Micro-Hydro systems are a great way to produce large quantities of electricity from moving water. If the right conditions exist significantly more kilowatt-hours can be made over solar, wind and other forms of small-scale renewable energy systems. This is because solar and wind power is intermittent. The sun shines only a few hours a day and wind patterns change constantly. For the most part, running water continues to run regardless of the weather outside or time of day.
As a renewable energy system integrator I get many calls and questions about micro-hydro systems, how they work and what kinds of water resources are needed to turn moving water into electricity. Many people are surprised to hear that in order to generate electricity from water, the conditions must be favorable and not every site has this potential. The intention of this article is to clear up many of the myths around micro-hydro energy systems and shed some light on how they work and weather or not this kind of system is right for your needs.
Myth One: Any water source can generate power.
It is not true that any water source can be used to generate power. The water must be moving and falling to generate power. There must be enough volume and elevation drop to create the pressure needed to spin a turbine and generate power. The most productive sites have a combination of water volume and fall. Sites can also have high flow volumes with little fall or low water volume and high rates of fall. Regardless of the site, it is necessary to have both volume and fall to create power.
This high altitude stream is fed with snowmelt so the volume fluctuates throughout the year. The fall is steady as it goes straight down the side of a mountain, thus making it a suitable micro-hydro site.
Myth Two: Micro-hydro systems only work in places with consistent water flow.
When looking at a site we first need to calculate the flow and fall of the water to see its potential for power production. Fall remains consistent but fluctuations in flow are common throughout the year. Snowmelt, rain and removal of water upstream are factors that can influence your ability to generate power. With less water volume comes less power and vise versa. When designing a micro-hydro system it is important to know how the water flow varies through out the year. This is especially important when the system in question is charging batteries for an off grid application. If the water dries up so does your power, so take notice of the flow during different seasons. Systems can be designed to handle varied flow rates but as the water flow lessens (typically in winter) so does the power production.
Myth Three: Creating artificial fall by pumping water up a hill will be enough to make power.
This comment comes up a lot and the answer is yes, and no. Sure, you can pump enough water up a tall enough hill to allow it to fall and create power. But you most certainly are using more power pumping that water up the hill than what the micro-hydro system will provide for you in return. For example, it could take 1000 watts of power to pump enough water up a tall enough hill only to provide you with 400 watts at the turbine in return for that effort. So yes, it can be done but it doesn’t make sense to do it. Creating electricity free ways to gain elevation in order to increase fall have some advantages but using electric pumps is not the way to do it. If your site doesn’t have the fall necessary to produce power it is simply not an acceptable site for micro-hydro electric production.
Myth Four: Micro-hydro systems are only used for charging batteries.
Micro-hydro electric systems were typically designed to charge batteries in off the grid energy systems. Because they produce power 24/7 relatively small micro-hydro systems are capable of charging large battery banks. This is especially true when compared to the charging capability of solar or wind power systems, which only give full power at specific times of the day. Because of the great power potential from micro-hydro energy, systems today can be designed to both charge batteries for off grid use or simply sell power back to the grid just like a grid tied solar system. Micro-hydro electric systems are very adaptable and can be easily integrated into a variety of other renewable energy systems both on and off the grid.
Myth Five: Micro-hydro systems cost less than other renewable energy systems.
Micro-hydro systems are very site dependent and how they are designed and installed varies from one site to another. Most of these sites are in rugged areas and construction in remote and rugged environments generally costs more than construction in cities. It is also quite common to bury the water delivery line and doing so in certain areas like the middle of the Colorado mountains at 12000+ feet in elevation proves very costly; much more so than digging a trench in suburbia. Typically the installation portion of a micro-hydro project is more costly than the equipment portion. This is not the case with wind and solar projects where the equipment costs exceeds the installation. As said earlier, each site is different and there are micro-hydro sites where the installation is a breeze and power can be made for very little cost. A professional with experience working with micro-hydro electric systems can best determine the potential of your site with experience working with micro-hydro electric systems.