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Four (more) renewable energies you may not have heard of: solar edition

Randy Montoya/ Sandia Labs/ Flickr

93 million miles away, burning at 100 million degrees, is the largest nuclear fusion reactor in the solar system. 

And we’re barely using it. 

In one hour, more solar energy hits the earth than humanity consumes in an entire year; but solar power only accounts for 0.4 percent of energy used in the United States annually. 

The solar energy that hits one square mile over the span of a year is equal 4 million barrels of oil. That one square mile could power the entire world for 24 minutes.


So why aren’t we doing something with it?

The main argument against solar power is the efficiency. Most solar panels just aren’t efficient. On average, commercial panels convert only 10-15% of the energy hitting them into energy. They can also be expensive, a pain to install and can only face certain directions. 

But those arguments are quickly becoming invalid. As I’ve previously discussed, all around the world people are making strides in the field of renewable energy. 

And solar may be the most exciting.

See-through photovoltaic cells

When people think of solar panels, chances are, they’re thinking of photovoltaic (PV) cells. 

These big, chunky blue panels are traditionally silicon based, and have been used since the late fifties to power things such as satellites and those calculators from the 90s that never needed batteries.

PV cells are the most widely used type of solar panels, but the problem is that in ideal conditions, they can only harvest about 24.2 percent of the sunlight hitting them--the average of 10-15 percent is much more common. And then when you’re limited to putting them on rooftops that face south, the problem compounds.

But what if every window in your house was a solar panel? Transparent photovoltaic cells may make that a reality.

Screen Shot 2015-11-25 at 11.27.33 am.pngA clear solar cell
Image: Ubiquitous Energy

Traditional photovoltaic cells are made up of semiconductor materials such as silicon or copper. These materials are integral to solar power because they react to sunshine to produce electricity. The semiconducting material is layered over itself to capture as much energy as possible.

At first glance, a transparent photovoltaic shouldn’t work, because PVs absorb sunlight to create electricity. If no sunlight is being absorbed, logically, no energy can be captured. 

But what about invisible light? 

In 2014 scientists from the University of Michigan unveiled their transparent PV cells. These PVs work by making two, fundamental changes to the traditional design. They changed the type of light they used, and they moved the semiconducting material from the back of the cell to the edges.

Let me explain.

First, they harness infrared light waves, instead of the visible light that we rely on to see. To do this, they use a “transparent luminescent solar concentrator.” This see-through material contains organic salts that absorb invisible light waves and converts them to infrared waves. It then redirects those infrared waves horizontally toward the edge of the cells. 

Second, the light sensitive material has been moved to the edge of the cell to absorb this newly redirected light. It’s this change that truly allows for the cells to be see-through--there’s simply nothing there to obscure vision anymore. Together, these changes permit visible light through the cell, while utilizing the invisible light waves of the spectrum.

Ubiquitous-Energy-Schematic1.pngSchematic of the design
Image: Ubiquitous Energy

It’s a case of the whole being greater than the sum of it’s parts. Neither change would work individually, they have to be used together.

This technology could be used to replace windows in skyscrapers, making them pay for themselves. As anyone who has worked directly next to a window 50+ feet in the air knows, it gets really hot. Contractors already use windows that reflect and reduce sunlight penetration, so moving to see-through photovoltaics cells shouldn’t be too much of a stretch.

Space solar power stations

One of the biggest drawbacks of solar power is that when it’s cloudy, you’re not generating much energy. But what if there were a way to completely circumvent cloudy days altogether?

Enter the Japan Aerospace Exploration Agency, or JAXA. 

JAXA has been working on a concept they call Space Solar Power Stations. These stations will live more than 22,000 miles above the Earth in a geosynchronous orbit, absorbing sunlight almost 24 hours a day. The power plant would then send the power generated back to a station on earth. 

NASA Johnson.jpgImage: NASA Johnson/ Flickr

This concept of orbiting solar power stations is both very new, and very old. The idea was first conceived by Isaac Asimov in 1941, in a short story called Reason, in which two humans live in a solar space station orbiting earth. 

Fast forward to 1968, when American aerospace engineer Peter Glaser discussed the potential for gathering solar energy in space. In his article, titled Power From the Sun: Its Future, Glaser said “Solar energy is basic to man’s continued survival on Earth… Because we have coal, oil, and natural gas, the tremendous potential of solar energy has not yet been harnessed. Whether or not the human species will continue to expand could depend on our ability to develop alternative energy sources.”

Glaser’s original design for the space solar power station called for several satellites, miles wide, to be constantly circling the earth. These satellites would then beam the power back using microwaves to receiving antennas five miles wide. Glaser conceded that at the time, the technology needed to harness solar power on that magnitude was still being developed; however it wouldn’t be long before the potential of solar power was recognized.

Space_to_ground_microwave,_laser_pilot_beam.jpgAn early concept drawing.
Image: NASA/ Wikimedia

Fast forward to now, and the technology is being developed. 

In March of 2015, Japan successfully demonstrated technology to transmit power wirelessly from one point to another.

Researchers converted 1.8 kilowatts of Direct Current electricity into microwaves, and sent it through the air to a receiver 170 feet away. The receiver then converted it into alternating current electricity, which could in turn be fed into the electric grid.

This is absolutely huge. 

