The Intertubes are abuzz with news of yet another new clean tech breakthrough that spells yet more bad news for coal and natural gas power plants. The new “solar flow battery” is aimed at lowering the cost of solar power by combining solar collection with chemistry-based energy storage in one integrated system. The new system also fits neatly into the resilient, distributed, diversified grid envisioned by the US Department of Energy.
Wait — what? The Department of Energy is envisioning a resilient, distributed, diversified grid? What about coal and natural gas? Quick, somebody warn the White House!
Going With Energy Storage Flow
Before get into that thing about a rogue Department of Energy, let’s take a look at flow batteries.
For those of you new to the topic, a flow battery is based on the movement of liquids. In a typical flow battery, two moving liquids produce an electrical current, when separated by a thin membrane (or no membrane, as the case may be).
The two liquids are stored in separate tanks until called into action. The battery discharges when the two liquids are pumped together in a stack. To recharge, you send the liquids back to their respective tanks.
On the plus side, flow batteries constitute a remarkably simple energy storage technology. Since the two liquids are stored in separate tanks, there is no loss of charge over time. And, scaling up is just a matter of larger tanks along with more pumping capacity and other equipment.
As for negatives, scaling down while cutting costs used to be the problem.
Until recently, flow batteries were large, bulky affairs with relatively little practical application. Now a new generation of leaner, more efficient, and less costly flow-based energy storage is finally emerging.
Why A Solar Flow Battery?
If you could integrate a solar cell into the system, you could ramp up the efficiency, which means your energy storage device could be smaller and cheaper.
That’s the idea behind the new solar flow battery, a collaboration between University of Wisconsin-Madison chemistry professor Song Jin and Jr-Hau He, a professor of electrical engineering at Saudi Arabia’s King Abdullah University of Science and Technology.
Don’t get too excited just yet — the new flow battery uses a rather pricey solar cell, so there are a few more steps before the device can reach the mass market.
However, the scale is right. Instead of a house-sized arrangement of tanks and pumps with a field of solar panels attached to it, the collaboration has yielded a compact device that measures mere inches across.
You can get all the energy storage details from the study, published in the journal Chem under the title, “14.1% Efficient Monolithically Integrated Solar Flow Battery” (14.1% is a new solar conversion record, btw).
The researchers point out that storing solar energy in chemical bonds is not a new thing. Photoelectrochemical reactions are the principle behind “splitting” hydrogen from water using an electric current provided by solar power. And, reversible chemical reactions are the basic principle behind rechargeable batteries.
Here’s the money quote
…the PEC [photoelectrochemical] solar energy conversion process can be seamlessly connected with rechargeab le batteries by the common reversible redox reactions they share to realize an integrated device that can be directly charged by solar light and discharged like normal batteries when needed.
As for cost, that’s one of the next steps for the research. The research team used a species of expensive multilayer solar cells to demonstrate proof of concept, and they are already looking to bring the cost down to earth:
…the cost of III-V cells may be reduced in the future by designing simpler tandem cells with a sufficiently high photovoltage or adopting new fabrication methods, such as epitaxial liftoff. With further developments and proper device design following the design principles laid out herein, we believe that the capital cost for monolithically integrated SFB [solar flow battery] devices will not be higher than individually operated PV [photovoltaic, aka solar cell] devices plus RFBs [redox flow batteries].
The Sparkling Green Grid Of The Future
So, here’s where things get interesting. The new solar flow battery can operate in three different modes.
In addition to storing solar energy, it can provide electricity directly from the solar cell. It can also be recharged from any other source of electricity.
That source-neutral capability means that the new solar flow battery would complement other types of renewable energy, fostering improved grid reliability.
So, what does that mean for fossil fuels? Despite all the tough talk about bringing coal jobs back to the US, the Trump* administration has been powerless to stop the shift away from coal power generation in the US.
It’s worth noting that natural gas is also beginning to show signs of wilting under pressure from renewable energy. The difference is that the President did not campaign on a platform of bringing back gas jobs. He promised to bring back coal jobs.
So, why are the coal jobs not coming back? Market pressure is the main issue. The nation’s fleet of coal power plants dates back to the 20th century. Like any other major infrastructure, they are aging out.
The simple fact is that power generation stakeholders are taking a look at the cost of upgrading old coal facilities compared to replacing them with new 21st century resources, and it looks like renewables are coming out on top.
Another issue is grid resiliency. The nation’s energy policy has been shifting away from the centralized power generation model. This movement toward a more integrated, diversified grid has grown in tandem with the development of new technologies that support distributed energy generation, including renewable energy and energy storage.
Putting it all together is the Department of Energy’s Grid Modernization Initiative, which just wrapped up its 2018 peer review last month.
Among the 90 or so projects under the initiative’s umbrella, some are specifically aimed at helping states reach their renewable energy goals.
The initiative links all of the agency’s offices plus its network of national laboratories, including the National Renewable Energy Laboratory, which is looking forward to “high penetration of clean DER and emerging grid technologies.”
CleanTechnica is reaching out to the agency to see if a wrapup of the peer review is available, so stay tuned for more on that.
Meanwhile, that’s just a small sampling of the Energy Department’s efforts to accelerate renewables at the expense of fossil fuels.
Old coal mines may get a fresh start as new solar farms, but coal jobs are never coming back.
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Photo (cropped, enhanced): “This image shows a new integrated solar flow battery with a 14.1 percent efficiency” by David Tenenbaum, UW-Madison.