I f you live near falling water, a small-scale hydro system may work well for home electricity production. With micro-hydro systems, power generation can range from 100 to 2,000 watts of electricity production from streams or small rivers, with minimal damming and water diversion. A dam serves as a way to create both a reservoir and a flow diversion. The diversion sends water to an inlet pipe at the top of a vertical drop, which is required to develop the necessary pressure to spin a water-powered generator. The reservoir also helps provide a relatively constant flow of clean water with no air pockets. You will need such a reservoir, but substantial dam construction is beyond the scope of a typical home power project and therefore is not covered here. Most rivers and streams flow all day long and year-round, making hydropower more consistent — and often more cost-effective — than solar or wind energy. Of course, seasonal flow variations, and freezing or drying of the water may be real issues in your situation. This chapter will help you to evaluate and understand the potential for hydroelectric power at your site.
Home Hydro I t is some w h at rare to find a location that meets all of the practical requirements to make harnessing water power worthwhile. You need access to enough moving and falling water that is reasonably close to a dwelling that can use the power (or to grid power for grid intertie), and you need to secure the required local, state, and federal permits and rights to access the water and harness its power. If such a site is yours, you have struck your own little oil well, and opportunity awaits! Large-scale, alternating current (AC) hydro systems are generally not practical for homeowners due to cost, complexity, regulations, and the volume of water needed to make the investment worthwhile. Micro-hydro systems don’t require much alteration of the stream and so have a minimal impact on waterways and ecosystems. The power generated by a micro-hydro system may be AC or direct current (DC) but will often be converted to DC so the energy can be stored in batteries. In fact, most micro-hydropower systems can be considered battery chargers. One significant advantage to energy storage is that the generator can be much smaller than your peak power demand, relying on batteries and a power inverter to manage and deliver any power surges required by the loads that exceed the output capability of the generator. The iconic image of an old-style water wheel is not the modern way of generating electricity that we’ll explore in this chapter. Water wheels collected water’s energy as it flowed through a river or over a relatively short dam at high flow rates, low pressures, and low speeds. The energy harvested was used for mechanical power, such as grinding grain. Today’s modern hydropower turbines require water to be delivered at high pressure through a nozzle that focuses a jet of water onto a fast-spinning wheel, or runner, which in turn spins an electric generator. The most common way to capture the water energy in micro-hydro systems is to divert part of the stream through a pipeline, or penstock, downhill to the power-generating turbine, which may be sheltered in a small shed or powerhouse along with the required controls. After the water has done its work, it flows back into the river, often through another pipeline, called a tailrace.
How Much Power Can You Make?
There must be enough energy in the water to justify installing a hydro energy system, so quantifying water resource is the first order of business. To estimate the available power of a stream requires the understanding of a couple of key performance factors: • How much water is flowing over a given period of time (flow) • How much pressure (head) can be delivered to the hydropower generator Head and flow will determine everything else about the design of your hydropower system, so you must capture these two parameters first — and with reasonable accuracy. Accuracy cannot be overemphasized: If you want to make the most of the time, money, and labor invested in your power system, you must take accurate measurements. Once you know how much potential energy is available in the water, you can begin to design the systems to collect, control, and store this energy. Those details include:
• Determining the type of turbine that best suits your site
• Working with manufacturers to tailor the turbine specifications to your site
• Sizing the generator capacity — usually a compromise between meeting your power needs, what the water can support, and cost
• Determining how much water must be diverted to support the generator
• Sizing and layout of penstock pipe and wiring
• Determining requirements of controls When you have some understanding of your water power site and requirements for harnessing that power, it’s time to contact a water turbine manufacturer to begin fine-tuning the design, based on the specific equipment you choose. Working with a manufacturer is important because there are many turbine variables that can be customized based on your specific site. Manufacturers, along with experienced installers, can offer a wealth of information and can custom-tailor a system to suit your site.
Home Hydro I t is some w h at rare to find a location that meets all of the practical requirements to make harnessing water power worthwhile. You need access to enough moving and falling water that is reasonably close to a dwelling that can use the power (or to grid power for grid intertie), and you need to secure the required local, state, and federal permits and rights to access the water and harness its power. If such a site is yours, you have struck your own little oil well, and opportunity awaits! Large-scale, alternating current (AC) hydro systems are generally not practical for homeowners due to cost, complexity, regulations, and the volume of water needed to make the investment worthwhile. Micro-hydro systems don’t require much alteration of the stream and so have a minimal impact on waterways and ecosystems. The power generated by a micro-hydro system may be AC or direct current (DC) but will often be converted to DC so the energy can be stored in batteries. In fact, most micro-hydropower systems can be considered battery chargers. One significant advantage to energy storage is that the generator can be much smaller than your peak power demand, relying on batteries and a power inverter to manage and deliver any power surges required by the loads that exceed the output capability of the generator. The iconic image of an old-style water wheel is not the modern way of generating electricity that we’ll explore in this chapter. Water wheels collected water’s energy as it flowed through a river or over a relatively short dam at high flow rates, low pressures, and low speeds. The energy harvested was used for mechanical power, such as grinding grain. Today’s modern hydropower turbines require water to be delivered at high pressure through a nozzle that focuses a jet of water onto a fast-spinning wheel, or runner, which in turn spins an electric generator. The most common way to capture the water energy in micro-hydro systems is to divert part of the stream through a pipeline, or penstock, downhill to the power-generating turbine, which may be sheltered in a small shed or powerhouse along with the required controls. After the water has done its work, it flows back into the river, often through another pipeline, called a tailrace.
How Much Power Can You Make?
There must be enough energy in the water to justify installing a hydro energy system, so quantifying water resource is the first order of business. To estimate the available power of a stream requires the understanding of a couple of key performance factors: • How much water is flowing over a given period of time (flow) • How much pressure (head) can be delivered to the hydropower generator Head and flow will determine everything else about the design of your hydropower system, so you must capture these two parameters first — and with reasonable accuracy. Accuracy cannot be overemphasized: If you want to make the most of the time, money, and labor invested in your power system, you must take accurate measurements. Once you know how much potential energy is available in the water, you can begin to design the systems to collect, control, and store this energy. Those details include:
• Determining the type of turbine that best suits your site
• Working with manufacturers to tailor the turbine specifications to your site
• Sizing the generator capacity — usually a compromise between meeting your power needs, what the water can support, and cost
• Determining how much water must be diverted to support the generator
• Sizing and layout of penstock pipe and wiring
• Determining requirements of controls When you have some understanding of your water power site and requirements for harnessing that power, it’s time to contact a water turbine manufacturer to begin fine-tuning the design, based on the specific equipment you choose. Working with a manufacturer is important because there are many turbine variables that can be customized based on your specific site. Manufacturers, along with experienced installers, can offer a wealth of information and can custom-tailor a system to suit your site.
