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Oil and gas extraction in places like Texas’ Permian Basin leads to several waste products, including significant amounts of wastewater and flares firing into the sky. Texas Engineer Vaibhav Bahadur is researching how those byproducts, which are harmful to the environment, could be repurposed to serve as key elements in the creation of “green” hydrogen.

Bahadur, an associate professor in the Walker Department of Mechanical Engineering, recently published a new paper in the journal Desalination about a new way to potentially produce green hydrogen. It involves using the energy wasted via gas flaring to power reverse osmosis, a common, low-energy technique used for municipal water treatment. Hydrogen production requires pristine water, and this process satisfies that need by removing salts and other elements from the equation.

Learn more about green hydrogen in the Q&A with Bahadur below, as well as his research, next steps and its broader implications.

You’ve just published some new research about reusing wastewater in oil production to help generate hydrogen. Tell us more about that.

Vaibhav Bahadur: This is about a problem that touches three areas: energy production, water management and environment protection. At the heart of it is green hydrogen, which is generated by splitting water – removing the “H” from H20 -- using energy from renewables. While we have abundant wind and solar in many parts of the planet, including in Texas, what those places often lack is the clean water needed to produce green hydrogen. Texas and other oil-producing areas have plenty of water as a byproduct of energy production; however, this water is packed with dissolved salts, and it costs a fortune to transport and dispose of it.

Bahadur Vaibhav

It makes sense to treat this wastewater and  use the treated, pure water to produce green hydrogen locally. Importantly, the energy needed to treat wastewater can be provided by onsite excess natural gas, which is typically flared. This is what our research is about; it uses two waste streams to create a valuable commodity (clean water) while also solving pressing environmental issues.

Why is green hydrogen important?

VB: Hydrogen will play an important role in our future energy mix for several reasons.

  1. It allows us to store wind and solar energy, which can then be used as needed without any emissions.
  2. Hydrogen allows us to leverage existing gas-related infrastructure like pipelines, which has huge economic ramifications.
  3. Hydrogen is likely the only viable option for decarbonizing many heavy industries and heavy-duty transport because of the higher energy density compared to current electric vehicle batteries.

Clearly, hydrogen is going to be very important in the future. In that context, sustainable hydrogen production is critical. Today, 95% of hydrogen is produced from steam reforming of natural gas, per the U.S. Department of Energy.

What are the barriers to producing green hydrogen today, and how does your work overcome those?

VB: Most experts will say that the biggest barriers for green hydrogen are the high costs of renewables and their intermittent nature. While that is no doubt true, another barrier comes from the fact that green hydrogen production is water intensive. A single kilogram of green hydrogen can need up to 12 gallons of water withdrawals.

In addition to the quantity, the quality of water is also very important. Water going into the electrolyzer (for splitting) needs to be stripped of all dissolved salts, gases etc. So, this is of higher quality than demineralized water. In contrast, water from oilfields is hypersaline with salt levels much higher than those in seawater.

In our research, we analyze the use of reverse osmosis to convert hypersaline water to high-purity water. Reverse osmosis is a low-energy consuming, membrane-based technique that is associated with municipal and seawater treatment. We show through modeling that it can be used to treat meaningful amounts of oil and gas-produced water to produce green hydrogen-grade water.

What is the next step for you in this research?

VB: This work has attracted much attention, and I am very excited about its prospects. In particular, we are focusing on the Permian Basin in Texas. While the Permian is associated with oil and gas production, which creates plenty of wastewater, it has enormous green hydrogen potential due to abundant solar and wind resources. To make this work, we need lots of fresh water, which we don’t have in the Permian. We are now focused on developing Permian-specific water treatment solutions to use the wastewater flowing out of Permian oil and gas wells . Permian has some of the most brackish water on the planet, and we are looking at advanced water treatment techniques. If we can succeed in the Permian, we can succeed anywhere!

What are the implications of this research in the context of climate change and sustainability?

VB: While we want our energy to be 100% carbon-free right now, the reality is that we will likely have a gradual transition from hydrocarbons to renewables over the next few decades. Oil and gas will continue to meaningfully contribute to the global energy mix, and it is vital to minimize its environmental footprint.

This is what is so fascinating about this research. We are using waste products from oil and gas production, which harm the environment, to develop greener energy solutions for the planet. In particular, we are helping numerous oil and gas producing states and communities participate in this  energy transition, and not lose out because of it. This is a win-win situation for everyone in many aspects.

Beyond this particular study, our work has global ramifications. Green hydrogen is a buzzword around the world, and large quantities of high-purity water will be needed to make this happen. Tap water is simply not good enough. Our work highlights the importance of considering water treatment and water management when planning for hydrogen projects. Not every place on the planet will have wastewater from oil and gas fields, but our solutions can work equally well for seawater and groundwater as well.