If you’re lucky enough to have water moving through your property, you have more than a constant source of relaxing nature sounds. You have a potential candidate for a micro-hydro power system.
A micro-hydro power system is an independent power generator with a capacity less than 100 kW. Considering that a 10 kW system can power a large home, your stream or creek could be more than capable of meeting your home energy needs with the right system.
How do Micro-Hydro Systems Work?
Much like wind energy is harnessed by a turbine to create rotational energy, flowing water is directed through a turbine hooked up to a generator that turns the rotational energy created by the turbine into usable electricity.
While full-scale hydropower stations operate by damming rivers and creating reservoirs, micro-hydro systems are “run of river,” which means they merely divert a portion of the water’s actual flow.
Systems will typically work more or less as follows: a diversion component takes in water from the water source and a pipeline, canal, channel or penstock (a pipeline that’s pressurized) delivers the water to the generating station. Once there, water is directed at a turbine or pump, which creates mechanical power. A generator turns that power into electricity. The water then moves through a tailrace and back to the water source, while the electricity is moved along transmission wires to the home.
Additional components are likely to include a filter or screen to keep out debris, load controllers to manage the electric power and an inverter to turn the DC current that will be generated to AC. Off-grid systems typically add a battery bank.
What Are the Basic Site Requirements?
The basic requirements that make a site a good candidate for a micro-hydro power system are a stable moving water supply with sufficient head and flow.
Flow is simply the volume of water that passes through your site (calculated in gallons per minute, liters per second or in cubic meters per second, depending on what country you’re in). Head is the elevation difference between the point where water will enter the system to the point where the turbine will be located (measured in feet or meters).
Land and water surveys will provide you with basic information about your property and the water on it. Energy.gov walks you through several methods for measuring head and flow here. They state that a site with less than 10 feet (3 meters) of difference in elevation would be considered “low head,” while a change of 2 feet (0.6 m) or less would make the site unsuitable for generating hydro power. Renewables First suggests a bare minimum of 1.9 m3/s of flow and a 2m head.
Beyond those minimums, the more stable your on-site water resources are (i.e. not likely to dry up in summer as well as freeze over in winter), the more power you’ll be able to generate. Likewise, the greater the flow and the head of your site, the more power you’ll produce.
What Are the Pros and Cons?
One big pro is that since micro-hydro systems don’t require dams or reservoirs, their impact on local waterways is minimal.
These systems tend to be reliable and long-lasting, with low maintenance and operating costs. Natural Resources Canada (NRC) states that hydropower “can produce many times more power and energy than several other sources for the same capital investment,” so value is a plus.
Day to day, micro-hydro power is also a more stable source of energy than either solar panels or wind turbines. Water will run regardless of time of day and has less short-term regard for weather than either solar or wind.
That said, power will vary seasonally, rather than day to day. Since a micro-hydro power system could be inefficient or inoperable for longer periods of time (if, for example, you have a small stream that’s impacted by a deep freeze or prolonged dry spell), storing energy in batteries becomes less feasible.
Another down side is that every site is highly unique. Unlike solar panel installation, which is more standardized and often similar from home to home, micro-hydro power systems will require a lot of individual configuring for optimal performance, whether you DIY this project or hire a professional.
On-Grid or Off-Grid?
This is a big question for people installing their own green energy systems., and there are pros and cons to each position.
In remote locations, it will probably be more cost-effective to install an off-grid system than to bring the closest power grid to you (if that’s even a possibility).
Micro-hydro systems can be grid-tied, though, which allows system owners to feed energy back to their utility for some kind of credit at times when there’s a surplus of energy. Many utility providers will then use that credit to offset the owner’s electric bills at times when the owner needs to draw power from the grid. Check with local, regional and federal regulators to find out what kinds of incentives and programs are available for tying your system in.
How Do I Get Started?
It’s generally suggested that you study your site and gather water data for a solid year. That will let you account for seasonal variations in flow in your planning.
If micro-hydro power still sounds like a viable option to you, your next step will be to contact your local permit department. You’ll need approval for land and water-use and are likely to need a building permit, as well as approval from conservation authorities, depending on your location and your project.
You’ll then need to determine if you want to DIY this or call in a professional. DIYing your own micro-hydro system will require some extra research on your part, given the many site and design considerations and the components you’ll need.
Having a system installed will put the onus of finding the correct size and type of turbine and generator, as well as the work of optimizing the energy system, in someone else’s hands. That, of course, will come at a cost.
Whatever route you go, be sure to gather all the information you can. Also be sure to minimize site disturbance during installation to keep your aquatic ecosystem healthy and happy.