Wednesday, March 16, 2011

Fukushima and us

The continuing nuclear disaster unfolding in northern Japan makes our efforts to reduce our dependence on the electrical grid a little more urgent. In a general sense, it's important for us to limit our use of utility-generated electricity because of the numerous ways this energy source damages the environment and public health. But in a more direct way, our efforts will help prevent the construction of two new nuclear reactors in South Florida. More on that in a minute.

But first, the most important thing we're doing is not our photovoltaics. It's conservation. Every watt saved is a watt generated, or at least obviates the need to generate that watt.
And it doesn't take NASA-esque technology to conserve energy. Our highest return on investment will come from orienting the house so that our windows allow in lots of natural light (limiting the need for artificial light) but keep out the heat that comes with direct sunlight. It isn't difficult to fill the house with natural light while excluding the heat of the sun. Our next best investment is insulation, which, along with the careful use of sealants, will keep the house's temperature and humidity stable and comfortable regardless of the weather outside. These simple techniques are universally applicable and ought to be universally adopted.

There is some high tech in the house, too. Our air conditioning system is very efficient (SEER rating of at least 22), and we'll use LED lights in the rooms that get the heaviest use. The most prominent technology will be the photovoltaic panels on the roof, which are rated at just under 5kW and should produce more than half the electricity used by the house. We'll also have a solar hot water heater that will take the second hungriest appliance off the grid. Between conservation and generation, this house will use about one quarter of the utility-generated energy of a conventional house built to meet existing energy-use codes.

The common criticism of photovoltaics is that they only generate electricity during daylight hours. So how will this help prevent the construction of two new reactors in South Florida? By avoiding any increase in peak hour loads.

Utilities base their decisions on building new generation plants according to the peak use of electricity in a region, which is generally in the afternoon, when people are at work and the midday heat drives the need for lots of air conditioning. At night, when all those xerox machines and elevators and televisions and a/c units are lying dormant, much of the utility's generating capacity lies fallow. Our photovoltaic and solar hot water panels are going to produce energy at the time of peak use, which means we won't contribute to any growth in peak-time usage. Since we'll only add to the utility's load during off-peak hours, when there is extra capacity in the system, there'll be no need to expand local generating capacity. At least not from our family.

Photovoltaics won't - by themselves - replace utility-generated electricity, but they can eliminate the need for new plants like the two new nuclear reactors Florida Power and Light wants to build at Turkey Point. The reactors at Turkey Point are 25 miles from our house, and sit right at the point where Hurricane Andrew made landfall in 1992. Our 5kW rooftop array is more than an attempt to reduce our environmental footprint - it is a step toward preventing a disaster like Fukushima in our backyard.

1 comment:

  1. comment by Albert Harum-Alvarez:

    Great blog!

    Peak use is indeed when the sun shines, except for the HIGHEST ever peaks which occurred last winter one COLD morning. That's why we think thermal mass is so critical here in South Florida. It works both summer and winter, day and night, and costs only for the solid concrete that also strengthens our house against hurricanes.

    Our house's FPL bill last month was $38 for a family of five living comfortably with a pool—and that was after my dear son left the A/C on four four days with the windows open! No 5k solar PV array yet. But when we add it, our bill should stay below zero much of the year.

    FPL helped with our project, and when we asked them why they were helping with a project that would LOSE them money on our bill, they said, and I quote: "If everyone built like this, we'd never need to build another power plant."

    Here are some links on the house:

    There's a tour this Saturday at 4. Email for more info!