Solar power isn’t perfect, but it’s about as perfect as we can get if we need heat or electricity and don’t want to generate emissions by burning carbon-based fuels (coal, oil, gas) or hazardous waste from nuclear power plants. Here we’ll see what is going on with solar technology- the good, the great and the horrible.
As a preview, here are some of the key issues: solar energy isn’t pollution free because the manufacture of solar cells and their contents can cause significant environmental damage on site, as can the mining of minerals used to improve the properties of solar cells. Problems of these types have been documented extensively for the solar industry in China, which is a major supplier of amorphous silicon and other materials used in solar cells.
Are there alternatives to all of this pollution? Yes, there are. European manufacturing techniques prevent pollution associated with processing silicon, for example, but (of course) some investment is needed to install the necessary equipment and carry out the necessary extra steps. I discuss these more below.
Other alternatives- do they exist in the solar arena? The answer again is yes. If you live in the right climate, you can use direct solar heating of water in a number of ways, for example as an alternative to heating water with natural gas or electricity derived from fossil fuels or nuclear power. “Industrial strength” versions of this approach include the use of solar concentrators that can really focus energy from the sun right where it is needed.
I hope this has you intrigued enough to read further. All sources are cited and all writing is original unless a source is given. In some cases, I try to interpret an article for you, and yes, I am a trained scientist, though that doesn’t mean I’m always right, so feel free to disagree and we can discuss any point you like.
Ask questions if you have them, either in the guest book or by contacting me.
I’ll post key stories, links, blogs, resources, and comments, and offer my own commentary on solar energy-related issues. Discussion is definitely encouraged and welcome. Please sign the guest book and comment!
Hydrogen and Oxygen gases can be used in fuel cell technology to provide energy to a home, for example, and the gases can be produced by the action of sunlight on water with the help of certain solar cells, or photovoltaics, and additional components known as catalysts. This means that solar energy can be used to power a home (etc.) during the day by generating electricity, and excess electricity could be stored in various ways.
Please note that Sam Carana has written a lot about the hydrogen economy, and he covered this same story, but with more technical information about the new science and catalysts, here.
Batteries are typically thought of for storage of electricity, but another option is offered by the power of sunlight: energy storage through generation of hydrogen and oxygen by the process known as electrolysis. Electrolysis can be made more efficient by catalysts, and a new, breakthrough catalyst has just been discovered:
As described by Mariella Moon of ExtremeTech, “… one catalyst would be responsible for producing oxygen gas from water, while another would produce hydrogen. The hydrogen and oxygen could be recombined in a fuel cell to power the home at night where solar energy isn’t readily available…”
Hydrogen and oxygen would accumulate during the day from excess electricity capacity of a solar cell system, and then these gases would power a fuel cell that would, in turn, power a house overnight. The byproduct of the fuel cell, water, could then be re-used for water splitting the next day.
Illustrations of the idea and video from principle scientist D. Nocera of MIT is shown at the GoodCleanTech site, the Green Blog of pcmag.com, as posted by Mariella Moon.
The key to this new catalyst is that it does not require expensive metals like platinum, yet it works at atmospheric pressure, room temperature and moderate pH.
Solar cells/solar panels- how do they work? A very basic and preliminary, conversational intro.
“On Solar Cells” © James K. Bashkin, 2008
All solar cells work in basically the same way (there are really two basic ways, but the technicalities aren’t important to this discussion, at least yet).
Semiconductors are the key, and these materials are characterized primarily, to a first approximation, by their composition (like gallium arsenide or indium phosphide) and band gap. The band gap can be thought of as the amount of energy, such as the energy supplied by a photon (light), that is required to promote an electron from the nonconducting valence band to the conduction band. Quick definition: photon, or particle of light, refers to the particle side of light’s wave-particle duality.
Manufacturing techniques can vary significantly for solar cells (solar panels), some being very complicated, involving the careful growth of crystals on top of other crystals under high vacuum conditions, and other techniques being as simple as spraying or painting a few payers of paint or ink. A lot of clever invention went into all of these designs.
One important idea relevant to this discussion is Einstein’s photoelectric effect. However, photocells were discovered experimentally before the photoelectric effect was proposed, and the photoelectric effect was actually proposed theoretically before equipment was good enough to prove it was true, experimentally. I realize this sounds like a circular argument, and it would be if the photoelectric effect and photocells were exactly the same the thing, but they aren’t. The photoelectric effect describes how light can eject electrons from metals and other substances. Photocells are made of nonmetallic semiconductors that are not conductors but can be turned into conductors under the influence of absorbed photons. For photocells, light doesn’t eject electrons but causes charge to flow, or electricity to be generated and conducted through the material.
One of the design issues is how to make photocells that use the solar spectrum efficiently. This is one of the reasons why a variety of materials and approaches are used, and often combined. to give a final panel design. It also helps explain why photocells for satellites have different requirements than photocells for earth: the atmosphere around earth absorbs light, as you know, and this changes the available solar spectrum vs. what is available in space.
Once a semiconductor absorbs a photon (or several), it becomes a conductor. However, the efficiency of charge conduction (electrical conduction) is related to things like how many so-called charge carriers are available, the mobility of these charge carriers through the material, and to the ability of the material to avoid what is called recombination, where the + and – charge recombine, giving off heat and no electricity, and therefore waste the absorbed photon.
Much of the elegant design of natural photosynthetic systems has evolved to maximize efficiency and minimize nonproductive recombination.
Does any of this help?
Note to cherished physicists, chemists, et al., please offer corrections if you like, but please consider that I will make this continuing discussion more sophisticated over time, with additional installments and even references/literature citations! So far, it is just off the top of my head, as it were. I would appreciate it if you would distinguish between oversimplifications and true errors. The latter I’m glad to hear about while the former is here on purpose, to help people without technical training develop some sense of how solar cells work.
Since I have a love of the arts, literature and music in addition to my strong feelings about the environment, I was delighted to find author, Classic, who is prolific and a pleasure to read. Read Classic’s website Albatross, for example!
For more about what I’m up to: I operate at DIGG, Reddit, bloggingzoom, blogcatalog, gather.com and a few other sites I can’t think of now under the name chemrat. My main blogs are Nearly nothing but novels: fiction and crime fiction book reviews and Chemistry for a sustainable world. There is some good environmental discussion in the comments at gather.com, along with good articles by many (SamCarana and Steve B. being two who have a lot of specific information on energy issues).
I am excited about a new service, GoGreenSolar, which operates all over the US and in many parts of the world, that helps you find installers of solar and wind power, including competing bids, and gives lots of detailed advice on the various choices and tax rebates. It works based on your zip code/post code, along with specific information about your home or other building of interest. I bring it up here because I have had countless requests for specific information and advice about installing solar power, both solar heating and solar panels for electricity.
I have a strong statement to make about alternative energy. I find that it is easy to make the case for moving away from carbon-based energy sources (coal, oil, natural gas) for reasons of pollution, health and global stability without referring to Global Warming. I say that not because I dispute Global Warming (quite the contrary), but because I’ve found many people who are emotionally invested in various anti-Global Warming positions (as in GW is a conspiracy of “left-wing anarchists”). However, these same people will in many cases completely buy into the idea of alternative energy for reasons that air pollution, toxic waste, war, and many other problems can be attributed to fossil fuel use.