Solar Power without the Sun

Christopher Talerico's picture
Christopher Talerico
April 30, 2016

Scientists in China are hard at work developing solar panels that can generate electricity through the power of rain.

A new technology that could revolutionize solar power has been developed by a team of scientists from Yunnan Normal University and the Ocean University of China who utilized one of the lesser known qualities of the super material known as graphene.
A new technology that could revolutionize solar power has been developed by a team of scientists from Yunnan Normal University and the Ocean University of China who utilized one of the lesser known qualities of the super material known as graphene.
Credit: Wikimedia

Solar power in general is no longer news. The slow but steady climb began in earnest in the late 90s but has come to dominate the renewable energy sector. Granted, this may differ depending on the metric you use.

It's difficult to argue that solar power hasn't been stealing headlines. This is only bolstered by the fact that green building standards, such as BREEAM and LEED, award a significant number of points for the use of solar power and energy efficiency. Indeed, LEED's Energy & Atmosphere category, which addresses solar and efficiency, awards the most certification points of any category.

The attractiveness of solar power, and potentially its strong inclusion in green building standards, is made clear because the amount of energy we could harvest from the sun is somewhere around 5000 times the total amount of energy the world currently consumes. 

The Rise of Solar Power

In total megawatt hours (mWh) of energy produced globally in a single year, wind power still leads the pack. However, solar energy is not far behind and quickly catching up. It is only a matter of time before solar becomes the preferred renewable energy source.

Of course, that would require covering all available land space with solar power collecting products. Still, the amount of land necessary to cover the United States’, a major industrialized nation, energy needs at current conversion rates is roughly 1/60th of the country’s total land mass—or half of Colorado.

By 2015, the cumulative global capacity for wind powered renewable energy sources was just a little bit over 432k mWh, or 432 gWh. Conversely, by 2015, global solar power produced less than half of that amount reaching the coveted 200 gWh, or about 1% of the global energy demands.

Graphene, Sketchport

Solar Power: Even Rain in or Shine?

A new technology that could revolutionize solar power has been developed by a team of scientists from Yunnan Normal University and the Ocean University of China who utilized one of the lesser known qualities of the super material known as graphene.  

Graphene is essentially just carbon molecules, except the molecular structure is formed in the shape of a spheroid, hollow cage, and is only one atom thick—forming a hexagonal honeycomb lattice. Aside from being 100-300 times stronger than steel, it is also the thinnest and lightest material known to man.

Another quality of graphene, the one that the Chinese scientists utilized, is its ability to interact with the positively charged ions present in different salts in rainwater. These ammonium, calcium, and sodium ions engage with the electrons of graphene, and viola, you have electricity.

Because graphene also is one of the most conductive materials known to man, this breakthrough makes it possible for solar panels to be effective even when the sun is obscured by storm clouds.

However, this is not the only green design advantage this development offers.

Graphene is also an exceedingly inert material so it will not interact with most other materials it comes in contact with. For solar energy applications in rainy weather, this can serve double duty. While the graphene’s electrons may interact with the salt ions in rain, the molecular structure does not change. That is, the salts do not bond with the graphene.

However, while the salts will not corrode or bond with the graphene, the rain will “stick” to the graphene’s surface and essentially create what is known as a pseudocapacitor. Through this attractive function, the rain will either remain on the panel or flow off of it once a saturation point is reached.

Thus, the rain that strikes the solar panels can be collected, and for those projects seeking the LEED BD+C Sustainable Sites Rainwater Management credit, if the solar panel array occupies a large enough area, this may make significant contribution towards outdoor water use reduction--especially if drained into a cistern or diverted for use in irrigation.

Unfortunately, at this point, the 6.5 % conversion rate or graphene in solar applications pales in comparison to even the more inefficient conversion rates of solar panels in direct sunlight, which is roughly 10%. However, considering the relatively untapped and unstudied potential of graphene used in conjunction with solar panels, better conversion rates are almost certainly possible. 

If solar panels can be adapted into a more complete renewable energy generation system that does not rely exclusively on the availability of sunlight to supply enough power for major industrialized regions, it is quite possible graphene could increase the effectiveness of solar by generating electricity in times of rain, even when it would otherwise not be possible. As such, solar-hybrid systems could quickly become the renewable energy choice for most any region and overtake the other renewable energy sources utilized—especially relevant for wind power. 

Solar Panels, Wikimedia

Overcoming Obstacles

While solar power has a bit of a steep climb before it can catch up to and overcome wind power as the most productive renewable energy source, the continued development of solar panels to be more efficient while also harnessing other means of generating electricity may help push it over the top.

But for some regions, the reticence to shift to solar is more practical. Unless you live in a region that receives a great deal of sunlight, you may not see the kinds of benefits from solar power that make it a more attractive renewable energy source.

Thus, with the ability to harness more total energy, continued advances in the conversion rate of sunlight to usable electricity, and now the production of energy when sunlight is not available, solar power--or some version of hybrid solar panels--has little in the way of competition as the king of renewable energy.


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