Today’s green energy advocates are focused on building out renewable solar, wind and battery resources, along with the transmission and distribution systems needed to support them. 

The aim is to accomplish all this as quickly as possible, with the goal of 100% carbon-free electricity by 2035. However, it’s increasingly clear that we need to be planning end-of-life strategies for solar panels, wind turbines, batteries and even transformers, because the earliest installations could be reaching the replacement or retirement stage soon.

While this isn’t an immediate crisis, options must be developed within the next decade to meet what could become an enormous demand across several industries, considering the rapid growth of renewable and storage industries over the last 20 years. 

One primary financial driver of that performance has been the investment tax credits first introduced in 2006, with added incentives in 2009 as part of the American Reinvestment and Recovery Act during and after the Great Recession.

As a result, millions of solar panels and tens of thousands of wind turbine blades have been added to the nation’s roofs and landscapes. In the last decade, battery-based storage systems have evolved to help balance the intermittency of solar and wind. 

Transformers aren’t directly related to this growth of renewables, but this equipment is also in need of environmentally safe and financially viable recycling and disposal solutions.

End-of-life transformers

Transformers may incorporate century-­old technology, but they remain critical to the electrical transmission and distribution systems carrying power from solar, wind and storage operations, and many are aging out of useful service lives. 

The average age of installed large U.S. transformers is 40 years, which also is their expected lifespan. While they may look like big metal trashcans, they can be tricky to recycle. Liquid-filled and dry-type models pose challenges for utilities that don’t want to ship them to a landfill.

Liquid-filled models use dielectric fluid—nonconductive oil that insulates electrical equipment and resists oxidation and corrosion—to keep transformers from overheating. Unfortunately, models manufactured before 1979 might include highly toxic polychlorinated biphenyls (PCB) as additional insulating agents. 

Given the age of much of the existing transformer fleet, handling the cleaning, recycling and disposal of this oil and parts it has come in contact with represents a significant challenge. However, if PCBs aren’t involved, the oil can be recycled, along with the steel components and copper wiring.

Dry-type units pose separate recycling difficulties. These units use air circulation and specific insulation to maintain acceptable operating temperatures. However, the insulation, which can include resin to encapsulate specific components, can make recovering copper and other protected metals difficult or impossible.

Having a strong supply chain for transformer recycling services and recycled materials is becoming increasingly important, given the current global transformer shortage and the impending need to replace many of the units now in place.

Solar circularity

Some figures help illustrate just how quickly solar energy has grown over the last decade: in 2014, it accounted for less than 0.5% of total U.S. energy generation, and by the end of 2023, utility-scale installations were meeting almost 4% of the nation’s electricity demand. Regionally, that impact is significantly higher, with photovoltaic (PV) technology meeting 23% of demand in Nevada and 19% in California, according to a report by Climate Central, a climate science nonprofit. 

It’s difficult to find numbers of just how many individual solar panels are installed in the United States. News groups and researchers focus, instead, on the total capacity of panels brought into service each year. In 2023, that figure totaled nearly 33 gigawatts (GW) across residential, commercial and utility-scale markets. Considering the average utility-scale panel produces 300–500 kilowatts, that figure represents a lot of PV panels. 

About half of the country’s current 161 GW of solar capacity has been installed since 2020, according to the Solar Energy Industries Association (SEIA) and Wood Mackenzie, but with the oldest arrays now pushing 20 years old, panel recyclers are gearing up, and their biggest market for recaptured materials could be panel manufacturers. Recaptured materials include the aluminum used in frames and the glass used as a protective top (and sometimes bottom) layer, along with the silver, copper and crystalline silicon used to enable electricity generation.

Startup SolarCycle, Oakland, Calif., is one of the five U.S. companies SEIA lists as providing panel-recycling services. The company claims it is able to recover up to 95% of a recycled panel’s value. 

