The number of active municipal solid waste landfills across the country have been falling over the past few decades—from nearly 8,000 in 1988 to less than 2,000 by the mid 2000s. On the small side, a landfill is about 40 acres, which means there are at least 3.2 million acres of space going to waste (literally) in the U.S. We can also add other waste and brownfield sites, such as wastewater treatment plants and closed airports, to the list of land that is difficult and expensive to utilize and develop for other purposes.
There’s no longer a debate to the question of what to do with these sites, because it’s a simple answer: install solar panels on them.
Here’s Why Solar Landfills Make Sense
Landfills and their buffer lands make especially compelling locations for solar projects because they are generally close to points of interconnection with the existing utility grid. Additionally, the already disrupted and cleared land typically can’t be used for more traditional commercial development, as in the case of a capped landfill, or vacant buffer zones such as our project on Vermont’s only active landfill.
Landfill and brownfield owners are increasingly covering their sites with solar panels to generate revenue, defer maintenance costs, and realize energy savings. What’s more, on both a state and national level, environmental departments are actively promoting the development of solar landfills by assessing potential sites, developing educational tools and providing funding. Massachusetts, in particular, has been a leader in embracing landfill solar development, despite the fact that only 7% of landfills are in the Northeast. The majority of landfills are located in the sunniest regions of the country—nearly 40% are located in the West, and 35% are located in the South—and often in states with policies that support solar.
Despite these benefits, not every landfill or brownfield site is easy to build solar projects on. There are several major factors to take into account before solar energy can be considered. Project developers determine whether a site is feasible for solar by assessing site location, site characteristics, and available market incentives.
Proximity to environmentally protected land such as wetlands, marshes, swamps, riverfront areas, flood plains or even land located within a buffer zone (usually within 100 feet of protected land) can handicap a project from day one.
In some states, like Massachusetts, a developer might need to file an Environmental Notification Form if the proposed renewable energy installation has a nameplate capacity of 25 or more megawatts (MW), or if the construction of the solar project will require the alteration of one or more acres of bordering vegetated land. Protected lands can sometimes require permission from conservation commissions that could take up to six months to obtain.
An experienced solar consultant or developer with a good understanding of the usual permitting costs and scheduling setbacks can help ease this part of the process. Moreover, when researching the feasibility of a solar project on your landfill, make sure you have access to a description of all existing utilities, site plans, site assignment limits and abutting properties within a 500-foot radius.
Aside from the need to pull permits and file notices with the local authorities having jurisdiction (AHJ), the closer your property is to a three-phase electric power line (13.8 kV line is common) the better. In some rural areas that are predominantly residential, there might only be a single-phase power line, which will most likely lack the capacity for a large-scale solar installation. One good rule of thumb is to know whether there are any large commercial electricity users in the immediate vicinity, because their circuits are more likely to have the necessary capacity requirements.
Any time you need to trench and run conduit a lengthy distance to reach your point of interconnection (POI) to the grid, the cost of the installation is going to increase. That said, landfill solar projects that have called for an especially long run to the POI have still seen the economics work out. Nevertheless, the closer to the POI, the higher the return on investment.
Landfill Site Characteristics
In order for the installation to stay in place and resist wind loads and other environmental conditions, a certain amount of settling of the fill must first take place. The majority of settling occurs in the first 10 years. If the site is young, there might be some erosion and contiguous settling concerns. Conversely, the site shouldn’t be too old because caps put in place before a certain date (15-20 years) might require a preliminary third-party environmental assessment and updated closure measures that will cost more money up front. Make sure to review your landfill closure/cap design plan at the beginning of the development process.
The ideal landfill site for a solar power installation is one that is relatively flat and has at least five acres of unobstructed land (forest, shading for adjacent buildings, etc.) To avoid any potential sliding of a ballasted array, dome- or bowl-shaped fills will require landscaping to terrace any sloped land, and the solar panels will need to be spaced to avoid shading from adjacent panels. That will add to the upfront costs.
A good understanding of what kind of waste is in the fill or soil is also crucial during the permitting process. If the waste is in any way toxic, additional precautions may need to be taken by the solar photovoltaic panel installers during the construction phase of the project. There’s also the potential that additional permits need to be pulled just to work on the site.
Financial Incentives for Solar Landfills
The economics for solar landfill projects are best in markets that offer incentives. For tax-paying entities, there is a federal investment tax credit that is applicable in addition to state-based incentives. Some states offer upfront cash rebates based on the size of the system to be installed, while others spread rebates out over a five-year period based on the system’s actual energy production. Private landfill/brownfield owners can also recover investments in solar PV through depreciation reductions called the Modified Accelerated Cost Recovery System. Solar PV is specifically eligible for a 6-year accelerated depreciation schedule.
Once your site is deemed feasible for solar, it is necessary to work with city agencies to find out what local permits are required – an important step that will result in well-informed bid documents.
The typical permitting process for landfill solar projects includes obtaining a permit for use of the landfill from an overseeing solid waste state agency, local permits and approvals from various boards and agencies such as the planning board, zoning board, and conservation commission, and an interconnection permit with the local utility.
The reason for such an arduous approval process is to address the most common concern of the regulatory agencies: whether the construction and operation of the solar energy system is going to impact the integrity and functionality of the landfill’s cap.
In order to protect the landfill cap and minimize the risk of penetrating the protective membrane, the solar power installation should be designed to sit on the landfill’s surface. This is known as a ballasted installation and requires no excavation or disturbance of the landfill’s cap or protective membrane.
Through the various design steps, modifications can be made to the system’s racking design in order to best meet any requirements, as well as the overall goal to maximize energy production and savings.
Installing a solar energy system continues to be one of the best options for private and public owners of landfills/brownfields to generate additional revenue and offset costs of maintenance. Whether installed on a capped landfill, on vacant buffer zones of an active landfill, or on a brownfield site, solar can generate huge savings. By consulting a trusted and experienced solar developer, property owners can easily determine if going solar is the right choice for their developmentally challenged sites today.