Showing posts with label solar power. Show all posts
Showing posts with label solar power. Show all posts

For Marilynne: Carbon Savings

>> Monday, September 14, 2009


Marilynne asked: Solar. Our inverter for our solar panels says we have not contributed 600 pounds of carbon to the environment in the few weeks we've had it. Where does this carbon come from? Power plants or something else?

Presumably, your inverter has calculated the power you've used via the solar panels and there is a standard value assigned as the amount of carbon burned used per kilowatt hour. For instance, my power company (because I use Green Mountain Energy which is 100% renewable energy) says I've saved 855 pounds of carbon last month. Here's the source for their value: U.S.
Environmental Protection Agency, Energy Information Administration, EGRID 2004 database, Texas State Carbon Dioxide Emission Rate of 1.420 lbs of CO2 /kWh.

In theory, this represents how much carbon dioxide would be produced if that same energy were produced by fossil fuels. Chance are your own are is using a similar value in keeping with local norms. I'm not sure if all fossil fuels produce the same amount of carbon per kW, but it's a reasonable estimate.

So this represents the amount of carbon your utility company is not having to produce to provide the power you used. Congratulations!

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For Jeff King: Going Solar

>> Friday, September 11, 2009


Jeff King asked: Are solar panels worth the investment to run electricity for your house?

It's a simple question with not quite so simple answer. I'm a huge advocate for green technologies and certainly think solar power has tremendous promise. It is versatile, reliable (as has been demonstrated by a substantial number of key spacecraft out there), and, after the original investment, free.

But, at the current time, they're expensive. Prices are currently going down and efficiency is going up for photovoltaic cells. That's good, but it means that an investment today won't buy you as much as it will tomorrow. Unfortunately, if no one invests today, of course, prices will stay high so there's some gambling. In order to get the most from a P-V (photovoltaic) system, you also need to change how your house uses power and perhaps put in battery backups. However, there are some tremendous tax advantages that can recoup a substantial portion of the investment.

So, are they or aren't they a good idea today?

Well, there are a number of factors. First, where do you live? Do you live in a climate with a great deal of sun (i.e. rarely overcast, long days, etc)? Higher altitudes can have an advantage as well, though not by much. If you live somewhere where sun isn't a big part of your days, you won't be getting your money's worth out of your solar panels. Do note, however, that Europe (which is largely further north than we are in the US, has managed to get a lot of mileage from solar power).

How long do you think you'll live in your house? If you're there for the duration, an investment that may not really pay off for a decade may still be well worth it. But, if you expect you might be moving in three, five years, it might not make as much sense.

How much space do you have to devote to panels? If you have a small footprint to work with (or one that spends time in shadow), P-V cells might not be the correct option at this particular time.

But, don't despair. Whether or not solar P-V panels are right for you at this time, you aren't necessarily out of options. There are solar water preheaters that can reduce the cost of heating water without necessarily requiring an entiry house switchover. Wind generators may be alternative if the solar panels aren't.

And, whatever you do for greening your house, something that always makes sense is reducing your energy footprint. If you live somewhere hot and sunny, solar screens, radiant heat barriers or ugrading aging AC units can have a drastic impact on your energy usage. Hot or cold climates, switch to low wattage bulbs (LED bulbs are already available, but compact fluorescents can make a big difference), get a programmable thermostat, and seal your house. Consider investing in higher efficiency windows and, when you replace appliances, always go for those that are most efficient. Knowing how to use your windows to the best effect in winter or summer can also go a long way toward a happy energy situation.

The sun is a wonderful thing and I have high hopes for it's effective use. Do your homework and compare it to your particular circumstances. Remember, every watt we don't use or we can generate through clean energy is to the good.

And keep up with advances, whatever you decide in the short term. The situation is radically changing and a bad deal today may be a good deal tomorrow.

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