Micro-hydro systems use the motion of flowing water to generate electricity for a home, farm, school, or small village. They are renewable because the water cycle continually refills streams and rivers. Unlike solar and wind power, a stream can often provide steady energy day and night if the flow is reliable.
This makes micro-hydro especially valuable in mountainous or rural areas with nearby flowing water.
Key Facts
- Hydropower input power is P = ρgQh, where ρ is water density, g is gravitational field strength, Q is flow rate, and h is head.
- Useful electrical power is Pout = ηρgQh, where η is the overall efficiency of the turbine and generator.
- Head is the vertical drop of the water, and more head usually means more available energy per liter of water.
- Flow rate Q is the volume of water passing each second, usually measured in m^3/s or L/s.
- A turbine converts moving water into rotation, and a generator converts that rotation into electrical energy.
- Micro-hydro systems are often less than 100 kW and can power homes, workshops, or small communities.
Vocabulary
- Micro-hydro
- A small-scale hydropower system that uses flowing water to generate electricity for local use.
- Head
- The vertical height difference between the water intake and the turbine.
- Flow rate
- The volume of water that moves through a pipe or channel each second.
- Turbine
- A rotating machine that extracts energy from moving water.
- Generator
- A device that converts mechanical rotation into electrical energy using electromagnetic induction.
Common Mistakes to Avoid
- Using stream speed alone to estimate power, which is wrong because micro-hydro power depends mainly on flow rate and vertical head.
- Forgetting efficiency, which is wrong because real turbines, pipes, and generators always lose some energy to friction, turbulence, and heat.
- Mixing liters per second with cubic meters per second, which is wrong because 1 m^3/s equals 1000 L/s and the power calculation will be off by a factor of 1000.
- Assuming all stream water can be diverted, which is wrong because systems must leave enough water for ecosystems, other users, and legal flow requirements.
Practice Questions
- 1 A micro-hydro site has a head of 12 m and a flow rate of 0.030 m^3/s. If the overall efficiency is 60 percent, calculate the electrical power output using ρ = 1000 kg/m^3 and g = 9.8 m/s^2.
- 2 A village needs 2.5 kW of continuous power. A stream provides 25 L/s through a turbine with 70 percent efficiency. What head is required? Use ρ = 1000 kg/m^3 and g = 9.8 m/s^2.
- 3 Explain why a small stream with a large vertical drop may produce more useful power than a wide slow stream with very little drop.