Managing Solid Waste Challenges in the Energy Transition

Originally published in Public Utilities Fortnightly.

The transition to sustainable energy in the United States is reshaping how we create, store, and use energy – especially electricity – and the landscape is changing rapidly.  This shift introduces new waste management challenges for utilities that require proactive planning, strategic solutions, and a thorough understanding of regulations to ensure compliance and avoid costly missteps.

As fossil-fired generation units retire and energy demand grows steadily, utilities are turning to renewable sources like wind and solar at an unprecedented scale.  The pace of change may vary in response to government policies, market conditions, and consumer preferences, but we expect the overall trend to continue.

Swapping some of our traditional electric generation for new sources will drive changes on many fronts.  This article highlights some of the challenges for solid waste management as regulated under the Resource Conservation and Recovery Act (RCRA).

Decommissioning Old-School Power Plants

Dismantling large, coal-fired power plants is no simple task, and it can generate a large volume of solid and hazardous waste.  Here are some considerations to minimize cost and stay in compliance:

Minimize hazardous waste: Hazardous waste disposal is expensive compared to ordinary construction debris.  The volume of hazardous waste generated can be reduced by managing chemical inventories ahead of time to minimize excess quantities on hand.  Any usable products can be sold or repurposed, remaining mindful of EPA’s admonition not to engage in sham transactions intended more to avoid disposal costs than to sell a valuable product.

Plan to minimize hazardous waste obligations: Under normal operating conditions, power plants often do not produce enough hazardous waste to invoke burdensome large quantity generator regulations under RCRA.  Demolition, however, can generate an amount that exceeds the large quantity threshold.  

Fortunately, EPA’s episodic generation regulations allow one hazardous waste disposal event per calendar year – and a possibility of a second event – without invoking large quantity status.  The planning process should account for episodic generation requirements.

Watch for coal ash: Coal ash can be effective in certain construction applications, and it was historically abundant at coal-fired power plants.  However, EPA now regulates structural fills of coal ash on plant sites as “coal combustion residual (CCR) management units.”  These CCR regulations may apply if the plant ever used coal ash for fill or as a foundation material.

Wind Energy and Solid Waste

Like anything else, windmills do not last forever, and the number of windmills at the end of their useful lives is growing.  Recycling and disposal of many windmill parts are straightforward. Typically, the foundation is concrete; the post is steel; and the generator parts (steel, copper wire, electronics, gears, et cetera) are familiar.

But the signature element – the blade, which can range from one hundred sixty-five feet to two hundred ninety-five feet in length – is often not recyclable.  Blades are typically made of fiberglass and resin and can be difficult to repurpose. 

In the future, manufacturers may design blades with more planning for end-of-life repurposing.  For now, utilities may need to build into their plans a process for breaking down and disposing of them, at least as a worst case.

Estimates of total disposal volumes vary but are likely hundreds of thousands of tons per year now and will rise to the millions in the coming years.  Disposals at this pace are not necessarily unmanageable nationally, but transportation costs for solid waste can be sensitive to distance, so decommissioning a wind farm may squeeze local landfill capacity.

Batteries and Solar Panels

Solar-powered generation continues to grow, and utilities are likely to install batteries on a large scale to smooth the intermittent availability of wind and solar.  The specific materials for construction vary between solar panel and batteries, but both can include a hodgepodge of rare substances such as lithium, cobalt, rare earth metals, and so-called conflict minerals.  These materials can be both valuable and difficult to manage when disposed of, so there are good reasons to recycle.

Nevertheless, extracting high-value substances from product components is often easier said than done.  The process typically entails shredding and sorting the parts.  For now, at least, this is difficult to do efficiently.  The products are designed and manufactured in diverse ways, and complexity makes recycling harder and more expensive. 

By comparison, lead acid batteries are a recycling success story because lead and sulfuric acid are valuable and easy to recover, and after several decades, the process is predictable.  Greater standardization of solar panel and battery components may enhance recycling, but for now, disposal is often more cost-effective.

Supply chain considerations may spur at least two trends.  First, concerns about reliance on foreign supplies of critical inputs may lead to efforts to enhance recycling to improve domestic availability.  Second, the same concern may lead to an increase in domestic mining and production, which inevitably presents additional waste management challenges.

Solar panels traditionally have been made of glass.  Tempered glass is recyclable but separating it from the other components may introduce complexity.  Disposal is not necessarily technically difficult if hazardous materials are stripped away, but glass is heavy, which adds to the cost of transportation and landfill tipping fees.

Vendors from waste and recycling stalwarts, to mining companies, to startups are exploring new ways to find and realize value from used batteries and solar panels.  Utility-scale retirement projects may benefit from casting a wide net for solutions and thinking creatively.

Parting Thoughts