Summary:

Town managers and landfill directors are starting to catch on that their least desirable land might be the perfect candidate for a commercial scale solar energy system. The overlooked potential of “landfill solar.”

landfill

When solar first began catching on, many residents and business-owners began realizing that their rooftops were an untapped asset. A similar transformation is occurring with solar development in “brownfields,” or property in the presence, or potential presence, of a hazardous substance (most commonly town landfills). Town managers and landfill directors are starting to catch on that their least desirable land might be the perfect candidate for a commercial scale solar energy system.

The EPA and the DOE’s National Renewable Energy Laboratory (NREL) announced last year they were evaluating Superfund sites, brownfields, and former landfill or mining sites for renewable energy production. It comes at a time when the solar industry is in debate over which areas for solar offer the best rate of return for projects.

The Southwestern desert has strong sunlight and ample land, but grid interconnection has become a complicated issue and environmental development issues remain. Rooftop installations, on the other hand, often suffer from shading, foliage, pollution, limited space, building structure limitations and other complications.

Why Landfills?

Landfills are, generally speaking, locations close to good infrastructure, properly zoned, flat and wide-open, and in perhaps the greatest benefit, under little commercial development demand.

The potential for mid-sized, distributed generation projects built on landfills is substantial. In our experience, the average landfill has at least five acres and often up to 80 acres of land suitable for solar, meaning there’s a potential 1-16 megawatts (MW) on each landfill. There is roughly 100,000 sites (either decommissioned or operational) across the country, so by installing solar power arrays on just one quarter of those landfills, we could produce a potential 212 gigawatts (GW) of clean energy—almost 500 times the solar energy produced in the U.S. in 2009 (425 MW).

However, not every site is perfect or even suitable for solar. When project developers or financiers are determining if a site is suitable for development, they must consider location, landfill history, land specs and financial incentives.

Location, Location, Location

As most solar pros know by now, proximity to the grid is often paramount for projects to work fiscally. Cost of installations can skyrocket if you need to trench and run conduit lines, particularly if that runs through other individuals’ properties. As mentioned, most landfills are advantageous because they are close to the grid, though that is not always the case.

Project developers should check whether the property is in close proximity to a three-phase electric power line. In rural areas that are mostly residential, for example, the power lines might be smaller and unfit for a larger solar installation. It’s ideal if there are some commercial electricity users in the area already using larger electric lines.

The potential time constraints associated with interconnection are also worth analyzing. Interconnection approval from the utility can be the longest part of the permitting process, taking six to eight months on average for projects over 500kW.

One way to potentially speed up the process is to engage a distributed generation (DG) consulting firm during the process. Many DG consultants are utility ex-patriots who know what questions to ask and when to exert pressure. With their help, a project developer can design their interconnection in a way that will make sense to the utility permitting officers and make it easier to approve.

Furthermore, a property that is near environmentally protected lands –wetlands, marshes etc–can be potentially handicapped by development restrictions. It’s important to know if there is any endangered species (plant or animal) residing on the site. In MA, two projects were recently put on hold because of the presence of the grasshopper sparrow. These cases are rare, but should be taken seriously before undertaking a project.

Even without a rare species, some protected lands can require permission from multiple conservation commissions, which often take up to six months to obtain. In states  like MA, a developer might need to file an Environmental Notification Form depending on whether the proposed installation will generate 25 or more megawatt hours of electricity, or if construction will include altering one or more acres of nearby land.

In addition, timing can be everything. Landfills employ a capping system to cover the waste stored, and the amount of time since those caps were installed can make a big difference. If the site is new (say less than five years), there could still be some erosion concerns. Landfills typically experience the majority of their settling within the first ten years. It is important for the solar designer to understand how much future settling is expected so a racking system can be designed to accommodate this movement. Alternatively, if the capping is old (15-20 years) there could be requirements for a third-party environmental assessment

Site Specs

For a site to be financially feasible, you need a large, flat area that could host at least a 1-MW array. Landfills have the advantage that they often have ample space that could accommodate much more than 1 MW of solar development, but be sure to verify the size when evaluating the land.

As with a typical ground-mount solar installation (ground-mounts are the most common system used for landfills), you should have approximately five acres of flat space available which will generate one MW of energy. For a ballasted array, sloped land will need to be landscaped ahead of time to avoid sliding. Terraced or spaced arrays can be used to avoid shading issues.

Also, keep in mind, we’re still talking about landfills – it’s important to know what sort of waste is kept in these locations. If the waste is toxic, extra time and precautions will be needed for the installers during the construction. Most concerning, however, is that many toxic sites require a permit every time site maintenance needs to be done. While this isn’t usually the case, it can require serious time and resources on a project, particularly if it isn’t planned for.

Money Talks

Not specific to landfills, but still important, are the state and federal incentives available. The federal government renewed the Treasury Grant program, offering 30 percent of system costs paid back in a cash grant. Also, a market has developed to trade solar renewable energy credits (SRECs) as states continue to adopt and expand Renewable Portfolio Standards.

For municipal leaders, state and federal governments, environmentalists and solar professionals, it’s rare to find across the board consensus, yet landfill solar has the potential to please all parties. It’s an exciting trend that we see strong growth opportunities for in 2011.

Joseph Harrison is a project developer at Borrego Solar. He is based out of Borrego Solar’s regional headquarters in Lowell, Massachusetts. He graduated from the University of Massachusetts with a bachelor’s degree in business management.

Borrego Solar has been involved closely with developing solar on brownfields for the past few years. The company has about 3.5 MW of landfill solar under contract in Massachusetts.

Image courtesy of D’Arcy Norman.

By Joseph Harrison, Borrego Solar

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