micro hydropower for off grid houses

Micro Hydropower For Off Grid Houses: A Comprehensive Guide 2024

Living in a mountain house also has its negative aspects, one of them is constant electricity cut off. Weather on top of all is always unexpected. So keeping my home lightened up was always a concern for me.

Therefore I thought to shift toward solar energy, but it failed due to a lack of continuous sunlight throughout the day. As a homemaker, managing house bills is your topmost priority, and so is mine; therefore, Setting up a generator was also out of choice.

micro hydropower system

Moving with the thought, “Everything has Pros and Cons.” I had many streams and small lakes around my house- which acted as pros for me. I tried researching various details to generate electricity through water. Thereby leading me to the “Micro Hydro system.”

Walking along with the article, I will guide you through all possible information for setting up micro hydropower for off grid houses. Let me first tell you how we can generate electricity through water.

Producing Electricity Through Water

Let’s start with a fundamental question- what do you mean by “Hydropower”? The answer to this question is- deriving energy from flowing or streaming water. A primary principle that follows here is that water pressure in hydroelectric generators rotates the turbine blade, which in turn rolls a generator to produce electricity. The reference taken here is fresh water.

hydropower system

Hydropower generation is a process of making a wall as a barrier in the path of streaming water. Water is then channelized and is made to drop as soon as its kinetic energy is converted into potential energy. The energy produced through this process is then extracted from a turbine. Production of hydropower energy is usually done on a very large scale. The energy produced from this procedure ranges from a few watts to many gigawatts.

First, let me introduce you few important terms-

Water Head refers to the measurement of the hydrostatic energy of water. In simple words-measurement of the height of water available above the turbine (for hydropower).

Flow Rate is the volume of water that crosses a particular point in one second.

The world’s largest hydropower plant is located in China, “Three Gorges Dam.” This hydropower plant has a massive capacity of 22 gigawatts. Energy generated by large-scale hydro projects can power a whole country. Many countries in the world are completely dependent on this source of energy. One such example is NORWAY- which generates 98% of its power from hydro energy.

Hydropower projects are classified as-

  • Pico hydropower projects can produce 5kw or less.
  • Micro-hydro energy projects have a production capacity of 5kw to 100kw.
  • Then comes- Small scale plants, which have a capacity of 10 megawatts or less.
  • Large Scale plant projects produce more than 10 megawatts.

Benefits And Drawbacks Of Hydropower Plants

Every source of energy has its own merits and demerits and so as for hydro energy. Understanding good and bad aspects is very important before setting up a hydropower plant for a house or business. Here I am listing down a few of them-

Merits: One of the cheapest modes of electricity-producing sources. Energy is extracted from a renewable source as the environment renews water through a water cycle—furthermore, No emission of carbon dioxide during the conversion of kinetic energy into usable electricity.

Demerits: Streams and rivers have varied water flow rates throughout the year. Therefore extracting energy from varied flow rates requires different types of turbines.

Types Of Turbines

Three types of turbines are generally available

  1. The Pelton Wheel has a specific speed of 5.0 rpm.
  2. Francis Turbine gives a specific speed of 30 and 70 rpm.
  3. Kaplan Turbine with a specific speed of 113 rpm.

water-turbine

Water head and flow rate have a vice versa relation. The type of turbine to be used depends on the factors mentioned above. When the water head is high and the flow rate is low, the Pelton wheel is used, whereas the Kaplan turbine is used when the situation is vice versa. The former is an impulse turbine, whereas the latter is a reaction turbine.

Francis turbine falls in between the above two- for medium head level and flow rates. Francis turbine is a hybrid turbine that utilizes the impulse of the force along with the action of the force. Additional merit is that this turbine also works as a pump for storage systems. The efficiency of both Kaplan and Francis’s turbines is over 90%.

Cross Flow turbines or Bank II turbines are also available in addition to slow-moving machines. These turbines are used in places where the head level is low but the flow rate is high. These slow-mover turbines are easy to maintain, and bearings work without the need for early replacement due to self-cleansing properties, thereby clogging up less.

A large variety of micro-scale turbines are also available. One of them is Turbines with helical blades that work in the shallowest and slowest of streaming water.

