Rise in Awareness of Electricity Conservation, Home Solar Power Systems Seen after Earthquake in Japan

Image by okadots. Some Rights Reserved.


Housing Company, part of the Sekisui Chemical Group, released on August 18, 2011, the results of its post-disaster survey targeting owners of photovoltaic (PV) power generation systems. In the aftermath of the Great East Japan Earthquake in March, having encountered power supply failures and rolling blackouts in many areas, respondents showed that they had greater awareness the capacity of their PV systems to provide a supply of electricity for their own use on fine weather days. (The systems are normally set to provide power directly to the power grid instead of for the owner's own use.)

According to the survey, 80 percent of respondents "knew how to use a PV system in the stand-alone mode," while those who actually switched to this mode accounted for 67 percent in quake-hit areas and 33 percent in areas hits by rolling blackouts. Among those who used the stand-alone mode, the majority (86%) said used the power to charge mobile phones, followed by rice cookers (51%), and televisions (40%). Some also reported that sharing electricity with neighbors contributed to better neighbourly relations.

Meanwhile, the Group's Housing Environment Institute released on August 22, 2011, the results of its survey on awareness and electricity conservation behavior of PV users after the earthquake. The results show that more people were eager to save electricity afterwards compared to the same survey conducted before the quake, in January 2011.

The survey also showed (1) that people tended to more actively try to save electricity after the earthquake; (2) that compared with the general population, PV users reported having lower stress about power-saving efforts and saved most power at peak power consumption times of the day; (3) that interest in PVs has been increasing, especially in eastern Japan; and (4) that interest in storage batteries and learning life skills for power-saving have been boosted.

Sekisui Chemical Achieves Record with Home Photovoltaic Installations (Related JFS article)
http://www.japanfs.org/en/pages/026771.html

SOLAR HYDROGEN POWER FOR HOMES

 by Bruce Mulliken, Green Energy News

Utility companies need not lose any sleep: It will be a long time before significant numbers of homeowners in the industrial world will be able to disconnect from the grid. While the cost of generating power from intermittent renewables, such as solar and small wind, may be dropping (with generous government incentives to help), the cost of storing power is still prohibitively high. If intermittent renewable energy can’t be stored then the power cable between home and grid can’t be disconnected.

(Lucky the developing world, though. Where there is no power grid, the norm of the future may be to install independent home generating stations rather than build a formal power grid infrastructure. If so, the developing world will have the green state-of-the-art power system while the industrial world will keep its outdated, inefficient, dirty, centralized power distribution system.)

Batteries, for the time being, are currently in the forefront of energy storage for homes. But, Sun Catalytix of Cambridge, Massachusetts thinks a better solution would be to use electricity from solar photovoltaic panels to split water into hydrogen and oxygen and store both gases in tanks to be fed into a fuel cell to generate power (and perhaps heat) when the Sun drops below the horizon. Solar energy plus energy storage in the form of hydrogen and oxygen would equal an off-grid, personalized energy system.

Daniel Nocera, Ph.D. in discussing his work on solar hydrogen systems at Sun Catalytix, and his day job at the Massachusetts Institute of Technology, said at the 240th National Meeting of the American Chemical Society, "Our goal is to make each home its own power station. We're working toward development of 'personalized' energy units that can be manufactured, distributed and installed inexpensively. There certainly are major obstacles to be overcome — existing fuel cells and solar cells must be improved, for instance. Nevertheless, one can envision villages in India and Africa not long from now purchasing an affordable basic system."

A new catalyst could help speed development of inexpensive home-brewed solar energy systems for powering homes and plug-in cars during the day (left) and for producing electricity from a fuel cell at night (right).
Credit: Patrick Gillooly/MIT

With stored pure oxygen in tanks being used to feed the fuel cell, the power plant is bound to be more efficient than a typical hydrogen fuel cell which would use oxygen from the surrounding air to combine with hydrogen to generate electricity. Air, after all, is only about 21 percent oxygen. With 100 percent oxygen a fuel cell should work very well. Nocera’s work is to improve the oxygen generation capabilities of electrolyzers which split water. His low-cost catalysts wouldn’t require expensive platinum and would be able to boost oxygen production by 200 times. That’s a lot of oxygen.

Still, as much as solar-hydrogen-oxygen power systems seem appealing they would have to be made safe. Storing oxygen is dangerous business. Pure oxygen in itself doesn’t burn, and is not considered a flammable gas. Oxygen, however, does support – with great gusto – the burning of other substances. It’s the oxygen component in air that makes things combust or oxidize. Oxygen stored in tanks must always be treated with caution. Pure oxygen and hydrogen are fuels of rocket engines, by the way.

If the Nocera/Sun Catalytix catalyst works well and gas storage can be made safe, then this energy storage could be a competitor to batteries, provided hydrogen fuel cells, too, come down in cost. Using pure oxygen instead of air should allow the fuel cell stack – the core of a fuel cell – to be smaller thus decrease its cost.

Links

Sun Catalytix
http://www.suncatalytix.com

American Chemical Society
http://www.acs.org

Solar Electrical Power

Solar electrical power works by the conversion of light into other forms of energy. When you think of solar power the first thing that comes to mind is probably solar panels being used to generate electricity. This is known as photovoltaics. However, solar power is used for a lot more than just generating electricity.
Solar power has been used throughout human history for a variety of things:
* Heat engines: Concentrating light to generate heat to drive an engine.
* Space heating: Converting light to heat and trapping it inside buildings.
* Water distillation: Purification of water using evaporation.
* Water heating: Converting light to heat for warming water.
* Photovoltaics: Conversion of light to electricity for a variety of uses.

We’ll be focusing on how photvoltaics work here as I imagine that’s what you’re most interested in. More specifically our focus will be photovoltatic panels. There are in fact multiple types of photovoltaic energy sources though. So, what is a photovoltaic solar cell (PV cell) and how does it convert light to electricity? Quite simply they rely on the photoelectric effect. This is a quantum electronic phenomenon where electrons are emitted from matter after electromagnetic radiation is absorbed. Light is a form of electromagnetic radiation.

Light hits the solar panel and is absorbed by a semiconducting material like silicon. Some of the light is reflected back and lost but a special layer designed to reflect light back at the cell recovers some. Electrons (negative charged) come loose from their atoms (photoelectric effect) allowing them to flow through the material.
Solar panels have a special composition that only allows these electrons to move in a single direction. Now that this negatively charged electron has come loose in its place is a positive charged “electron hole” which flows in the opposite direction. The electron and “electron hole” move in their respective directions until reaching metal plates which are connected. This action creates direct current electricity.
The amount of knowledge that goes into understanding all the details of how solar power works could fill a book and many books exist that cover them more extensively. Check out the environmental impact of solar power as well. However, the above information covers all the basics of know about how photovolatic panels work. If you want to learn more about how solar panels work wikipedia has an excellent detailed explaination that goes very far into the science of each individual part.
I hope you’ve found my explaination helpful and have learned something here today. If you’re interested in other forms of photovoltaic energy you should look up concentrating photovoltaics (CPV) or fresnel lens sterling engines.