Power can be supplied by a micro hydro system in two ways. In a battery-based
system, power is generated at a level equal to the average demand and stored in
batteries. Batteries can supply power as needed at levels much higher than that
generated and during times of low demand, the excess can be stored. If enough
energy is available from the water, an AC-direct system can generate power as
alternating current (AC). This system typically requires a much higher power level than
the battery-based system.
Battery-Based Micro Hydro Systems
Most home power systems are battery-based. They require far less water than AC
systems and are usually less expensive. Because the energy is stored in batteries, the
generator can be shut down for servicing without interrupting the power delivered to
the loads. Since only the average load needs to be generated in this type of system,
the pipeline, turbine, generator and other components can be much smaller than
those in an AC system.
Very reliable inverters are available to convert DC battery power into AC output (120
volt, 60 Hz). These are used to power most or all home appliances. This makes it
possible to have a system that is nearly indistinguishable from a house using utility
power.
The input voltage to the batteries in a battery-based system commonly ranges from
12 to 48 Volts DC. If the transmission distance is not great then 12 Volts is often high
enough. A 24 Volt system is used if the power level or transmission distance is
greater. If all of the loads are inverter-powered, the battery voltage is independent of
the inverter output voltage and voltages of 48 or 120 may be used to overcome long
transmission distances.
Although batteries and inverters can be specified for these voltages, it is common to
convert the high voltage back down to 12 or 24 Volts (battery voltage) using
transformers or solid state converters. Articles on this subject appeared in Home
Power # 17 and #28. Wind or solar power sources can assist in power production
because batteries are used. Also, DC loads (appliances or lights designed for DC) can
be operated directly from the batteries. DC versions of many appliances are available,
although they often cost more and are harder to find, and in some cases, quality and
performance vary.
AC-Direct Micro Hydro Systems
This is the system type used by utilities. It can also be used on a home power scale
under the right conditions. In an AC system, there is no battery storage. This means
that the generator must be capable of supplying the instantaneous demand, including
the peak load.
The most difficult load is the short-duration power surge drawn by an induction motor
found in refrigerators, freezers, washing machines, some power tools and other
appliances. Even though the running load of an induction motor may be only a few
hundred Watts, the starting load may be 3 to 7 times this level or several kilowatts.
Since other appliances may also be operating at the same time, a minimum power
level of 2 to 3 kilowatts may be required for an AC system, depending on the nature of
the loads.
In a typical AC system, an electronic controller keeps voltage and frequency within
certain limits. The hydro's output is monitored and any unused power is transferred to
a "shunt" load, such as a hot water heater. The controller acts like an automatic
dimmer switch that monitors the generator output frequency cycle by cycle and diverts
power to the shunt load(s) in order to maintain a constant speed or load balance on
the generator.
There is almost always enough excess power from an AC micro hydro system to heat
domestic hot water and provide some, if not all, of a home's space heating.
< Micro Hydro Part I Part III Micro Hydro System Components >
system, power is generated at a level equal to the average demand and stored in
batteries. Batteries can supply power as needed at levels much higher than that
generated and during times of low demand, the excess can be stored. If enough
energy is available from the water, an AC-direct system can generate power as
alternating current (AC). This system typically requires a much higher power level than
the battery-based system.
Battery-Based Micro Hydro Systems
Most home power systems are battery-based. They require far less water than AC
systems and are usually less expensive. Because the energy is stored in batteries, the
generator can be shut down for servicing without interrupting the power delivered to
the loads. Since only the average load needs to be generated in this type of system,
the pipeline, turbine, generator and other components can be much smaller than
those in an AC system.
Very reliable inverters are available to convert DC battery power into AC output (120
volt, 60 Hz). These are used to power most or all home appliances. This makes it
possible to have a system that is nearly indistinguishable from a house using utility
power.
The input voltage to the batteries in a battery-based system commonly ranges from
12 to 48 Volts DC. If the transmission distance is not great then 12 Volts is often high
enough. A 24 Volt system is used if the power level or transmission distance is
greater. If all of the loads are inverter-powered, the battery voltage is independent of
the inverter output voltage and voltages of 48 or 120 may be used to overcome long
transmission distances.
Although batteries and inverters can be specified for these voltages, it is common to
convert the high voltage back down to 12 or 24 Volts (battery voltage) using
transformers or solid state converters. Articles on this subject appeared in Home
Power # 17 and #28. Wind or solar power sources can assist in power production
because batteries are used. Also, DC loads (appliances or lights designed for DC) can
be operated directly from the batteries. DC versions of many appliances are available,
although they often cost more and are harder to find, and in some cases, quality and
performance vary.
AC-Direct Micro Hydro Systems
This is the system type used by utilities. It can also be used on a home power scale
under the right conditions. In an AC system, there is no battery storage. This means
that the generator must be capable of supplying the instantaneous demand, including
the peak load.
The most difficult load is the short-duration power surge drawn by an induction motor
found in refrigerators, freezers, washing machines, some power tools and other
appliances. Even though the running load of an induction motor may be only a few
hundred Watts, the starting load may be 3 to 7 times this level or several kilowatts.
Since other appliances may also be operating at the same time, a minimum power
level of 2 to 3 kilowatts may be required for an AC system, depending on the nature of
the loads.
In a typical AC system, an electronic controller keeps voltage and frequency within
certain limits. The hydro's output is monitored and any unused power is transferred to
a "shunt" load, such as a hot water heater. The controller acts like an automatic
dimmer switch that monitors the generator output frequency cycle by cycle and diverts
power to the shunt load(s) in order to maintain a constant speed or load balance on
the generator.
There is almost always enough excess power from an AC micro hydro system to heat
domestic hot water and provide some, if not all, of a home's space heating.
< Micro Hydro Part I Part III Micro Hydro System Components >
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Alternative-Heating-Info.com
Micro Hydro Systems: Part II
If electric heating loads are
excluded, 300-400 Watts of
continuous output can power a
typical North American house.
This includes a refrigerator /
freezer, washing machine,
lights, entertainment and
communication equipment, all of
standard efficiency.
With energy efficient appliances
and lights and careful use
management, it is possible to
reduce the average demand to
about 200 Watts continuous.