Planning a Green Hydrogen Microgrid to Ditch Diesel

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When we think of microgrids, we typically think of solar power, wind power, and battery energy storage systems. But there are all kinds of microgrid configurations and an ever growing variety of innovative technologies available to power and benefit from them. For example, in Austria, there’s a microgrid testbed that is used by researchers to examine new concepts and control strategies. This includes research into green hydrogen, an emerging new clean energy storage mechanism that has the possibility to impact a number of industries. Let’s take a closer look at their research.

Green hydrogen is produced by splitting water into pure hydrogen and oxygen using renewable energy. It also only emits water when it is burned. Additionally, hydrogen can be stored in tanks as either a low temperature liquid, pressurized gas, or hydride-based solid, meaning it can be transported and dispensed into vehicles more like traditional gasoline. However, in order to reach mass market penetration, green hydrogen fuel still needs to compete with both traditional fuel sources and non-green hydrogen.

The researchers involved in this project, including Austria’s BEST (Bioenergy and Sustainable Technologies) and Michael Stadler of Xendee, note that others have delved into the integration of hydrogen storage and hydrogen vehicles in smart grids. Others have researched the profitability of green hydrogen produced with solar PV, and yet others have researched centralized hydrogen production. In this project, the researchers’ aim was to take base understandings from those studies and explore a microgrid that integrated green hydrogen production, on-site storage, and usage in vehicles. Yes, as many will point out, battery electric vehicles are clearly winning the real-world competition in passenger transport, with 11% of new car sales in Europe already being fully battery electric, and 19% having a plug. However, long-haul trucking and maritime shipping may eventually make use of hydrogen on a large scale.

For the microgrid testbed itself, the project team identified the ideal technologies as solar PV power systems, wind power systems, hydrogen electrolyzers, and hydrogen energy storage systems. Furthermore, hydrogen fuel cell vehicles would come in and out of the microgrid ecosystem to purchase fuel.

According to the report, “the project team utilized a multi-objective framework which considers CO2 minimization capabilities along with the cost limitations. The optimization framework also uses one year time series data because the adequate modeling of the optimization techniques require a full year time horizon at least for incorporating the renewable energy sources and seasonality of the hydrogen storage in microgrids.”

In other words, this is a full-year study that examines how the microgrid and its various components perform throughout all seasons.

But remember, the aim of this work is not just to examine how the system works, but to create an effective framework for optimizing the planning of a microgrid, and in particular a microgrid that incorporates the various stages of hydrogen production and usage. Additionally, the design  had to be compared to traditional fuel sources as well as hydrogen developed by buying power directly from the utility. The authors cover that further in the following explanation:

“The optimization is performed relative to two different reference cases i.e. the diesel basecase and the utility basecase. In the diesel basecase, the mobility demand of the entire fleet is considered to be covered by the diesel fuel. In the utility basecase, the hydrogen fuel is produced through electrolysis, stored and used to satisfy the mobility demand of the entire fleet using only the utility electricity. After setting up the reference cases, the investment optimization is performed by minimizing the CO2 emissions and keeping a limit on the energy costs that vary in different scenarios. The results include (1) the optimal sizing and dispatch of the technologies, (2) the economical viability, (3) the environmental impact, (4) a comparison between the optimal hydrogen fuel costs and the current market costs of the diesel fuel to identify the H2-Diesel cost gap and (5) the calculation of the carbon prices to close the H2-Diesel cost gap. The uniqueness of this research work stems from contributions toward the decarbonized energy transition in the mobility sector by addressing the five highly important points mentioned above in a single study.”

Interestingly, the diesel base case actually performs better than the utility base case in both annual energy costs and emissions. This is because of the added efficiency of the onsite diesel production which does not suffer from the transmission and generation losses incurred by the utility. Additionally, hydrogen vehicles and systems are inherently quite inefficient, so hydrogen should be created using on-site power sources to minimize losses as well as hydrogen storage and transportation fees. “The utility basecase has 65% higher total annual energy costs and 17% higher total annual carbon dioxide emissions as compared to the diesel basecase. Therefore, the diesel basecase is much cheaper and generates less CO2 emissions than that of the utility electricity-based hydrogen.”

The researchers highlight that although diesel engines beat the utility base case, the biggest win comes from a renewable energy powered hydrogen microgrid. Additionally, this calculation becomes even more favorable when considering increases in hydrogen efficiency, carbon taxes, and tax incentive programs which can make the technology even more attractive. “The most interesting outcome in the utility basecase is that at no further costs, the renewable energy based sources and the hydrogen seasonal storage in the microgrid can provide CO2 savings of around 94%. At 20% reduced costs, the microgrid still constitutes a large share of renewable energy that provides significant CO2 savings of around 74%. Thus, renewable energy based microgrids are highly desirable as compared to the utility based hydrogen energy systems for the decarbonization of the mobility sector.”

In other words, if you’re gonna go hydrogen, go green.

This article is supported by XENDEE.