Wireless energy transference has been a technological pipe dream since the theory was first made popular by Nikola Tesla in the early 1900s, but it hasn’t really achieved feasibility until now. This was the missing piece to the puzzle. We could get the PV cells out in space, we could build the plant, we could keep it floating right where we need it to, but we needed a way to transfer that generated power. Now we have it. 

While this station is still a long way away, JAXA has the technological roadmap already established. They hope to have a 1-gigawatt plant (about the same output as a nuclear power plant) in space by the 2030s. 

Solar roadways

As I’ve discussed in a previous article, roads absorb an insane amount of sunlight and energy. Right now, that energy is doing nothing other than heating up our cities. But one engineering couple thinks that should change. 

Julie and Scott Brusaw are co-founders and co-inventors of Solar Roadways. You may remember hearing about them briefly from social media, as their Indiegogo campaign video, Solar FREAKIN’ Roadways, went viral. 

Solar Roadways 1.jpgImage: Sam Cornett/ Solar Roadways

But don’t let them fade from your mind. There’s a reason Solar FREAKIN’ roadways got almost 21 million views. 

Because it’s an incredible idea. 

The design is a relatively simple one. Modular, hexagonal PV cells are fitted together underneath extremely strong, textured custom glass to create the road’s surface. The cells feature heating elements to melt snow, and LED lights that can be programmed to display almost any message, from “slow down” to “accident ahead.” 

The underground structure sheltering the roadway’s electronics can house cable and telephone wires, while also capturing and filtering stormwater. The design seems great, but Solar Roadways is still in its second prototype phase. 

solar roadways prototype.JPGThe second prototype

Good thing Solar Roadways isn’t the only company working on this concept. Solaroad, a company based in The Netherlands, installed its first solar roadway on a 70 meter stretch of bike path outside of Amsterdam in November of 2014. Six months later, that stretch is generating enough power to provide electricity for a small home. This is much better than what they had hoped for. “We did not expect a yield as high as this so quickly,” said Sten De Wit, spokesman for Solaroad in a statement. 

There’s an estimated 29,000 square miles of road in the United States. If every road were replaced with solar roadways, we’d be able to produce three times the amount of energy we’re currently using. Now, while that does sound amazing, the project would cost an estimated $56 trillion USD to accomplish. 

That’s too much. But if even a fraction of that were implemented, the results could be amazing. And prices will inevitably come down in the future. Plus, roads in the US are falling apart. 

Artificial photosynthesis 

What if there were a way to take sunlight, water and carbon dioxide and make energy out of it? Currently, it seems like Nature has the only blueprint for photosynthesis, but that may be changing. All over the globe scientists are working on way to artificially replicate photosynthesis. 

Plants around the world turn 1.102 trillion tons of CO2 into organic matter annually, using only 3 percent of the sunlight that hits Earth. That’s incredible. If humanity wants to come anywhere close to that, we’re going to need to break two fundamental barriers. To achieve photosynthesis, an artificial system needs to be able to absorb sunlight, and split water molecules into something usable. 


Plants have had hundreds of millions of years to perfect this system, and they do a super job. They’ve developed proteins and enzymes that use sunlight to break down H2O molecules into carbohydrates and oxygen. 

Humanity is trying to do this, but with a different output. Ideally, an artificial system would be able to drag CO2 out of the atmosphere and efficiently produce liquid hydrogen. Liquid hydrogen is often considered the ultimate renewable energy source, because it contains no carbon, and therefore is unable to release the greenhouse gas into the atmosphere. 

Good thing we’re getting close to that goal. 

One of the biggest hurdles in achieving artificial photosynthesis is finding an efficient and cheap way to split water molecules into hydrogen and oxygen. Scientists have been working on finding the best catalyst for this complicated molecular process--and recently, they found one. 

For a system of artificial photosynthesis to be considered a success, it needs to reach an energy efficiency rate of 10 percent. Recently, researchers at Monash University in Melbourne, Australia, have achieved a rate of 22.4 percent, using nickel as a catalyst. 

This is great because other catalysts are fairly expensive to create or find, whereas nickel is abundant and cheap. Their system is also able to run on river water, which significantly expands the potential locations for this sort of system to be implemented. 

home made leaf.jpgA sample of a photo electric cell in a lab environment. Catalysts are added to the cell, which is submerged in water and illuminated by simulated sunlight. The bubbles seen are oxygen (on the front of the cell) and hydrogen (on the back of the cell)
Image: MisterRichValentine

Although these are still the first few steps of unlocking the vast potential of artificial photosynthesis, the first steps are the hardest. With forests of artificial trees, we could start working on not just reducing output of green gases such as carbon dioxide, but actually lowering their levels. 

Which is good news, because the need has never been more dire. More carbon is being released into the atmosphere now than in our planet’s history, and as countries still lean on the crutch of coal and fossil fuels, that rate is going to continue to increase. There needs to be an open dialog on the subject. 

Renewable energies are how we’re going to power the future, from massive solar stations orbiting the planet, to man made trees absorbing carbon from the atmosphere. With the induction of better forms of energy storage, and zero emission vehicles capable of running on hydrogen, a greener planet is closer than ever. 

Solar power is going to light the way to a brighter and better tomorrow. Just don’t forget the sunscreen.