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  • Lily Dittschlag & Dennis Dittschlag

RENEWABLES: IS WIND POWER A VIABLE OPTION FOR RESIDENTIAL BUILDINGS?


Passive House Toronto

When looking into options for building a sustainable home, you will inevitably come across renewable energy. It's not a secret that there are different ways to power a home outside of the standard utility power grid, or at least supplement the supply with a renewable power source to use less grid power.


We have previously covered rooftop solar systems and geothermal heat pumps, but today let's talk about wind power.


Wind power appears to be a bit of an untenable subject because most people think of wind energy in terms of large-scale industrial turbines shown in the picture above. Others may have a more romantic image in their mind like this...


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But really, the question is: Can you harness wind energy for a residential property like a family home?

The short answer is yes!


Small wind turbines have been around forever and are commonly used around North America, especially on farmlands and off-the-grid properties. Unfortunately, there are many variables and constraints to be taken into account that will make this technology prohibitive in an urban environment, while it can make sense in a rural setting. Let's see what factors play a role for or against a wind turbine setup.



What are the critical factors?


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Here is a list of the main deciding factors that will allow you to determine if a wind turbine is feasible for your property:

  • Your site has enough wind

  • You have enough space around the turbine location

  • Your local zoning codes, by-laws, or other applicable regulations allow wind turbines or taller towers

  • You know your electricity demand and how much of it you want to compensate with wind power

  • It makes sense for you economically, meaning a larger initial investment will be amortized by smaller savings over time.


How much wind do you have?


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The wind available on your property is a crucial figure that will not just determine if wind power makes sense for you overall, but also what size of a turbine is required to meet your energy demands.


The wind is very subjective. Many people will say that there is decent wind in their area that blows constantly with occasional increases depending on season and weather. To properly spin a wind turbine and generate enough power, the wind needed regularly is actually quite significant. This cannot be left up to feel or personal impression but must be validated with actual data.


Ideally, a wind assessment is done on your property that will let you know exactly how good the wind source is. In absence of such an assessment, you can turn to historic weather data and measurements for your area. Just for the fun of it and to provide a reference, here is some data for our area (we live in the neighborhood of Mimico in South Etobicoke as part of Toronto) taken from weatherspark.com:


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The wind speed varies significantly between the colder half of the year and the warmer months over the summer, with an average wind speed around 18km/h measured at 10m above the ground. This is about 5m/s and generally classified as a "gentle breeze" (just goes to show how personal perception and reality can differ).


Logically, the more wind you have available, the more electricity you can produce. Many turbines have an entry-level or "kick in" speed at which they start to operate and generate power. Even the lowest average available wind speed should be above this entry-level.



Do you have space?


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Available space around the wind turbine is another big topic to consider. Any objects around the turbine can cause turbulence that impacts the efficiency of the turbine's output. Things like houses, trees, or features in the landscape can have a profound effect.


For a sizeable turbine that would generate a reasonable output for a residential home, it would require the turbine to be 400+ feet away from the home (or any other obstacles) for best performance, see illustration below:

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Source: windexchange.energy.gov

Additionally, the turbine needs to be at a significant height, for two good reasons:

  • The higher you are, the stronger the wind is, by exponential factors (thereby improving the efficiency of the turbine)

  • The average North American two-storey family home is about 18-20 feet tall. As per the illustration above and industry recommendation, this generally puts the tower height to 80-120 feet (now that's tall!).

Whether it's a free-standing tower or a wire-supported guy tower, the other factor to consider here is the installation and maintenance, meaning you need enough space to safely take the tower and turbine down and bring in the equipment to do so.


Theoretically, you could still put a turbine closer to an obstacle or even on the top of your house, but this will dramatically impact the system's performance. Installing a turbine on a house will also require the house to be engineered to carry the load and absorb the vibrations of a moving turbine.


So, space requirements are not feasible in an urban setting.



Is it allowed to install a turbine on your property?


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Your local zoning regulations, building codes, by-laws, or other applicable regulations will determine if it is allowed to install and operate wind turbines in your area, and/or if taller towers are permitted.


To get a clear answer on this topic is actually not so easy, mostly because a wind turbine is not a common situation that is regulated explicitly. Consulting your local city, municipal or provincial authorities is a must.


Funny enough, the Province of Ontario does not require approval for wind turbine systems at or under 3kW capacity. These are obviously smaller systems, but a curious fact nonetheless.


