Perhaps the most important point of all: mechanical recycling is not a pilot project or a press release. It is a mature, commercially proven industry operating right now, at scale, across the UK and beyond. At IPL Brightgreen, waste polypropylene and HDPE that might otherwise head to incineration, or landfill is being remanufactured into new products as you read this.
Much of the chemical recycling sector, by contrast, is still working through pilot plants, demonstration facilities and scaling challenges. The technology may well mature, and we hope it does, because hard to recycle films, flexibles and heavily contaminated plastics need a solution that mechanical recycling cannot always provide. But betting the future of plastics circularity on technology that is not yet delivering at scale, while proven infrastructure sits ready to grow, does not feel like sound environmental policy to us.
The transparency question
One more thing worth raising, because credibility matters in this industry. Recycled content from mechanical recycling is straightforward to verify. The pellet is made from waste plastic, full stop. Chemical recycling often relies on mass balance accounting, where recycled and virgin feedstocks are mixed and the recycled content is allocated across products on paper. There are legitimate arguments for mass balance as a transitional tool, but it does make claims harder to scrutinise. When a brand tells its customers a product contains recycled plastic, we think that claim should be as solid and traceable as possible.
So is chemical recycling the enemy?
No, and we want to be clear about that. This is not a turf war. Chemical recycling has a genuine role for the plastics that mechanical processes struggle with: multilayer films, heavily degraded material, complex laminates. A sensible waste hierarchy uses every tool available.
But the hierarchy matters. Reduce first. Reuse where possible. Then recycle mechanically, because it is the lowest carbon, highest yield, most proven route back into the loop. Chemical recycling should be the safety net for what mechanical recycling cannot handle, not the headline act.
What this means in practice
Every tonne of rigid PP and HDPE that comes through our doors at Castleford is a tonne that avoids virgin polymer production, avoids incineration, and stays in productive use. No molecular gymnastics required. Just sorting, science, good engineering and a team that genuinely cares about doing this properly.
The environmental case for mechanical recycling is not a projection or a promise. It is happening, measurably, every day.
If you would like to see how it works, or talk about what recycled PP and HDPE could do for your products, we would love to hear from you.
