Residual Waste Finds a Second Market in Cement Kilns as Landfill Costs Climb

Tip fees above $50 per ton in many regions are the number reshaping residual economics, and the operators who will navigate the next decade best are, in the words of supply intelligence head Anna Sorokina, the ones "treating their residuals not as a disposal problem to minimize, but as a material stream to understand and place."

The context is a shrinking disposal market. New landfills are not opening; permitting timelines stretch for years and host communities push back. In much of the country, the airspace that exists today is the airspace operators will have tomorrow. As that capacity tightens, tip fees climb, and every ton of residual buried is a ton costing more to dispose of with nothing to show for it. Diversion mandates, extended producer responsibility rules and customer zero-to-landfill commitments all push in the same direction: find another home for what is left.

That home increasingly runs through heavy manufacturing. Cement, lime and steel producers burn enormous quantities of coal and petroleum coke to reach kiln temperatures, and a growing share of that fuel can be replaced with engineered fuel made from residual waste — a practice known as coprocessing with alternative fuels.

What is engineered fuel, and what does coprocessing change?

The fuel is engineered, not just collected. A producer takes residual streams and processes them into a consistent Solid Recovered Fuel (SRF): a drop-in coal replacement built to a spec, sized, dried and blended so its heat value, chlorine and ash land where a kiln needs them. Coprocessing is the industrial process of burning that engineered fuel in place of fossil fuel inside a high-temperature operation. It is not incineration, and the distinction matters.

In a cement kiln, material sees roughly 1,450°C for several seconds in a highly alkaline environment. Organics are destroyed completely, acid gases are neutralized by the process chemistry, and the mineral ash is absorbed into the clinker itself. There is no separate ash to landfill afterward. The waste delivers both its energy and its mineral content into the product — a combination of energy recovery and material recovery that makes the process more beneficial from a diversion perspective.

For the kiln operator, the appeal is cost and carbon: waste-derived fuel is typically cheaper per unit of energy than coal and lowers the plant's emissions profile. For the waste operator, it is a downstream outlet for a stream that had none.

How does the operator-side math work?

Two things change when a residual becomes fuel: what it costs and what can be claimed. Landfilled, a ton of residual carries a tip fee that in many regions now runs well north of $50 — that is more than $50,000 per thousand tons, before hauling and long-term airspace consumption are counted. It generates no revenue and no diversion credit.

Routed to a fuel outlet that accepts waste-derived material, that same ton can move at a gate fee that competes with the landfill cost, while often counting as diverted material reportable to customers. The economics turn on local landfill pricing, transport distance and the nature of the stream. The structure is straightforward: a rising, dead-end cost is replaced with a competitive one that comes with a diversion story attached.

The source advises comparing fully loaded costs on both sides — landfill tip fee plus transport plus the airspace consumed — rather than headline numbers alone.

There is also a structural advantage. Of the available diversion paths, coprocessing is one of very few that can absorb residual at the magnitude and material-movement rates these streams generate. Composting, further recycling and specialty reuse all hit ceilings; a cement kiln consumes fuel by the thousands of tons every 15 minutes. For a high-volume residual with nowhere else to go, that throughput capacity is everything.

Which streams qualify?

Coprocessing is not a home for everything. Broadly, combustible residuals tend to be good candidates, while very wet, heavily inert or contaminant-heavy streams are harder. Every stream is different, and the only way to know where one lands is evaluation by a fuel producer who can assess the specific material.

Form matters too. Kilns feed fuel through specific systems and expect a consistent product rather than loose, variable trash. In most arrangements the fuel producer handles that processing, so the operator's job is to supply the residual, not solve the fuel-engineering problem.

Where does this sit in the hierarchy?

None of this replaces recycling, and it should not. Coprocessing sits below the commodity streams already being recovered and above the landfill: a home for the hard-to-recycle fraction that would otherwise be buried. In a market with no new landfills and tightening diversion rules, that middle tier is where the industry's pressure is building.

Sorokina is Head of Supply Intelligence at Forge Industries, which is developing what it describes as the first U.S. alternative-fuel facility dedicated to cement, lime and steel coprocessing, with its Nevada plant coming online in 2027. Forge converts hard-to-recycle and residual streams into a coal displacement fuel for heavy industry, at a fraction of the emissions. The company has also released a free calculator that lets operators enter tonnage and current landfill cost to estimate annual savings and tons kept out of the landfill.

The first step, per Sorokina, is simply knowing that a second option now exists — and that someone downstream may be ready to put your residual to work.

The milestone to watch: Forge's Nevada plant coming online in 2027, which would give U.S. residual generators a dedicated coprocessing outlet for the first time.