With the consequences of global warming piling up daily on our TV screens, and in our back yards, it’s not surprising many of us are getting the itch to ‘do something about it’. After all, waiting on the political class to pull their collective fingers out, and take a lead on environmental responsibility, has hardly been a stunning success. If we’re going to get any traction on avoiding the worst excesses of climate change, we need action, and fast. So the urge to start plastering the roof with solar cells, and to garland the garden with wind turbines, is understandable. Understandable- but is it really the best way to move things forward – will the bang, in terms of carbon emissions reduced, be worth the bucks you spend?
When it comes to wind turbines, it’s a very valid question. That’s because, to make a measurable dent in your carbon footprint, wind turbines are pretty demanding of your home and its surrounding landscape. Wind may be plentiful, but clean, readily harness-able wind needs good location, plenty of space and a nice clear run-up for the breeze. So for those seriously considering wind power, foremost because they want to make a serious impact, assessing the suitability of your home and locale is a big initial hurdle.
Get a handle on your total energy usage. This is quite simple- just look at the kilowatt hours (kWh) on your electricity bill for the last four quarters, and add them up, for an annual electricity consumption figure. Now, you need to decide on what sort of a proportion of that bill you would like your wind turbine to supply. Obviously 100% is what we’d all ideally like. But that is unlikely for most homes – 25% to 50% is more realistic, and this still feels like sizable reduction in emissions.
Now things get a little more tricky- in order to be in with a chance of generating substantial electricity, your turbine needs to be hit by winds averaging at least 9-10 mph (or 4.0 to 4.5 m/s) – at the height you expect your turbine to be lofted to. How can you find this out? Well ideally you would monitor the wind for a likely site, for a year, and crunch the numbers to produce an average. Wind monitoring devices, known as anemometers, have long been available- but you’ll also need something to collect the data, a totalizer.
However, if you haven’t got that kind of patience, a shortcut is to check out the wind maps for your area. These are widely available, both from commercial and state sources, and you can quickly see if you meet the minimum 9-10 mph criteria. But bear in mind that these are usually classed by height- and typically don’t go lower than 50m (150 feet). If your turbine is likely to be placed lower than that, you’ll need to adjust for reduced height – going down to 10m (30 feet) can knock as much as 5mph off of the average wind speed That is why minimum heights of 25-35m (80-120 feet) are often recommended for the turbine tower.
But, in order to achieve even that theoretical average, your immediate location will need to be pretty uncluttered. Most wind turbine installers will suggest an acre of land around your property, and for it to be at least 6m (20 feet) higher than any trees or buildings, located within 75m (250 feet). Now you need to consider the size of wind turbine to purchase. They are commonly rated by the generator power output, which will be in kWh; but this measure is misleading.
It turns out that it is the combination of rotor length, generator and average wind speed that really matters, for determining the energy you get. So reputable turbine manufacturers use a table for determining the Annual Energy Output, for which you plug in the area swept by the rotor, and the average wind speed. This number will tell you whether your proposed turbine will really heft into your annual energy use, and so slash your emissions.
If your potential site passes all of those hurdles, and your local zoning regulations will allow such a structure, then you may be onto something. However, given the fact that such a purchase is not an inconsiderable amount of money, it is essential to get a professional in. Don’t rely on your ‘back of the envelope’ calculations- get a proper site assessment. Now if that all sound like a lot of factors to take into consideration, don’t let that put you off. These are all hurdles for those attempting a serious renewable energy solution for their homes.
Most homes are also suitable for smaller solutions, such as efficient micro-turbines, installed. With these, however, you need to realize that many smaller roof-mounted turbines will have supply an intermittent 10%, or less, of your total energy consumption. But, if these smaller installations are done as part of a package of other energy saving changes, then a cheaper, or DIY wind turbine kit can be an important part of making a difference. If nothing else, at least you’ll know that not all the wind whistling past your house is going to waste- and you’ll have a visible sign that you are not one of those sitting on their hands, while the planet burns.
This article is a guest post from Adana Lima, a stay at home mom with 3 cute kids (Jamie, Pablo, Guerrero) who writes on the topic of adjustable dumbbells