Harness Methane—5-2014

For years I had heard about a mysterious source of power here in La Plata County. This month I had the chance to see it for myself.
Perhaps you have heard the term “San Juan Basin”. It is not a river basin, but rather a geological formation that is rich in oil and gas. Durango sits close to the Basin’s north edge. Shaped like an irregular bowl, communities near its borders also include Cortez, Shiprock, Gallup, Cuba and Pagosa Springs. The edges of the Basin are close to the surface, but it is thousands of feet deep in the middle.
Much of our county’s wealth is thanks to the gas that is found in coal seams in this formation. Fortunately the coal here gives up its natural gas (primarily methane) easily. In other areas and other strata the rock has to be fractured (“fracked”) to produce enough gas to be profitable. That is another, concerning story, but this is a happy one.
The coal seams come to the surface at the edge of the Basin; this is called an “outcrop”. In some places this is pretty obvious—even to me who knows almost nothing about geology. Unfortunately, where the coal daylights there are often appreciable emissions of methane. You cannot smell it, but where it is emitted under water you can see bubbles. If methane collects in a confined space, such as a home built on the outcrop, it can cause an explosion.
Not only is this a fire hazard, but also methane is a greenhouse gas (GHG). Indeed, it has a much stronger effect than CO2, the GHG that gets the most attention. Depending how you measure methane’s effect—long term or short term, by mass or by volume—it is 20 to 70 times as destructive as CO2. The world’s best scientists acknowledge that the climate change that the world is experiencing is due to GHGs, especially CO2 and methane. We should do whatever we can do to decrease methane emissions.
Another problem with methane is that it inhibits the growth of plants where a large quantity escapes to the surface. Indeed, aerial surveys are used to spot methane seeps because you can spot where trees are stressed or dead due to the gas. Often the soil is bare in those areas.
What can be done to limit the escape of methane from the coal bed, and can this gas be put to good use? An experiment was started right here in La Plata County in the early 1990s. With funding from BP and the Colorado Oil and Gas Conservation Commission (COGCC), land was bought where there was a high-output seep. The earth was dug up, perforated pipe laid and covered with sheet plastic, then this was covered with native soil. Pipes lead the gas to a shed where it is used to run a turbine that then turns a generator. The electricity is then fed into a power line. Our electrical coop buys this power, and says that it improves the quality of the service to the neighbors.
It is easy to see the areas where methane was being captured. Healthy green grass grew there, but it was obvious where the methane was not being collected. The ground was bare where the gas still bubbled through the soil.
This system is a win-win proposition: dodgy methane is captured and put to good use. Unfortunately it doesn’t pay for itself yet. It cost $350,000 to establish and it costs more to run than the value of the power it produces. Thanks to BP it is still operating, however.
I am pleased that BP and COGCC chose our county to build this experimental unit. It is the first to use this technology in the world! The unit is win-win-win: it keeps methane out of the atmosphere, it generates electricity and it improves the soil. Its only problem is that it is expensive to run.
Independently, the Southern Ute Tribe is experimenting with a different technology to attain similar goals. They use a series of shallow gas wells close together where a lot of methane is emerging from the outcrop. This has the advantage that the natural gas can be collected and sold along with gas from other wells.
We live in a beautiful, geologically exciting area. Our natural resources are usually blessings, but can also pose problems. Fortunately people with imagination and skill at times can turn liabilities into assets.
© Richard Grossman MD, 2014

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Creative Commons Attribution 3.0 United States
This work is licensed under a Creative Commons Attribution 3.0 United States.