Sunday, December 21, 2008

Still dependent on fossil fuels after all these years

We have an array of 22 solar photovoltaic (PV) modules on our roof here in New England that will probably end up providing more than 15 percent of our kilowatt hours in 2008 (an upcoming blog will inventory our 2008 energy use).

This is great production, don't get me wrong; we don't exactly live in sunny Vegas or Boulder. Yet as we sit here in two feet of new snow (pretty, mind you), it occurs to me that we are still not quite hopelessly dependent on fossil fuels.

solar modules we hardly knew ye

On days like this, our solar PV array, which often provides up to 100 percent of our daylight electricity, is completely knocked out. If one or two modules in a PV array are covered by snow, for instance, this usually disables the entire array until the snow melts off (or I roof rake it off, which is known to happen!).

Homeowners have an option, however, to place a free-standing solar array on their property, which can easily be shoveled off.

Consequently, our house is heated by two propane-burning Monitor and Rinnai heaters downstairs, a conventional heat pump (electricity) when the temperature needs to be raised upstairs, and a fireplace insert that I am sitting beside writing right now. None of the energy sources are renewable or really sustainable (except for the wood, which I speculate is responsibly rotated at the local farm where I buy it).

Although we buy "green energy" in Massachusetts, the typical electricity user in Massachusetts derives more than 80 percent of their energy, according to this site, from nuclear (28 percent), natural gas (33 percent), coal (12), and oil (10 percent).

Solar provides far less than one percent of the electricity in Massachusetts, which is why our 15+ percent is exemplary. However, if we depended on solar for a substantial chunk of our heating, say, to power our heat pump, we would freeze and our pipes would burst.

Thus, we are overly dependent on propane to heat the house. Propane is a byproduct of oil refining or natural gas processing, and is not a renewable fuel. When natural gas and oil inevitably peak and decline, so will propane. Although our small heaters do a very good job, their use is ultimately not sustainable.

Propane is expensive too; $3.15 per gallon on our last bill. A very cold winter month will result in the burning of 100 gallons of propane by our machines (we also use it for an oven). In addition, burning propane produces carbon dioxide, a greenhouse gas. Further, since our country is dangerously dependent on oil and natural-gas exporters, then propane is also a part of this problem.

Propane is also potentially hazardous, as it will blow up a house if released in quantity and ignited (we store ours in two tanks on the side of the house).

The point is that the northeast U.S. is a very long way from being able to substantively provide heat energy from renewables: solar, or wind for that matter (ground-source heat pumps are a different story, and the subject of a future post).

That doesn't mean, however, that the sun belt of the U.S., including Arizona, California, Colorado, Nevada, New Mexico, and Utah, could not generate substantial amounts of energy from solar thermal plants in their deserts.

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