An article from
Pollution Equipment News
Into their fifth year, little solar piston pumps
dewater, remediate – and the power is free
The concept of solar pumping is not quite new anymore for water wells, and operators in other industries, such as toxic remediation and solid-waste management, have given solar piston pumps a try, with initially good results.
Conceptually, there is a lot to like about low-cost, lightweight, portable, adaptable piston pumps that pump virtually any fluid without the bother and expense of electric or pneumatic power.
No greenhouse-gas emissions, no air vented back into the well, no below-surface air or electricity, no problem running dry, little maintenance, any angle to horizontal – the list is strong
But do they work? Do they last? Are solars practical outside the Sun Belt?
A Problem in Iowa
The Cedar Rapids/Linn County Solid Waste Agency, which serves Iowa’s second largest county, installed gas-collection systems in 2010 for both active and closed landfill cells as an expected revenue generator. Methane production, however, came up short of the results predicted by modeling.
In 2011, close monitoring determined that high levels of liquid from one of the Agency’s landfills was filling the wells and negatively impacting gas production. In addition, the Agency suspected that leachate might be migrating slowly toward groundwater.
The Agency contacted regional engineers with The Foth Companies to investigate as well as offer and implement solutions. The firm prepared a preliminary assessment and controlled-measures study in October 2011 to gather data for planning and implementing corrective measures.
Foth engineers postulated that lower liquid levels in the collection wells would improve the efficiency of the gas system and, secondarily, reduce potential groundwater impacts. The study suggested the use of low-flow pumps to reduce levels. Lead engineer Brian Harthun further suggested testing the viability of pumping with solar power for efficiency and cost savings.
One Tough Test
Foth initiated the test in December 2011. Four months in the dead of winter -- at 42º North latitude (roughly equivalent to Toronto), with 65 to 76 percent cloudy days and only 10 to 11 hours of sunlight a day -- proved a rough challenge.
Linear-rod reciprocating-piston drive motors employed by the engineers were identical, but each used a different power source: 1) In the first well, direct electric power was converted from 220-volt AC to 24-volt DC, 2) in well #2, direct power came from 12-volt DC batteries charged through a mounted solar panel, and 3) in the third well, the motor was driven simply by a solar panel with no backup assistance.
The pumping flow rates were between 1 and 2 gallons (3.78 to 7.57 liters) per minute. Pump intakes were set 1 to 3 feet above well bottom to avoid accumulated silt or debris. Liquid levels were measured periodically through March 2012, and pressure transducers were installed March 6, 2012 to measure liquid elevations every 15 minutes. Percentages of methane and oxygen were measured periodically before and during pump operations.
Results: Migration Remedied; Up to 20% More Gas
By early April 2012, the results were in. The analyses showed that the low-flow pumps – from Blackhawk Technology Company -- reduced average 24-hour liquid levels sufficiently to remedy the migration issue, and that those lower levels were consistently maintained by all power options, including solar only. Although overnight liquid levels increased somewhat at the solar-alone well, they dropped again in the morning when the pump “woke up.”
At the same time, the lower liquid levels from all three power options exposed an additional 15-18 feet of screen in each well -- between 75 and 90 percent more — which resulted in additional gas flows of 15 to 20 percent. “We were quite pleased both with the operational and financial performance of the solar pump,” said Harthun, the lead engineer. He cited steady, uninterrupted performance and lower costs of installing and maintenance. He said that eliminating the need to run electric or pneumatic lines to the closed cell was a major attraction.
Update to 2016
That was then. What about now? Harthun is still pleased. The Agency installed several more solar piston pumps in 2012 after the successful tests, and the pumps are operating at levels consistent with the early results. On-site management also is pleased with low maintenance requirements and low incidences of repair.
Is a solar pump right for your application? If you have well depths beyond 400 feet or need flows greater than 2.7 gallons per minute, then probably not. There is a latitude limit as well. Batteries, which can be expensive and usually must be purchased separately, are required for continuous, 24-hour operation. A bit of insulation might be needed in the coldest months. And, of course, there must be no obstruction between the panel and the southern sky.
But with decided advantages, including low cost, durability and free power, solar piston pumps are worth a strong look.
Blackhawk Technology Company provides advanced-technology piston-pumping solutions for a broad range of well- and sump-based applications, including landfill leachate, gas-well dewatering, condensate-recovery sump, groundwater remediation of chemicals, hydrocarbons and gas, and shallow oil recovery, Blackhawk is the originator and No. 1 manufacturer of pneumatic, electric and solar powered positive-displacement piston pumps with motors above the wellhead — next-generation technology refined by 25 years of ongoing, customer-driven improvements. Blackhawk systems of rugged pumps, downhole components and controls are economical and simple to operate, emit no greenhouse gases, are unaffected by differential pressures, resist bio-fouling and abrasion, and are low maintenance and safer for workers. No company offers more real-world piston-pumping experience in remediation sites, landfills and recovery sites throughout North and South America, Europe, Asia, Africa and Australia.