Aug 10 2018

Organic Solar Cells

I’ve had a few posts this week that could come off as pessimistic – but there is an upside to these stories. It is true that we don’t currently have enough arable land to feed the world with the USDA recommended diet. We need to continue to improve the efficiency of production and reduce waste. The silver lining is that we have the technology to do this, if we invest in that technology (genetically modifying our crops to have desirable traits) and push back hard against those greenies who are misguided and the organic industry who are trying to demonize a perfectly safe technology.

It is also true that human-caused global warming is happening, we are already seeing negative consequences, and we may be getting close to a point of no return that could cause disastrous outcomes. The good news is that there are technological solutions, if we prioritize them. While we have been pointlessly debating whether or not global warming is real with closed-minded ideologues, energy technology has been slowly but steadily improving in the background. We could, right now, massively reduce the carbon footprint of our energy infrastructure.

We may be getting to a good tipping point – where clean energy is so much cheaper than fossil fuel based energy that everyone is going to want it. We need to make this tipping point happen faster, and we can if we eliminate fossil fuel subsidies (including the subsidy of not charging for the externalized health and environmental cost of pollution).

One technology that offers the hope of a green tipping point is organic solar cells. These are photovoltaic cells (OPV) that are based mainly on carbon rather than silicon. Silicon produces more efficient solar panels, but they are rigid and heavy. Organic photovoltaics can be dissolved in ink and then printed on cheap flexible plastic or other material. You end up with a light, flexible, and cheap solar cell.

The main limiting factor of OPV is that the efficiency – the percent of sunlight converted into electricity – has been relatively low compared to silicon. However, researchers have just pushed the efficiency of OPV into the commercial silicon range.

Silicon PV have an efficiency of 15-22% (the record so far is 27%). Rising efficiency brings down cost, because you get more kilowatt hours of juice per dollar. You can also install fewer panels for your needed electricity. It was not that long ago that silicon PV was struggling to break 12%, but the efficiency has climbed by about 1% per year over the last decade.

OPV recently achieved 15%, which is at the lower end of the commercial silicon PV range. Because OPV is cheaper to produce and install, even at the low end of efficiency this makes them commercially viable. Now a Chinese team has pushed the efficiency of OPV to 17%, deeper into the range of commercial silicon PV. According to the BBC:

This is important because according to estimates, with a 15% efficiency and a 20 year lifetime, organic solar cells could produce electricity at a cost of less than 7 cents per kilowatt-hour.

In 2017, the average cost of electricity in the US was 10.5 cents per kilowatt-hour, according to the US Energy Information Administration.

At 17% the cost would be even cheaper. The researchers believe they can push this technology to 25% efficiency, and given the history of steadily improving efficiency there is no reason to doubt this. But even at 17%, installing OPV on any building to meet its electricity needs is becoming a no-brainer.

OPV also has the potential for many more forms than just roof tiles. Because it is thin, light, and flexible you can put it almost anywhere, such as the roof of an electric vehicle. OPV can be made semitransparent, which means a large skyscraper can have tinted windows that are all OPV. We may be on the cusp of ubiquitous solar power.

The real limitation to widespread adoption to solar is the energy grid. Right now the grid is not set up for distributed energy production. Once a few houses get solar on a block, no one else can until the local grid is updated at a cost of thousands of dollars. Who pays for that upgrade is a good question – right now it’s the consumer. We also need massive grid storage if we are going to make maximum use of solar power.

This is where the government can get involved. First, we need good net-metering laws everywhere, which simply means you get full credit for the electricity you generate and give back to the grid. We also need to invest in an upgraded grid that can accommodate local production and optimize distribution.

The big limitation as I see it is grid storage. We need to build as much of it as we can with existing technologies, such as pumped hydro. We also need to develop newer grid storage technologies. This won’t become a limiting factor for a while, until solar penetration gets to about 30% or so, but we have to start preparing for that now, not wait until it becomes a problem.

Solar is also not the only green energy solution. Wind turbines are also getting steadily more efficient, quiet, and environmentally friendly.

I also firmly believe that if we are going to have the best chance of avoiding a climate tipping point we will need to invest in nuclear power. There has been some positive news on this front as well – the nuclear power industry is adapting to changing demands. There are more engineers specializing in nuclear power, and the industry is designing smaller, more efficient, and safer plants that produce less waste. We can build fully commercial nuclear power plants (meaning they burn all their fuel, and don’t produce material for nuclear weapons), shift to thorium, and reduce costs.

The government needs to streamline the red tape. Further, just build Yucca Mountain already. This is a very safe place to dispose of nuclear waste (actually we can burn a lot of that “waste” in newer plants).

If we adopt a new generation of nuclear plants, update our grid infrastructure, develop grid storage, and properly balance subsidies and incentives to encourage green energy technology and account for existing externalized costs, we can avoid a climate disaster. All we really need is the political will, and that is why climate change denial is so frustrating.

In both agriculture and climate change we have the technology and the ability to solve these massive problems, and in both areas there are ideological campaigns trying to frustrate our ability to do so. But I am optimistic that technological advance will bowl over ideological opposition. The question is how much damage will that opposition do in the meantime.

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