After catastrophic wildfires in 2017 and 2018 had devastated the transmission lines owned by PG&E Corp., it was forced to declare bankruptcy. And the fallout from that has been a move to localize both the supply and delivery of electricity — power to come from green energy and to be sent using microgrids.
Microgrids are set up for several reasons that include increasing a region’s resiliency — or its ability to maintain power as well as incorporating more renewable energy to cut down on CO2 releases. And they can be set up in remote locations that have no access to the centralized grid, thus creating more economic opportunities. But in the case of PG&E, it is looking to such localized delivery systems as a way to battle wildfires and to avoid wholesale blackouts.
“In the last decade, renewable energy sources have been transforming the microgrid landscape, consequently reducing or even eliminating the need for costly fossil fuels. This has been made possible through the use of hydrogen,” says Thomas Chrometzka, a strategist with Enapter, which makes electrolyzers — a device used to split apart the hydrogen and oxygen from water. “Introducing hydrogen to microgrids solves the problem of seasonal or long-term storage that batteries cannot provide. It is the crucial jigsaw piece for 100% green microgrids.”
Let’s take a step back: When most people think of a microgrid, they visualize a hospital or a campus that is powered by rooftop solar panels. That electricity is then sent via the mini-grid to the buildings. Not only is it green power but it can also be independent of the utility or it can kick on when the central power cuts off. But to keep on the electricity at night, the excess solar power is stored in a battery, which discharges when the sun is not shining.
Battery storage is economic because it can displace peaker plants, or those generation facilities built to serve high demand. It can relieve grid pressures during periods of high demand, which means that utilities do not have to procure expensive power or build new generation units.
But batteries have a critical shortfall, which is that they cannot provide long-term storage. That is, they can charge and discharge, keeping the electrons flowing for limited periods. If a catastrophic event such as a wildfire occurs, then such things as diesel generators are used for long-term relief — but limited by the amount of available fuel.
Enter hydrogen, which can be stored at high densities while leaving a low-carbon footprint. Using a fuel cell, that hydrogen will produce electricity for sustained periods.
In other words, the solar panels are producing excess electricity that must be stored in a battery and used in an electrolyzer to create pure hydrogen gas. That gas is then stored in a tank before it is piped to a fuel cell, which uses the hydrogen to create electricity. If solar power is used, it called “green hydrogen.” The goal is to ratchet down the cost of that process. While solar costs have dropped by 85% over 10 years, the focus now is on achieving economies of scale for electrolyzers.
“Batteries are a short-term solution to a long-term problem,” says Chris Allo, president of ElektrikGreen, which is a Colorado-based developer of hydrogen-based power storage solutions. “They work for temporary outages and they wear out. With hydrogen, I can fill a tank and empty a tank a million times. If I need more storage, I add more tanks. If I run out of hydrogen, then I use a battery.”
How does this work in a microgrid? A community center, a fire department or a medical complex would store hydrogen on-site while also using fuel cells. Those enterprises could operate independently, although if they generated more electricity than they could consume, they could send some of it back to the utility via the grid. It’s tantamount to having a diesel generator but there are no emissions.
But what about the cost? Storing the hydrogen in tanks is price effective. But the businesses still have to purchase an electrolyzer and a fuel cell to discharge the electricity. ElektrikGreen’s Allo says that such hydrogen systems are “affordable,” especially because they come with a 30% credit from the U.S. government. The return on investment takes between 10-15 years and it comes from energy savings. Beyond that, it gives customers peace-of-mind that they will never lose power and that they are not contributing to carbon emissions.
Consider Cirque de Mafate, which is a remote island in the Indian Ocean where 700 people live. It is powered by rooftop solar panels and electric batteries as well an electrolyzer for hydrogen production and a fuel cell to discharge the resulting electricity. The hydrogen is stored in tanks that can provide power for 10-days at a time — a technology that is replacing the need to use dirtier diesel generators.
“Hydrogen is simple and it is in its infancy when compared to battery storage,” Allo says. “Batteries are the first step on the lily pad to allow us to separate from the grid. Microgrids in the U.S. are mainly battery-based systems because that is now popular. But green hydrogen produced from solar is the future. There will be incredible growth and it is the next step in storage.”
Microgrids are proliferating to help businesses and communities become greener and more resilient. Their long-term future, though, is linked to the production of clean hydrogen, which is ultimately converted into electricity and is used to maintain electricity flow for long periods — a benefit that has untold value to communities devastated by disasters.
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