When eco conscious people look at gas wells, the association may incline to the negative ones. But that may not be the case in the future, not after studies and research could find a feasible way to repurpose the wells.
In Pennsylvania, there used to be a lot of oil and gas wells. Using the abandoned ones, scientists may find a future source of affordable geothermal energy.
Professor of petroleum engineering at Penn State Arash Dahi Taleghani said, “This research shows that with creativity we can convert what could be an environmental threat into clean energy and an economic opportunity in places like Pennsylvania.”
Gas and oil wells in Pennsylvania
Approximately, the state has drilled thousands of oil and gas wells, with many before modern regulations. Some are lost over time in fields, forests, and neighborhoods.
The state now requires owners and operators to plug wells which have stopped producing before leaving them entirely.
Unfortunately, not everything happens by the book. There are wells that weren’t completely plugged, not properly plugged, or damaged. As a result, there can be a methane leak into the atmosphere and groundwater. The federal government recently committed $4.7 billion to plug these wells across the U.S.
There has been a debate regarding actions to make of the abandoned wells. One side wants to seal them completely to prevent leakage of methane and other gases. The other prefers to see them repurposed, benefiting the environment and revenue streams.
Dahi Taleghani said, “One viable solution is for the recovery of low-grade geothermal energy. This has the potential to simultaneously produce a revenue stream, staunch fugitive emissions and maintain workforce engagement.”
How the researchers discovered it
The Penn State scientists discovered that geothermal systems are capable to be utilized for repurposing existing oil and gas wells. This technology has the potential to provide direct heating nearby homes as well as farms and businesses.
Other than that, geothermal industry is ready drastic expansion in the future, and therefore will be a good solution for the state.
Coauthor Derek Elsworth added, “This work is important as it addresses the debate of whether to seal such wells, or whether to take a chance on repurposing the existing well for direct access to the geothermal heat.
“The advantage is that you avoid the high cost of well drilling. That typically amounts to significantly more than 50% of geothermal project costs.”
Now, most geothermal projects occur in areas with active tectonics like the western U.S. These areas contain hot rock that’s closer to the surface, where operatmake use of the heat to build geothermal power plants.
Comes an inopportune challenge in Pennsylvania: oil and gas wells are cooler here, just around 170 to 302 degrees Fahrenheit (76.6-150 C). That makes the wells not suitable for power plants unless advances in low-temperature power generation technologies take place.
However, they could still provide direct heat to nearby buildings.
“We have severe winters, and we can use this heat source for direct heating—for heating hospitals, campuses or schools in small communities. It could even be a greenhouse on a farm that uses this heat to produce vegetables over the winter.”
Providing heat with geothermal energy
Heating using geothermal energy from these abandoned wells involves a process that runs tubing into the wells and circulates water or other fluids continually through the lines. When the fluid is warm enough, the heat can then be transferred to consumers.
To make it economical and feasible, the process or technology needs to have a good distance from the well to the end users.
Temperatures in the wells will remain constant, and the heat could provide a continual base load of energy that could be integrated into existing heating systems. Per the researchers, it could also be a complementary sources of other renewable energy like wind and solar, albeit intermittently.
Optimistic, Dahi Taleghani concluded, “This shows that petroleum engineers, and oil and gas companies can be part of this energy transition toward renewable energy.
“These companies more than ever are looking to include clean energy in their portfolio. This could be something that helps them move in that direction with minimal impact and using existing infrastructure.”
Similar study in Alberta
Penn State scientists weren’t the only one trying to take advantage of inactive, abandoned gas and oil wells.
An experiment done by researchers at the University of Alberta looked at the economic feasibility of heating drinking water for cattle.
Initially, this case study modeled the economic pros and cons of putting disused wells on a large Alberta ranch to good use. To be specific, geothermally heating wintertime water for 2,000 cattle.
It’s unfortunate that the idea didn’t turn out to be fruitful for the rancher. However, like the Penn State research, the project provided some useful information for repurposing the wells.
Similar to Pennsylvania and other parts of the world that are rich in oil and gas, there are more than 450,000 inactive petroleum wells in Alberta. Therefore, it’ll be good to find economically feasible ways to reuse the infrastructure. According to lead researcher Daniel Schiffner, it could ultimately ease the financial burden on taxpayers.
“If industry is unable or unwilling to reclaim a well, ultimately it falls upon the government to do so, so retrofitting presents an opportunity for other uses. We can benefit from turning some of them from a liability into an asset, and at the same time offset carbon emissions,” Schiffner said.
Possible uses of the geothermal energy and costs
Schiffner suggests that this study could help projects in other areas, such as food insecurity in Northern Canada. With geothermal energy from the well, the communities may be able to build a greenhouse and heat it well.
On that note, farmers could also build greenhouses near abandoned wells on land left idle after harvest, providing an additional income source.
“We could have some really interesting regional projects, and at the same time, make a small contribution to addressing the energy crisis,” Schiffner said.
The researchers also estimated geothermal power potential of some of the wells, including costs and revenues within a 25-year range.
With a projection of $865,030 of expenses and just $19,255 of benefits, the researchers determined that a retrofit wouldn’t be economically feasible in this case. An expected reduction in livestock feed costs of just over $1,500 per year was too small to justify significant capital spending.
Despite that, the estimate reveal factors that could make well retrofits more financially practical, including choosing wells that were classified as “suspended” rather than abandoned.
According to the study, using abandoned wells could cost up to $50,000 more, due to the extra time and materials needed to unseal it.
Per the Alberta scientists, the estimates of the well retrofit costs and thermal power have two key factors: location and vertical depth.
” Out of hundreds of thousands of wells, this helps quickly find and initially evaluate target areas that could be of interest,” the lead researcher said.
Similar to the finding by the Penn State scientists, it’ll be more economical if the well is closer to its intended use. The farther it is to transport the hot liquid, the cooler and less effective it’s going to get, and in turn the more to spend.
Will there be more geothermal energy in the future?
The Alberta study also suggests that the long lifespan of a geothermal energy source tends to outweigh the initial cost of retrofitting a well. So, other than being more friendly to the environment, the economics could be more attractive to private industry.
Schiffner ended, “That might be an incentive that lets the government transfer the responsibility for some of these orphaned wells.”
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