There was an article in the paper (The Ottawa Citizen) by a well know local contractor (Mike Holmes) about zero net energy homes. He described how to build the homes to take advantage of passive solar heating, how to make the homes air tight, how to exchange air without loosing heat and various other construction tips. The best part of the piece however was very light in content and had to do with power generation. He briefly mentioned solar and wind power but that was about it.
The first step in living off grid is to calculate how much power you are going to need. Having a clothes dryer for an example is probably a non-starter. Toasters can use as much as 1500 watts to make two toast. Here is a list of appliances with typical power requirements.
Power is current x voltage and is measured in watts. (P = I x V).
Typical power consumption of Various Appliances
Here are some examples of the range of nameplate power consumptions for various household appliances:
- Aquarium = 50–1210 Watts
- Clock radio = 10
- Coffee maker = 900–1200
- Clothes washer = 350–500
- Clothes dryer = 1800–5000
- Dishwasher = 1200–2400 (using the drying feature greatly increases energy consumption)
- Dehumidifier = 785
- Electric blanket (Single/Double) = 60 / 100
- Fans
Ceiling = 65–175
Window = 55–250
Furnace = 750
Whole house = 240–750 - Hair dryer = 1200–1875
- Heater (portable) = 750–1500
- Clothes iron = 1000–1800
- Microwave oven = 750–1100
- Personal computer
CPU – awake / asleep = 120 / 30 or less
Monitor – awake / asleep = 150 / 30 or less
Laptop = 50 - Radio (stereo) = 70–400
- Refrigerator (frost-free, 16 cubic feet) = 725
- Televisions (color)
- 19″ = 65–110
- 27″ = 113
- 36″ = 133
- 53″ – 61″ Projection = 170
- Flat screen = 120
- Toaster = 800–1400
- Toaster oven = 1225
- VCR/DVD = 17–21 / 20–25
- Vacuum cleaner = 1000–1440
- Water heater (40 gallon) = 4500–5500
- Water pump (deep well) = 250–1100
- Water bed (with heater, no cover) = 120–380
So what kind of systems can deliver the power we need to run our homes without hooking up to the local power authority?
As a general rule of thumb, eight square meters of roof space will produce one kilowatt and a cost of $10,000 installed. To get more power you just install more panels. All calculations are linear.
So what do you do if the sun doesn’t shine (That never happens in Canada [grin]). If the solar panels are not producing power, then you have to have backup batteries or another source like wind power. The problem with wind power is that some people find the systems ugly. So a challenge for the architects out there… Design a house with a build in flow through wind power generation system. All we have to do is get the wind to always blow in the same direction.
There are lots of ways to store power. Here are some of the more “out there” ideas.
- http://vyconenergy.com (Flywheel systems for storing energy)
- http://afstrinity.com/ (Currently working on powering cars)
- Compressed air
- Water tower
- Falling weight
- Compressed spring
- Fuel Cells