Getting More Gas

Optimizing gas collection at landfills is the core component of Loci Controls’ new technology.
By Anna Simet | July 24, 2015

When a landfill owner who had recently installed a landfill gas-to-energy system was not getting the volume of gas he initially expected, he asked MIT graduate student Melinda Sims to help him solve the problem. After hatching the idea of automated wellheads in 2012, Sims and fellow graduate student Andy Campanella found themselves launching a startup company, that, in just a few years, has been able to prototype, raise adequate seed money, hire on engineers and additional staff and complete two pilot installations. The future looks bright for Loci Controls, which believes that its technology appeals to not only those collecting and utilizing the gas for a variety of purposes, but landfill owners, as well.

Sean Bamforth, director of business development, explains that the continuous monitoring WellWatcher device is mounted onto the gas-collection wellhead, and monitors collected gas for temperature, flow rate, and pressure, as well as methane content, carbon dioxide content and oxygen content, all parameters typical for landfill gas measurement devices on the market today. What differentiates the device, however, is that the automatic control WellWatcher has a remotely actuated valve along with those measurement capabilities. “The valves control the extraction pressure on an individual well,” Bamforth explains. “The idea is to adjust extraction pressure to maximize the energy content of the gas being produced from the well. We use distributed feedback loops from the WellWatchers, and are able to make frequent changes to the collection system to match the landfill-gas collection rate with the rate at which it is being produced.”

This allows a gas collector to increase collection efficiency and get more gas by taking more frequent readings and making adjustments.
 
How It Works
Under current practices, a landfill technician uses a handheld meter to test every well on-site once or twice a month. Reasons for testing include ensuring a negative pressure in each well, making sure oxygen doesn’t go above a certain percent—typically 4 or 5 percent—and that the temperature isn’t over a certain threshold. Elevated temperatures can indicate a fire, and higher oxygen is undesired, as it fuels the fire and can stifle methane generation.

 Typically, a technician analyzes data and makes changes to, or “tunes” the well field, in hopes of increasing output.  “However, wells are highly correlated and whenever a change is made to one well, the entire system changes,” Bamforth says. “When you suck harder from an individual well, more methane isn’t being generated—it’s the same volume of gas produced, which is the function of environmental conditions, the waste in landfill, how much moisture and water are in the landfills, lots of things we have no control over—but rather, the goal is to try to exactly match the collection rate with generation rate.”

 If a technician measures one well and makes a change, and then measures another and makes a change, the latter change could undo the previous change. “So when a technician pulls harder on one well, it changes the dynamic of the entire landfill, and it might be a detriment to other wells,” Bamforth says.

With Loci Controls’ technology, a series of changes can be made and evaluated in real time. “We can continue doing that until we find an optimized state that a technician might happen upon, but would be impossible with only one or two meters going at the same time,” Bamsforth says. He compares the automated system as possessing the same capabilities as 20 technicians on-site, taking readings every hour and communicating with each other to maximize output. “We do this by running the measurements taken on site through a custom control algorithm that is designed to maximize energy output,” he says.

While meters, or handheld valves, aren’t placed on all of the wells—it is currently cost-prohibitive—Loci takes advantage of a phenomenon commonly seen in landfills: the 80-20 rule. “That means 80 percent of the gas comes from 20 percent of the wells,” Bamforth says. “Wells collapse over time, get flooded out and aren’t as effective, so a certain small percentage produce the majority of the gas, and those are the wells we want to be on.”

The company’s first installation was at the Crapo Hill Landfill in Dartmouth, Massachusetts, which was funded by a grant from the Massachusetts Clean Energy Center.

More Gas, More Power
Crapo’s landfill gas-to-energy system is equipped with four 0.8-MW gensets, but the landfill operators were only getting enough gas to run three of them. “Essentially, they had a multimillion dollar engine going unused,” Bamforth says. “We installed, and they were able to turn on the fourth engine because of the additional gas we were able to get them.”

Gas production at Crapo was increased by 25 percent, resulting in a 10 percent increase in electricity sales. Bamsforth notes that the gas is 50 percent methane, so although gas flow went up 25 percent, the energy content only rose 12.5 percent. “Due to some efficiency losses in the engines, the result was a 10 percent increase in power production, but that was significant for them. With all four running at 80 percent capacity, they’re a little less efficient—at full capacity is where they’re the most efficient. It could have been as been as much as a 14 percent increase in additional electricity sales, it just so happens we got the short end of the stick with the efficiency curve.”

Most power plants are oversized and have excess capacity, and Bamforth says the technology will help them utilize that capacity, increasing revenues and lessening payback time on equipment.
In addition, at Crapo, the system cut fugitive gases by 25 percent. “That’s what causes odors—and odor complaints, Bamforth says. “It’s something landfill owners care about, so even if with unused capacity it can still be a benefit. Because we’re checking every hour versus once a month, we can find out if there is one or more flooded wells right away. They can send a worker to pump out plugged wells so they can produce gas again. If three wells are plugged and it goes on for three weeks, you’ll get some local emissions in that area, whereas if you identify that issue immediately, you can avoid it. The No. 1 reason landfills are shut down early is because citizens band together because they’re annoyed with the odors.”

A second installation at Pine Tree Landfill in Maine was recently completed, and other sites are interested in trying out the technology, but haven’t yet signed up, according to Bamforth. “We recently revised our pricing to basically breakeven to help incentivize people to use our service,” he says. “Our biggest challenge right now is getting people to be an early adaptor of our technology.”

Bamforth says he is unaware of any others in the world with a technology exactly like Loci Controls.’  “There are companies that make monitoring devices that can measure all the same things we can, but they are either handheld and must be charged on a daily basis, or they must be hardwired into the electrical system. Our units are fully wireless, they work off a battery, and are charged via solar. Each unit also has its own cellular modem, and these last two points are really what differentiates our product.”

The technology might also appeal to high-Btu projects—in particular, the monitoring component. “For them, there’s a very high cost to remove nitrogen, for example,” Bamforth says. “They’re more excited about using the monitoring unit to discover where the better gas is coming from—the purer gas with less ambient air and less nitrogen. For them, it’s more of a quality thing. Our current algorithm, which we designed at Crapo, is designed to maximize energy, which is a function of methane content and gas flow rate. There’s a peak we’re trying to find for the entire landfill. The problem is, particularly for nitrogen, you can’t measure with an optical sensor like you can carbon dioxide, methane or oxygen, and it’s very expensive to take those readings.”

Bamforth adds that Loci Controls’ units won’t possess those capabilities in the near future, but that the company has no reason to believe it won’t be able to provide a solution for people looking for better gas quality. “The information, the data, there’s been no way to get that, and we’ve built a tool that can.”


Authors: Anna Simet
Managing Editor, Biomass Magazine
asimet@bbiinternational.com
701-738-4961