It’s been interesting watching the evolution of our collective responses to climate change. Just a few years ago, we were all happy to see natural gas replace coal for power generation, eliminating a huge source of carbon dioxide. Eventually we realized that while natural gas is a much cleaner burning fuel than coal, it is still a fossil fuel and produces carbon dioxide, just less of it. Hydrogen is the next phase in the strategy, but how we make it and what we do with it can have major effects on climate.
One approach is blending it with natural gas to reduce carbon content. While this process makes sense, there can be cost and operational complications. Minimizing the downsides and making this approach work are the topics of my article in H2 Tech, Blending Natural Gas and Hydrogen, now available online.
The first consideration is the way hydrogen is manufactured since it does not occur naturally.
H2 is mostly created using industrial processes that can also produce significant GHG emissions. Green H2 can be created through electrolysis powered by sustainable sources such as wind or solar, emitting no GHGs, although supplies remain expensive and in short supply. An alternative option is to use existing industrial processes such as steam methane reforming (SMR) or autothermal reforming (ATR) to make H2 and capture and sequester the emitted CO2. This blue H2 produces significantly fewer GHG emissions and is more readily available in the short term since it utilizes existing industrial processes as a starting point.
The article explains why concentrations of hydrogen in natural gas should not exceed 20% or 25% in most areas for regulatory and practical reasons. That leaves companies wanting to use this option in a position where they must work with the local pipeline company or utility to monitor how much hydrogen is being added to the natural gas flow.
A typical H2 blending station includes a full-bore ultrasonic flowmeter to measure the incoming gas flow, a Coriolis meter and control valve to measure and control the H2 addition, and a downstream gas chromatograph to confirm the resulting blend.
The article goes into more detail on how these products interact, and Emerson provides all four of the technologies mentioned:
- Micro Motion™ ELITE™ Per Performance Coriolis Flow and Density Meter Peak Performance
Based on the available research, it is likely that H2 blending will be employed as clean H2 sources become available and price competitive. If specified correctly, existing instrumentation and controls are available for these applications, and ongoing research may yield improved options.
For more information, visit Emerson’s Renewable Fuels pages at Emerson.com. You can also connect and interact with other engineers in the Sustainable Energy and Chemical Processing Groups at the Emerson Exchange 365 community.
