Friday, February 4, 2011

Latest From : CleanTechnica

Latest From : CleanTechnica


Who Else Wants a Great Solar Water Heating System?

Posted: 04 Feb 2011 04:00 AM PST

Solar hot water systems can save a lot of money and decrease a family’s environmental footprint. Deciding to install solar panels, however, is a huge undertaking. The first step of installing a solar hot water system is to evaluate one’s home’s solar resources. Is the home exposed to enough sun that installing a heater would be economical? Will daily heating needs be met by the amount of sun the panels will utilize? This can be found by either using the evaluation tools at energysavers.gov or by contacting your local solar contractor.

If the site receives enough sun to continue with the project, it must next be determined what kind of system is appropriate for the circumstances. If the system is to be installed in a warmer environment where the temperatures are rarely below freezing, direct circulation systems are best. This system pumps water through the solar collectors on the roof directly through the home, slightly increasing the efficiency but also increasing the possibility of frozen water and burst pipes. Alternatively, indirect circulation systems pump heat-transfer liquid through the solar collectors and then transfer heat into pipes in the home. This is better for colder environments where the water in a direct circulation system would freeze.

Once the type of system is determined, the rest of the parts, such as the heater and the solar collectors, must be selected. Different types of systems, such as active and passive heating systems, are better for different homes. The most important metric to keep track of when choosing parts are the system’s solar energy factor (SEF) and solar fraction (SF) The SEF is the ratio of the energy delivered by the system to the energy required to power the system. This ranges from 1.0-11, with higher numbers being ideal.

The SF is the decimal percentage of heat delivered directly by the solar panels. A rating of 0.75, for example, means that 75% of all heat in the home is delivered through the solar panels. The remaining 25% is being heated by a backup hot water heater. Other things to consider are the size of your home, total overall cost, and ease of installation.

Finally, one must consult with a solar contractor in order to obtain the parts for the home. Although it is possible to install the system individually, obtaining professional installation ensures an easy installation and lessens the probability of injury. Overall, however, the price of the professional installation will be offset by the savings obtained by using this environmentally friendly hot water system.

Shannon Marie Combs contributes articles for the Residential Solar Panels blog, her personal hobby blog centered on ideas to aid home owners find solar installers and learn how to to conserve energy with solar power.

This post was syndicated by Nathan Brown. He is the green building job recruiter for Dancing Rabbit Ecovillage, as well as a provider of going green ads, and info on how to build your own solar panels.


Secessionist Grid Hurts Texas as Day After Tomorrow Freeze Causes Blackouts

Posted: 03 Feb 2011 03:51 PM PST


Go-it-alone Lone Star state Texas might be having second thoughts about keeping its grid separate from the US grid this week.

Sub-zero weather is hitting states far from the Arctic that are not prepared for it, like Oklahoma and New Mexico. Some adapt better than others. People in Atlanta learn to shovel snow, but Texas has had to close power plants because it was unprepared for bursting water mains.

Texas is having rolling blackouts because the state had no prevention plan covering frozen water in the pipes serving fossil-fueled power plants. And it is not easy to get emergency electrons supplied from other states. Texas has almost completely seceded from the national grid.

The frigid weather across the state caused up to 50 fossil-fired power plants to go out of service unexpectedly Wednesday morning, knocking out some 7 GW of generating capacity among 50 fossil-fired power plants — more than 12 percent of the day’s projected power demand. (Wind turbines were unaffected, and kept producing the planned 3.5 to 4 GW of power contracted for, about 7% of the state needs).

Usually winter is a good time for maintenance and 12 GW was offline – at what is normally a low peak time with no danger of air conditioners running – for repairs. But with the cold weather, more electric heaters were running, and gas was also impacted by the higher than average need for heating.

After a day of rain, followed by freezing temperatures, both coal and gas-fired plants had to be shut down as their water pipes froze. Gas-fired pipelines face an additional danger in freezing temperatures that are not planned for. During extreme cold, a small amount of water mixed in could freeze. Most of the outages are from power plants in the northern part of the state where temperatures have been below 32 degrees for several days straight and in some parts of Texas, the wind chill is 32 below zero.

Rolling blackouts, beginning at 5.30 Wednesday, like the ones that Enron inflicted on California in 2001 in order to replace its Democratic Governor with a Republican, are making Texans mad, and reviving Enron conspiracy theories. (Enron didn’t have the intended effect, because Schwarzenegger did not turn out to be the Bush-like malleable fool that his backers expected).

But the cause is possibly something we are all to blame for, not some clever conspiracy. Climates are changing. Freakish weather, long a predicted effect of the overall increase in temperature globally, is starting to wreak havoc worldwide.

As climate change has heated the Arctic, now there are freakishly colder winters, with heavier snowstorms in Europe and the US. Some scientists are attributing the change to the weakening of the polar vortex as Arctic temperatures have heated up. Freezing temperatures that used to stay circling the North Pole in the jet stream now “jump the fence” that used to keep them penned up.

NOAA climate scientist James Overland suggests that the warmer Arctic ocean is heating the air above it enough to making it less dense, equalizing the air pressure, cutting down the barrier so that it is now easier for extreme winter temperatures to head South.

Susan Kraemer@Twitter


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