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  • Writer's pictureEvergreen System

Regenerative Hydrogene Fuel Cell


One of the most important and strategic key issues that all nZEB have to deal with are the Energy Storage System. In the near future, staying connected to the electric grid and having the chance to also deal off-grid is going to be a big challenge. Indeed, nZEB have to daily address and manage the intermittent power generation of any FV equipment with a storage system, compared to the electric grid. Something to never forget is that nZEB are strongly involved in the increase of power generated from solar energy and nowadays, one of the most common ways to store on site energy are the Lithium’s RES (RES stands for Residential Energy System).


At Evergreen®, we believe that the Regenerative Hydrogen Fuel Cell (RHFC) would be a great opportunity to change this habit and store environmentally friendly, the excess of solar energy power that we daily need to manage; but what exactly is a RHFC?


Regenerative Hydrogen Fuel Cell System, which will soon be part of nZEB’s technologies, consists of a plug & play station where there are included:

  1. a water electrolyzera

  2. compressed hydrogen gas storage tanks

  3. a fuel cell engine


These three elements combined, by working together thanks to the excess of photovoltaic solar power, will be able to:

  1. generate hydrogen from water (by using the water electrolyzer)

  2. store compressed hydrogen in a high-pressure tank

  3. dispatch hydrogen to fuel cell in order to generate power whenever is required


The document attached is a great professional and technical  analysis of the Energy storage System. A “Net Energy analysis concept” is used to examine some widely installed RHFC configuration, containing alkaline water electrolyzer and a PEM fuel cell.


Comparing RHFC’s technology to other storage ones, they use two energy return ratios: the ESOIe ratio (Electrical Energy Stored on Invested) where, as the experts say, “the ratio of electrical energy returned by the device over its lifetime to the electrical-equivalent energy required building the device”; and the overall energy efficiency that is “the ratio of electrical energy returned by the device over its lifetime to total lifetime electrical-equivalent energy input into the system”.


In the original document’s reference scenario, it is shown that the RHFC system has an ESOIe ratio of 59, more favorable than the best battery technology available today (Li-ion, ESOIe = 35).


Click here to read or download the article

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