“Radical Polymers” Could Fuel Next Solar Technology Spike

October 11th, 2014 by Tina Casey

Here we go again. Partly fueled by the booming fossil fuel industry in North America, the price of oil is taking a nosedive, and out come the wagging fingers to say that solar technology will never be able to compete.

What was that thing about being doomed to repeat history? Compared to solar energy, the global petroleum market has about as much built-in stability as a spinning top, and long term prices have been going up even as drilling technology advances. Meanwhile the trend in the cost of solar energy is down, down, down, partly due to some spectacular advances in solar technology.

That’s because once you get the latest solar technology into the ground (or onto your roof or wherever), you’re not going to see an upswing in the price of sunlight. That brings us to the latest development in high tech, low cost solar energy: radical polymers.

Radical Polymers and Solar Technology

Radical polymers refers to a particular family of polymers (aka plastics) that can conduct electricity.

If you’re familiar with organic solar cells (here’s another example), you can already see the potential for radical polymers to yield low cost, flexible, transparent solar technology that could be applied to just about any surface, including windows.

That’s the goal set by a research team at Purdue University, which has just announced the results of their work on a radical polymer called PTMA.

For those of you keeping score at home, PTMA is short for poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl meth- acrylate). Previous research has demonstrated that PTMA holds some promise, since it is about 10 times more conductive than other types of semiconducting polymers.

As for the cost, think of it in terms of Plexiglass and you’re on the right track. Here’s how assistant professor Bryan Boudouris sees things shaking out (you can check out his solar technology podcasts, too):

We make billions of tons of plastic every year. So imagine if you could produce that same kind of material at that same scale but now it has electronic properties.

The Long Road To Cheap Solar Technology

Don’t hold your breath for your local dollar store to stock superconducting Plexiglass solar cells that will bring virtually free energy to your doorstep any time soon, because the Purdue team is aiming for an increase in conductivity of about 100 to 1,000 times before commercial applications are viable.

With that in mind, let’s take a closer look at the Purdue study, which was recently published in the journal Macromolecules.

For those of you new to the topic, radical polymers belong to a class of polymers that have small offshoots, called pendants, hanging from a long central chain of molecules.

The pendants are where the conductive magic happens, so the trick is to modify the electronic properties of the pendant for maximum efficiency.

Here’s how Purdue describes it:

To create the radical polymer, the researchers used a procedure called deprotection, which involves replacing a specific hydrogen atom in the pendant group with an oxygen atom, converting it into a so-called radical group.

As a result of the deprotection step, the team identified two properties of the radical property that could provide a pathway to increasing its conductive properties.

We Built This New Solar Technology!

You don’t normally see the Department of Defense mashing up with anything that has “radical” in its name but DoD has been all over cutting edge solar technology like white on rice, so in this case it’s no surprise to see a couple of DoD offices pop up in connection with the Purdue study.

In addition to the National Science Foundation, the Air Force Office of Scientific Research and the Defense Advanced Research Projects Agency have also chipped in funds for the Purdue radical polymer research effort.

Along those lines, let’s note that earlier this week one of our favoritest DoD renewable energy programs, the Army Energy Initiatives Task Force (EITF), has transitioned into a permanent office just three years after its launch in 2011.

EITF hasn’t been waiting around for the latest cutting edge solar technology to leap from the lab to the backyard. Focusing on utility-scale renewable energy, the newly named Office of Energy Initiatives (try oei.army.com if the previous link isn’t up and running yet) already has a number of projects under its belt and more in the pipeline.

Taxpayers pay nothing up front because it’s all being done under power purchase agreements. The Army just pays for the renewably-sourced electricity and gets built-in price stability to boot, along with locally sourced power that can buffer against grid disruptions.

However, staffing the office takes seed money and manpower, and that’s where things could get bottlenecked if the party of Support our Troops decides to blow the federal budget up again this year.

In a media roundtable on Army energy last week, Katherine Hammack, assistant secretary of the Army for Installations, Energy and Environment, made it clear that budget cuts haven’t been doing the program any favors, so stay tuned.

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