Retired Landfills Become Solar Infills

Dana Blankenhorn
January 13, 2011 | 6 Comments

For years, Atlanta commuters driving up I-675 and then turning west toward Hartsfield Airport were greeted by the sight of an enormous “Mount Trashmore” on their left, DeKalb County's Hickory Ridge landfill.

That mountain having reached its optimum height, Republic Services was stuck with the task of trying to keep it stable and get some use out of it. This week it would have made a great ski hill. In August, maybe a water slide?

Armed with $2 million from the 2009 federal stimulus Republic is turning Hickory Ridge into a “solar park.”

Global Energy Holdings of Atlanta has contracted with Republic to harvest the natural gas seeping out of the mountain. Carlisle Energy Services will install a “Spectro PowerCap” to contain the gas and provide solar power.

Carlisle will first grade the hill, then lay down a 60 millimeter sheet of thermoplastic polyolefin (TPO) over it. It will place Unisolar solar panels on top of the membrane and connect them up. The company estimates the cost of the total system as being no more than a standard landfill closure.

Unisolar systems are not efficient power generators. Prices have been falling quickly. But the TPO membrane keeps gas from seeping out, so it can be taken out in a controlled way, and it keeps dust from blowing around. The solar power is a bonus.

The final system is expected to have a capacity of 1 Megawatt (MW), with the electricity being sold to Georgia Power for the bargain price of 15 cents per kilowatt hour.

Republic engineering manager Tony Walker admitted to the Atlanta Journal-Constitution that Georgia Power doesn't pay much for renewable energy, but the gas is valuable, the closure costs no more than a standard solution, there's $2 million in government money to pay for it, and there's all that publicity to be gained.

The Georgia Solar Energy Association is proud that it recently convinced the Georgia PSC to double the amount of energy Georgia Power buys for its Green Energy Program, by 1.5 MW, at a price of 17 cents per kilowatt hour for smaller projects, and bigger projects like the Republic plan taking a lower price. GaPower hopes to sell 5.4 MW of power under the plan. They're not trying and still doing well.

Would this have happened without the stimulus? Maybe not the solar panels. But maybe so, given the positive spin the garbage company is getting. The only real cost is the panels and connection – everything else makes enormous economic sense.

What lessons do you take from it?

The information and views expressed in this blog post are solely those of the author and not necessarily those of RenewableEnergyWorld.com or the companies that advertise on this Web site and other publications. This blog was posted directly by the author and was not reviewed for accuracy, spelling or grammar.

6 Comments

ANONYMOUS
January 18, 2011

To answer acfan"s 1. I have worked with and instualled Unisolar laminates They thare not Stainless steel. They are flexible. they have some stretch and would conform with the earths settliing... If not fastened too tightly to start with. (right engineer me)
2.They only under perform if you measure onlt square inches (not cubic inches) since they are only .12 thick it take more surface area to get the same amount of energy from them.-- But because they are only.12 thick they start performing almost an hour earlier each day and are still performing an hour longer each evening(because the sun has only one crystal to penitrate also since they are connected molcularly not in series by wires they donot have shadow effects (one shuts down they all shut down).
3. Over heating That's a bunch of crap if it over heats it is because the installer does not know what he is doing. The membrane is .12 thick.
4. Unlike rack type systems if a pucture does happen the enntire system does not shut down. Joe Dell

ANONYMOUS
January 18, 2011

Thomas M
January 14, 2011

There is a similar mount trashmore in my city for which RE was proposed. It was previously capped and piped for methane. The main point for not moving forward was, as mentioned already, is the settling and movement of the site.
Installing rigid systems, or fixed glued systems, obviously would have it's problems. But what about flexible designs? I have yet to see any racking or mounting systems that incorporate such ideas. I hope I am not the only one who can see the benefits of such installations. EASILY anchored and adjusted, free to move and be moved, removed and relocated or stored,....

Dana Blankenhorn
January 13, 2011

ecdfan I don't think $2 m is too much to pay to see a failure here. It's going to be a public one, and that will warn people away from this particular "solution."

This assumes you're right, of course. We'll see.

ECD Fan
January 13, 2011

Ahh, that's the whole point. There's $2 million in TAXPAYER (not government!) money to pay for it, and there's all that publicity to be gained. The project, of course, makes no sense - neither engineering nor economic. Here is why:

1. Gluing stainless steel Unisolar PV laminates to an elastic geomembrane is a recipe for disaster. Geomembranes are designed to stretch and accommodate the ground as it settles in landfill. Stainless steel cannot stretch. As result, over time, the adhesion between the laminates and the membrane will be lost, resulting in flying PV laminates, disconnected wires and possible short-circuits. This will give you an idea what happens after about two years under the Sun:

http://picasaweb.google.com/fan.of.ecd/FloridaInternationalUniversitySolarInDistress
(and the ground there was not moving!)

2. Unisolar laminates are not just inefficient and afflicted by severe long-term performance degradation, they will also underperform relative to regular PV modules on racks due to a) overheating from the lack of ventilation, and b) suboptimal tilt (unlike racks, they have to follow the tilt of the landfill slope).

3. The fact is, there are hundred of megawatts of regular PV installed on landfills and brownfields all over the words, mostly in Germany. Those installations, though subsidized, still make more engineering and economic sense than this project.

4. Republic Services knew all that. In fact, their first experiment, the Tessman Road Landfill proved to be a monumental disaster. That installation was supposed to generate 182,319 kWh a year (see page 25,
http://docs.google.com/fileview?id=0B0DZkzLqH2XLOWJjOGU5MzMtNTBlNi00OTJmLWIxZTMtMmJlMWRiZWY1Yjll&hl=en&authkey=CMqlsssD ) . The installation has generated just 143,377 kWh in the past 12 months. In other words, the system is already underperforming by more than 20%.

The waste disposal operator surely knows how to waste taxpayer money!

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Dana Blankenhorn

Dana Blankenhorn has covered business and technology since 1978. He covered the Houston oil boom of the 1970s, began making his living online in 1985, and launched the Interactive Age Daily, the first daily coverage of e-commerce, in 1994....