A Healthy Well Field is Critical for LFGTE Success
by QED staff
Building and managing a high-BTU landfill gas to energy system can present many challenges, but it’s not as complicated as it might seem. The key: start with a healthy, consistently productive wellfield.
Morrow Renewables, formerly South Tex Renewables, specializes in doing just that. Headquartered in Midland, Texas, they began in the natural gas industry before building a reputation as one of the leaders in high-BTU landfill gas treatment. More than 12 years of experience in the LFG field encompasses all aspects, from collecting, compressing and treatment to marketing and even NSPS compliance issues.
For reasons of safety, efficiency and cost control, Morrow Renewables operates all the high-BTU LFG plants the company installs. Producing pipeline quality gas from LFG is a highly specialized process, requiring a trained chemical process engineer who has specific experience with the chemicals present in landfills.
Luke Morrow, principal at the firm, says, “Most projects depend on a well-run operation in order to be successful. Thus, our success is based on experience in operations, robust facility engineering and personnel dedicated to high and consistent run time.
“We are in the wellfield day in and day out, constantly tuning the field, checking for air/gas leaks and maintaining the wellfield equipment (wellheads, piping, hoses, headers etc.). We use a gas chromatograph (GC) to tune each well. GCs are extremely accurate, robust and dependable, unlike other devices landfills might use. Most landfills without LFGTE will only tune their field once a month, which can cause drastic swings in the gas wells and the health of the wellfield.”
Asked to describe the characteristics of a healthy wellfield, Morrow replies, “I can start by telling you what an unhealthy wellfield is. There is a fallacy in this business that the harder you pull on a well, the better you do for compliance. We have taken over several wellfields where there was a significant amount of air coming through the system. A lot of that can be due to bad wells or broken hoses, or some wells that are being pulled so hard that it’s sucking in from the atmosphere, which is actually a fire hazard and is against NSPS rules.
“A healthy wellfield is one where all the air leaks are fixed, and there is a good grade with all the water flowing into sumps without slugging, so you have steady vacuum. In a healthy wellfield you don’t pull in much air through the well bore or the landfill itself, and you have good cover on the landfill so there are no places where air or gas can leak through the sides. You can’t choose the gas the landfill makes, but you do get to choose what other stuff you pull in.”
Morrow Renewables has replaced all the existing wellheads with QED Quick-Change™ Orifice Plate Wellheads (U.S. Patent Number 8,800,597 & patents pending) in their LFGTE wellfields. This has enabled them to achieve more accurate flow measurements and precise adjustment control, essential for tuning wells effectively. Luke Morrow says, “The big benefit is eliminating fluctuations in the flow. The wellheads are built tight, they don’t have air leaks and they are easy to maintain and operate. The graduations on the valve are very helpful and the ease of changing orifice plates is valuable. What we are seeing is maintenance-related savings.
“We cross-train all our field guys and the QED wellheads give us consistency, not just across one wellfield and landfill, but from plant to plant. If they tune a well and come back a week later, they can trust that the well is still going to be right there, as opposed to our old wellheads, where they could set a well at 10 inches of vacuum and come back later and it’s at 15 inches – that didn’t allow us any consistency or trustworthiness in the field at all.
“Data is crucial to us. We want all of our guys reporting data they get from these wellheads, so that a regional manager could look over the readings and know that they made the right decision when tuning. That shows us where the good flowing wells are, and shows us where we do or don’t need to add a well.”
The end results offer significant benefits to landfill owners. According to Morrow, LFG to pipeline systems provide the ability to sell all the gas all the time, unlike electricity generation, where demand for gas varies tremendously between peak and off-peak periods. Similar constraints often exist for low or medium BTU operations where the LFG is delivered to one end user for boiler operation or manufacturing processes; the gas producer is then at the mercy of the customer’s ability to use the gas on a 24/7 basis.
The almost limitless capacity of LFG to pipeline allows the creation and operation of a very healthy wellfield with maximum consistency of gas composition and flow. Together with the right equipment, experienced personnel in the field and proactive well installation, this enables landfills to meet or exceed NSPS compliance regulations.