Limitations Of Large-scale Hydropower Plants

Along with the positives, you must also know about the negatives of large-scale plants. A few of them are-

  • Setting up large-scale hydropower plants requires building dams, which is a massive investment.
  • A barrier that is made across streaming water often overflows upstream lands.
  • Construction of dams means demolishing the habitats of several plants and animals along with fish species. Several fish species need upstreams for spawning.
  • People living nearby are also asked to move to leave everything behind.
  • Silt, debris, dead wood, and many other solid clogs decrease the capacity of dams with time.
  • Decayed plantation decomposes into emissions stagnating upstream of the barrier.
  • The construction of dams changes the natural water table in downstream lands.

large-scale hydropower plants

All the above limitations and environmental laws make it difficult to construct hydropower projects on a large scale. Thereby A shift towards several small-scale projects ( run-of-the-river projects) instead of a few large-scale projects is seen in modern times.

Can Hydropower Be Used In Homes Or Businesses? If Yes, How?

Definitely Yes, homes, farms, and small businesses can be fueled by hydropower turbines. A micro-hydro system generates 5-10kw of energy sufficient to power a house, a small farm, or a business. Here impulse types of turbines are used. A micro-hydro system generally uses Pelton Wheels or Turgo Wheel turbines. That’s why micro hydropower for off grid houses is the best option among all types of hydropower.

There are many panels required for mobile home to run in the case of emergency, but you can also use this for emergency purposes during the rainy season.

Hydro energy is also used in pump storage projects along with all the other benefits. The basic ideology behind this is to cope with massive energy demands during peak times. Due to varying electricity demands around the clock, Pump storage provides an energy buffer.

At times when the usage of electricity is less with excess electricity in the grid, water is pushed back into higher level reservoirs from lower level reservoirs using electricity from the grid and turning the turbine in an anticlockwise direction, allowing it to act like a pump. Water pumping elevates the capacity of the reservoir headwater.

Extra water is utilized during peak demand, either during the day or evenings. Water that was pushed back is used with existing and incoming water to move turbines on their peak magnitude.

Home Water Turbine Generator

Run-of-the-river projects are micro-scale hydro schemes that make your life easy by powering your home and rescuing you from hefty electricity bills. In this scheme, a channel is built that transports a small amount of water from streams or rivers to a powerhouse that contains turbines, and therefore these turbines use the water transported to produce power. The powerhouse containing turbines is constructed at a very lower level compared to the spot where water flows into channels from rivers or streams.

home water turbine generator

Next, Let us analyze and understand the calculations for hydropower generation at a particular place. A simple formula or code will direct you to the total calculated power that a turbine can generate in a micro-scale hydro project.

Formula-
P = Nu x Rho x Q x G x H
wherein, P = power (watts)
Nu = Efficiency of a turbine (dimensionless) (92% for Francis and Kaplan turbines)
Rho = Density if water (kg/m3)
Q = Rate of flow (m3/s)
G = Acceleration due to gravity
H = Height difference ( between inlet and outlet in meters)

Although Run-of-the-river projects have returned much less than big-scale hydro projects, these schemes are nature friendly. Also, they can be constructed easily and become ready to use within a very short time compared to large-scale projects requiring a greater amount of time to be constructed.

Can A Micro-scale Turbine Generate Enough Power To Lighten Up A House?

To get an answer to the above query, Let’s start with estimating- how much power a regular home needs around a year. Depending upon the energy consumption in a kWh home, the main question is answered, and then the size and type of turbines are determined.

Two methods can be applied to estimate this calculation:

  1. Totaling the energy ratings in watts of every home appliance and multiplying it by the number of hours each device is used around the year. The calculation here becomes a hectic process, and also, the average taken here might not match reality resulting in insufficient or excess energy. Also, Assessing some devices is very problematic; such as Freezers and A.C. above all, an appropriate power factor can mislead calculations. Therefore the above method is a NO.
  2. An easy and advised method is to have a look at the utility bills for last year. After checking up on the previous year’s bills for the number of kWh energy used, determining the size and rating of the turbine or panel required gets easy.

Let’s take, for example, the amount of energy used in a regular household is approximately 10000 kWh in a year.

Here I have compared power produced by hydro energy turbines and solar energy panels of the same kWh.

A hydro energy turbine of 10kW with consistent water head and flow will produce-

Hydro energy:
10kWh x 8760h (yearly) = 87600kWh

Solar Energy:
10kWh x 1825 (peak-sun-hours per year) = 18250 kWh

Theoretically, A hydro energy system is a much more reliable source than a solar energy system even after including all losses for cabling and fluctuations.

[Video Credit – Land To House]

Is Hydroelectricity Cheaper Than Solar Energy And Wind Energy?

