The Mars Rover Curiosity has been broadening our knowledge of the Red Planet and, especially since his selfie, seems to have his own personality. Now I think of WALL•E when I think of him (it). But the technology that went into him is also helping us back here on the Blue and Green Planet.
Methane escape is a concern both because of the loss of useable energy and because of its propensity to trap greenhouse gases. Methane can trap between 20 and 30 times more greenhouse gases than an equivalent amount of carbon dioxide. “Natural gas,” the fuel used in many homes for cooking and heating, is made up primarily of methane. Natural gas is also used by an increasing amount of utilities to power their turbines because environmental regulations are making coal too expensive. However, it has not been practical to survey pipelines for methane leaks – until now. A number of technologies are being adapted and developed to detect methane with UAS.
NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California has been working to adapt a methane detector used by the Mars Rover to detect methane loss from natural gas pipelines. This is a lightweight, laser-based technology that is being developed in conjunction with Pacific Gas and Electric Company (PG&E) after California passed a law requiring utilities to minimize natural gas leaks from pipelines. The device can come in a hand-held or UAV mounted format, is accurate to 10 ppb, and can use isotope analysis to track a leak to its source.
Separately, an Australian company called Draco Scientific is developing an alternative UAV-mounted optical sensor to detect methane. Their sensors are advertised to have a sensitivity of better than 1 ppm at less than 2.5 kg. They appear to be as less sensitive but lighter – an important factor for any UAS payload. Since an American study found that energy generation from natural gas is more environmental friendly than coal only if the loss of gas is less than 3.2% (from well to ignition), Dr Maryanne Large, Chief Scientific Officer at the company, is excited about how this technology will aid energy producers.
Draco Scientific is also working in conjunction with Melbourne Water to increase the recovery of biomethane from their treatment plants. For those who don’t know, methane is a natural decomposition product from human (or other) waste. If you’ve ever gone by a capped landfill, the tubes sticking out are to release this gas evolution. Surprisingly, Melbourne Water already saves about $5 million per year through trapping this methane, but Draco Scientic believes it can help them trap 20% more and save an additional $1 million. You can read the Press Release here.
Back in the U.S., UAS are combining with another controversial technology – fracking. I personally believe that fracking has net benefits and is being done safely, but there is significant opposition to the technology. A recent report discusses how drones are being used to limit the release of methane from some of the country’s 500,000 fracking wells – something that could both improve safety and efficiency and improve public perception of both technologies.
As a very brief introduction, fracking is used to release natural gas from underground wells. There is gas in the Marcellus Shale deposits, shown below. Pennsylvania has tapped these deposits to great economic benefit while New York has a moratorium on drilling pending environmental studies. The gas, which is about 90% methane, is trapped in the shale and cannot be reached through normal drilling methods. Instead, the well is drilled and a solution primarily made up of water is injected into the shale to fracture it open – hence the term “fracking.” The natural gas is released and trapped for use. Local residents are concerned both that the gas will leak into and contaminate their drinking water and that the fracturing solution will do the same.
Returning to UAS, the traditional method to search for leaks is evidenced by TransCanada Corp., which used manned-helicopters mounted with lasers. The lasers diffract when they hit methane, so the remaining amount of light that returns to the source is used to determine the amount of methane in the air. Robert Jackson at Duke University is researching mounting this technology on UAS. The biggest problem is their weight, which to date has limited flight time to 30 minutes. This is not enough time to assess a shale “play.” Colorado State University Ventures is developing a competing technology using something called cavity ring down spectroscopy (CRDS) that can also deterime if the methane is from natural gas or oil.
Additionally, small companies are receiving grants from the United States to develop UAS-based methane detecting technology. For example, Physical Sciences Inc. (PSI) has received support from the Department of Energy to survey methane emissions from altitudes up to 80,000 feet. Southwest Sciences, Inc. has received a Small Business Innovation Research grant from the DOE to research a lightweight methane-detecing diode laser that can be mounted on UAS.
I will admit that my background is on the legal and chemistry side of this issue, so the methods used to detect the methane are somewhat outside of my experise. The ASME Hydraulic Fracturing 2015 Conference is coming up in the middle of March and I hope to have at least one follow-up article based on the conference.
Needless to say, UAS could prove to be a great resource in detecting methane for a variety of purposes and is a promising application of UAS.