Many of the emerging questions as we move into a “hydrogen economy” can be summarized: how is it supposed to work? What do we do with hydrogen? Southern California Gas, or SoCalGas, the main natural gas utility for the region, has provided some clarity with its Hydrogen Innovation Experience. Since SoCalGas delivers natural gas, blending green hydrogen with natural gas is one of the main options showcased in the project.
Making all the required mechanical elements of this project work together was one of Emerson’s tasks. We shared responsibility with Brian Burkowsky of Caltrol, an Emerson impact partner and my co-author on the article, along with Spartan Controls, another impact partner. How it all came together is the topic of our article in the July issue of H2 Tech magazine, Optimize Self-Generated Green H2 Consumption Via Fuel Cells and Natural Gas Blending.
The Hydrogen Innovation Experience is a demonstration project, and it is consequently far more involved, elaborate, and expensive than would be practical for a typical single-family residence. It’s more the type of installation that would be for an apartment complex or multiple homes in a neighborhood. As the article describes:
The main photovoltaic array produces 6 kW during peak times, plus supplemental power from panels on the house roof. All power generated by the arrays is channeled to the battery system, which can store a maximum of 300 kWh, and it is distributed from there. The electrolyzer is capable of delivering 1 kg of hydrogen per hour. It consumes most of the power generated by the arrays, so it is only used at peak times.
The home is capable of producing all its electrical needs via the photovoltaic array. It stores power either in the battery or by making hydrogen. How is it possible to use that hydrogen, and what effect does it have on the home’s sustainability?
First, there is a fuel cell capable of turning the stored hydrogen back into electricity when needed. Second, the hydrogen can also be blended with natural gas as a means to reduce the amount of natural gas consumed by the home.
SoCalGas has performed extensive experiments on the practicality of running conventional natural gas appliances (hot water heaters, clothes dryers, kitchen ranges, etc.) at a wide range of hydrogen and natural gas blends, and has concluded that a hydrogen blend as high as 20% can work with unmodified appliances in most cases, while providing a significant reduction in overall carbon intensity. This determination prompted the next challenge: How to mix hydrogen into the natural gas flow on a scale required for this project, with applicability for scale up.
The answer to that question is a major part of the article, and it goes into detail about the blending system that our team put together. It has the ability to handle the wide turn-down range necessary to accommodate characteristic residential natural gas consumption patterns, along with varying blend proportions. It required a creative control strategy, using Emerson’s Micro Motion Coriolis Flow Meters and Fisher Control Valves, plus a Rosemount X-STREAM XEFD Continuous Gas Analyzer to verify the final mix. Give the article a careful read for some useful lessons learned.
The installation has proven highly successful, and it has provided a critical test and evaluation platform for subsequent projects. For more, visit Emerson.com hydrogen blending page. You can also connect and interact with others in the Emerson Exchange 365 community.