It’s also beginning to use some of the reclaimed material as feedstock for a new plant in Cedartown, Ga., that will recycle panels and manufacture solar glass to serve domestic PV panel manufacturers. These could include Irvine, Calif.-based Qcells, operator of the largest silicon-based panel factory in the United States. 

In February, the two companies announced a partnership, with SolarCycle recycling decommissioned Qcell panels to build a circular and sustainable domestic supply chain for panel manufacturers.

Cutting turbine blades

Like solar, wind energy has seen tremendous growth over the last decade, with the United States adding more than 83 GW of new capacity between 2014 and 2023—a 130% increase. Several states have seen even faster growth, with Texas, the nation’s wind-power leader, growing its capacity by nearly 190% over the same period, and Oklahoma and Kansas each surpassing 200% growth. 

Turbine foundations and towers can last 30 years or more, and 85% to 90% of a wind turbine’s mass is easily recyclable. However, the last 10% to 15% is problematic and primarily includes turbine blades, which age out at around 20 years, given the high exposure to heavy winds and extreme weather conditions. Each tower can go through two sets of blades during its lifetime, and the blades are very difficult to recycle. The problem lies in how the blades are made—they’re fabricated from carbon fiber and fiberglass (also found in a turbine’s nacelle and hub covers). Neither material is easy to break down and reuse, at least at this scale.

In some cases, turbine manufacturers have turned to companies promising to recycle blades that have stockpiled them instead. In September, GE filed suit with Global Fiberglass Solutions (GFS), claiming they paid the company $17 million to recycle turbine blades, but later found GFS had simply piled the blades at two locations in Texas and Iowa. 

Another GE partner, the environmental engineering firm Veolia, Boston, developed its own solution that shreds the blades down to pebble-sized bits used as fuel for cement kilns and as a raw material to replace some sand, clay and other ingredients in cement manufacturing. Analysts with Quantis, a sustainable development consulting firm, estimate these efforts would reduce carbon emissions from cement production by 27%.

Submissions close in July for the second phase of a $5.1 million U.S. Department of Energy competition for other creative recycling approaches. Winners are expected to be announced in September. One team from the University of Maine envisions a way to use blades’ shredded fiberglass as reinforcement and filler for large-scale 3D printing efforts.

Reuse and recycling

Lithium-ion batteries are the newest technology in this collection, and end-of-life approaches are still being developed for electric vehicle and stationary storage applications. In general, researchers and entrepreneurs are looking at two options: reusing or recycling. Reuse is a more feasible option for EV batteries, as several pilot efforts have incorporated these units into utility stationary storage installations. However, once batteries used in energy storage no longer meet those requirements, they’re unlikely to be usable in other settings, so recycling or disposal will likely be the only choices.

Of course, EVs and energy storage have been on a tremendous upswing over the last decade. Between 2010, when production of the first mass-market EVs began, and 2023, EVs grew to 8.1% of U.S. light-duty sales, and stationary energy-­storage systems became common add-ons to utility-scale solar and wind projects and residential rooftop solar installations. Several states are incorporating battery systems into incentive programs for home solar panels, and the Internal Revenue Service now offers tax credits for batteries like they do for PV panels.

EV makers generally offer warranties for their batteries for 8 years or 100,000 miles, and the batteries can possibly last longer. But once they reach 70% to 80% of their original capacity, replacement might be necessary. 

However, that capacity level could still be viable in utility storage applications. The batteries will need inspection and reconditioning, so it’s not a simple swap, but it can help make the most out of their lifetime energy-storage capabilities. 

Whether they are installed new or reconditioned, stationary storage batteries don’t yet have good second-life options. New startups are developing methods for recycling materials such as cobalt, lithium, nickel and magnesium for use in manufacturing new units, which could help ease today’s supply-chain snarls. These include Redwood Materials, Carson City, Nev., which is already working with several automakers and recently worked with utility Southern Co. and the Electric Power Research Institute to recycle one of the earliest utility-scale battery systems in Cedartown, Ga.