Enchanted Rock Undertakes Study of Hydrogen Blending
Hydrogen blending offers a way for natural gas generators to lower carbon dioxide emissions, but there is a problem. It also increases nitrogen oxide (NOx). What can be done about this?
That’s one of the questions that Texas-based Enchanted Rock hopes to answer with the University of California Riverside through a recently awarded $2.1 million research grant from the California Energy Commission.
Those watching Enchanted Rock know it’s also using renewable natural gas (RNG) to reduce carbon emissions from its natural gas-fired generators. But it does not use RNG as a fuel; instead, the approach is contractual. The RNG is injected upstream in natural gas lines as an offset.
Hydrogen, in contrast, would directly fuel generators, a process that creates some challenges, according to Ian Blakely, the company’s chief strategy officer.
“One of the challenges with hydrogen is it burns hotter than natural gas,” he said in a recent interview. “So when you combust hydrogen, you end up with potentially higher local emissions and specifically NOx emissions which can cause respiratory issues. So this grant is looking at: How do you blend higher and higher hydrogen while controlling NOx to acceptable levels?”
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Enchanted Rock is making two key modifications to its core generators to burn higher hydrogen blends. First, it is adding an exhaust gas recirculation system, which lowers combustion temperatures in an engine. Second, it is looking at various catalysts and secondary emissions controls.
The company hopes its generator technology will be ready to incorporate hydrogen as supply ramps up under new US government incentives.
“What we’re really trying to ensure here is that the combustion side of the technology — being able to use the hydrogen — isn’t the limiter on the rollout of hydrogen, “ Blakely said.
Why not use all hydrogen in the generators?
Blakely said that, at some point, the hydrogen limits the engine’s output, increasing costs. “As you start adding more and more — and this is part of the testing that we’re going to do — you potentially have to start to derate the engine.”
The blending creates a linear reduction in carbon. So a 40% infusion of hydrogen means a 40% reduction in carbon, although Enchanted Rock is exploring ways to improve that ratio.
“Every percentage you can improve on your carbon output is meaningful. We don’t want to wait for perfect to be able to make meaningful positive progress today,” Blakely said.
Enchanted Rock expects the study to be completed next year.