While talking about large scale, it’s an absolute YES. The amount of energy produced through hydro energy is double and the price is half when compared to solar energy on the same parameters. But the difference comes while checking up on other types of scales of power production.

Price is dependent basically on one important factor. One is the output capacity of all three sources of energy. Solar energy output is dependent exclusively on sunlight which varies throughout the day and is weather-dependent. Whereas if the wind blows at double speed, output n watts nearly increases to 8 times. Hydro energy output will always be maximum in watts in the availability of constant water and flow rate.

Micro Pump Hydro Storage System

Micropump hydro storage system, as the name suggests, is simply a storage System of hydro energy that works as a replacement for chemical battery storage and works with any scale of hydro energy projects.

Having a house with a lake or streaming water nearby your house and you plan to have an off-grid system with panels installed on your rooftop and a higher level inclination of the lake near the house. When there is a lack of sunlight or at night when the sun is down, a need for battery backup will be felt but again it comes with hefty bills.

micro pump hydro storage system

Therefore developing a Micro pumped hydro storage system comes into being as an answer. When sufficient sunlight is available, panels help lighten up the house, and water is pumped to storage systems at higher levels from ponds or lakes.

At dark, with no solar energy output, water stored in the reservoirs is left to flow. It is therefore rotated through a turbine working as a generator, producing electricity at night too.

Water Flow Required To Generate Electricity

Here I have figured out easy and convenient ways to determine the flow rate. But when investing a hefty amount of money in a hydro energy power plant for your house, I advise you to consult a professional surveyor for the most relevant information.

The water head is estimated by measuring the length of the pipe from the spot where the stream comes from (highest elevation) to the turbine(powerhouse) location. The lower end is connected to a pressure gauge to which psi is estimated.

Suppose a Water head of 2.31 feet =1 psi.

Flow rate is measured easily by counting the number of seconds required to fill a bucket with a well-known known capacity(water flow from a small stream or lake). Flow rate is measured in gallons/minute.

Flow rate(gallons/min) = 60/seconds taken x bucket capacity in gallons
Suppose A 5-gallon bucket is filled in 10 seconds
Water flow(gallons/min) = 60 / 10 x 5 = 30 gallons/ min

A micro hydro power calculator is used to determine how much watt turbine will be required with help of flow rate and head level. The system provides an efficiency of approximately 50-60%.

The equation goes as:
Power(watts) = {Head(feet) x flow rate(gpm)} ÷ 10

Let me make it easier for you to understand the calculations better through an example:
Head psi = 40. Flow = 70 gallons/min

As per the formula head is required in feet, therefore
Head (feet) = 40 x 2.31 = 92.4 feet
Turbine Power:
Power(watts) = head x flow rate / 10
92.4 x 70 / 10
= 646.8W

If you want more detailed information about installing a micro hydropower system for your off-grid house, click here.

 

Frequently Asked Questions:-

  • How is the hydroelectric source of energy different from solar or wind energy?

Solar energy is most common but is mostly dependent on direct sunlight. Wind energy is only viable in a few areas and turbines also need a constant wind speed of 5m/second to roll on. Water turbines need constant streaming water but have maximum electric output.

  • Does hydropower need batteries?

The answer is NO, with an assumption of constant water flow. While in otherwise cases, such as when connected to a grid, batteries are required. During a power cut the hydropower system gets disconnected from the grid leading to a blackout in the home.

  • How much water head and flow rate are required to generate power for a regular home?

An easy formula to calculate the amount of water required to power a house is as-

Head (feet) x flow rate (gpm)÷ 10= Power(watts)

A 4kW turbine is required to power a house, then a product of water head and flow rate must be 4000 watts.

  • How much does a micro-scale hydropower system cost?

Though the investment cost widely depends on a head level, flow rate, power consumption, type of turbine, pipelines, etc., Theoretically, the cost is around $1000- $3000 per kW.

 

Conclusion

I have always wanted to share my thoughts about a source of energy that has helped me in lighting up my house for ten years. The best part about hydro energy is that it produces energy around the clock. An additional benefit is that when the system is down, it can be repaired by oneself instead of depending on the power company. Yup, The fact that it requires a bit of a high investment initially is true but will save you from heavy bills in the future.

Concluding with my final thought, I think I have put a solution to all your questions regarding setting up a “micro hydropower system” with an off-grid system. Now it will be easy for you to make your home a hydro-powered household. I suggest you phone a professional for more accurate estimations according to the location and many other factors.

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Ray is an avid reader and writer with over 25 years of experience serving various domestic and multinational private and public energy companies in the USA.

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