On top of the permits required to build a wind energy system, anything that generates electricity will need an inspection by the Electrical Safety Authority (ESA). And if the system is connected to your house and the utility grid, which it most likely is, you will also need to make arrangements with the local power utility.


This could be a minefield, so inform yourself thoroughly. There is some information available online and our province has the Ontario Ministry of Energy's Renewable Energy Facilitation Office (REFO) at 1-877-440-7336 (REFO) or e-mail: REFO@ontario.ca.



How much power do you want to generate?


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To satisfy the demands of an average North American family household in a detached home (about 11,000kWh per year), the wind turbine needs to have a capacity of 5kW and more. Typical residential turbines fall in a range between 5 and 15kW.


The sizing of the system will first depend on your own needs, meaning your energy budget. Another question to face is whether you want your entire energy demand to be satisfied with wind energy, or just a portion of it, or possibly more than your own demand.


Once the demand side is clear, the other two critical factors we discussed above, wind source and tower height, will determine the sizing of the final system. Depending on your circumstances, you could of course have multiple turbines as well, but for residential applications that is not the norm given the land requirements.



Does it make sense economically?


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Costs for wind turbine systems vary significantly, so it is hard to put an estimate on an average residential system. However, as with any investment into your home, you need to consider the total cost of ownership. This needs to include:

  • Upfront costs of planning, engineering, permitting, and inspections;

  • Implementation costs of purchase and installation, including the civil works and any equipment needed to connect the turbine to the electrical system of your house and a potential energy storage solution like batteries;

  • Annual costs for maintenance, repair, and spare parts (considering also that some tasks may need to be performed by a qualified technician).

Outside of the costs to install and run a wind power system, the opposite side needs to be considered as well. How much money does this system save you over time? After how many years have the costs been fully amortized? When is the system actually making you money (by selling power back to the grid)?


And let's not forget that any homeowner needs to be comfortable with carrying and servicing the additional debt caused by the initial investment.


If the numbers work out in your favor, you are good to go ahead.



Advantages of a wind energy system


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A wind turbine can be a very cost-effective way to generate renewable energy at home, in particular when you have a strong wind source. It can save you money by offsetting a portion or all of your electricity needs.


The wind is a clean and indigenous renewable energy source. It doesn't matter whether it's day or night, summer or winter, the wind blows all the time and a turbine can generate power around the clock.


Many systems are pre-certified, have a good manufacturer's warranty, and are designed to last 20 to 25 years.


Wind energy can be combined with other renewable energy sources, e.g. solar, to make up a whole system. This will depend on your overall concept and the site conditions, but it's a common approach to combine multiple power sources for optimal results.



Disadvantages of a wind energy system


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Wind turbines have moving parts and will require maintenance, oftentimes by qualified technicians.


You need to have a strong, consistent wind source or you will end up with a spinning toy in your yard that will not produce the desired power output.


A turbine will require lots of space. Many recommendations for residential systems refer to having at least one acre of land. This clearly eliminates a wind energy system from adoption in the urban environment.


Once you have committed to a turbine, you have also committed to the esthetics. While there are different turbine types with horizontal axis (the most common type is the propeller look with 3 blades) or vertical axis (helix or eggbeater designs), a turbine on a tower or a building may be considered as visual pollution.


Wind turbines generate some noise, but smaller, residential systems are actually at similar levels to your dishwasher or washing machine. A possible impact on the other hand could be on the local wildlife, especially birds.



Conclusion


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While wind power is significant enough to compensate the energy demand of a family, it is unfortunately not feasible in the city or suburb. Wind energy makes more sense in rural environments with a strong wind source and remote off-the-grid properties.


The most practical application for wind energy is on the utility-scale, at industrial production levels, which can also be done at wind farms offshore. Of course, this comes with its own challenges and environmental considerations (i.e. how does an offshore turbine get recycled after 25 years at sea?), but the technology has seen tremendous growth globally.


The story of renewable energy on a large scale and in-home applications and its integration into the power grid is quite fascinating to us. While wind power is not in our immediate future, sustainability --- or at least environmental responsibility --- will be.


Finally, here are some interesting and helpful links we have found as part of our research into residential wind power:


https://www.energy.gov/energysaver/installing-and-maintaining-small-wind-electric-system#:~:text=Small%20wind%20turbines%20used%20in,kilowatt%2Dhours%20per%20month).


http://www.omafra.gov.on.ca/english/engineer/facts/18-005.htm


https://windexchange.energy.gov/small-wind-guidebook#certified




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