This page is part of the Highest Good energy™ component of One Community and an open source guide to hydro power applications for the Duplicable City Center®, 7 different communal living mini-village designs, and similar projects. It is purposed to help people understand the how’s and why’s of various mini and micro hydro-energy design options, setup, maintenance, and costs for replication.
We discuss the results of our research with the following sections:
Hydropower, also known as hydroelectric power, is a renewable source of energy that takes advantage of three natural phenomena – gravitational force, the water cycle, and electromagnetic energy. Hydropower extracts energy from moving water to create a more useful form of energy – electricity. It is considered renewable because it is non-consumptive (water in and water out) and relies on the water cycle. This boundless and constantly recharging phenomenon is powered by the sun and, practically-speaking, an inexhaustible energy source. The simplest and most recognized form of hydropower is the waterwheel. Modern inventions though have resulted in technologies with greater efficiencies and power storage capabilities, such as turbines and batteries. Hydropower is currently the largest emission-free, renewable source of electricity worldwide. The main drawback of hydropower is site specificity – requiring a reliable and sufficient amount of water flowing from a sufficient height.
Sustainable and open-source-replicable energy infrastructure is part of One Community’s goals for helping create self-replicating and sustainable teacher/demonstration hubs collaborating for positive global change. What we see as missing, for those with a cleaner and more sustainable vision of electric power, is helpful guidance and do-it-yourself tutorials. Millions of people around the globe still lack reliable electricity and governments are still years away from connecting all these places with their respective large-scale grids. We’re open sourcing hydro energy design and setup to show how people can create electricity for themselves.
With the advent of the different types of renewable energy sources like mini and micro-hydro, wind, solar, biogas, etc. and their constantly decreasing prices, the ability for people to create their own renewable power source is better than ever before. Add appropriate technical know-how of renewable energy systems, and installation can be fairly easy.
This has the potential to help:
Additionally, in places where there is flowing water, hydropower can be the best renewable energy option available. With this open source hydro energy system tutorial, we hope to provide a replicable and easy-to-follow path to assessing, designing, installing, operating, and maintaining your own hydro energy system. The easier, more affordable, and more attractive hydro energy can be demonstrated, the more people will adopt it.
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The One Community Core Team
Yomi Sanyaolu: Mechanical Engineering Graduate and Technical Writer
Now let’s talk about hydro power/energy and its applications. Much of the content of this page came from two really good resources we found and would recommend. Micro-Hydropower System – A Buyer’s Guide and Micro-Hydro Power A Beginners Guide to Design and Installation. A simplification and reorganizing of that information was helpful though. So, if you’d like just the most relevant information and results from our additional research, we cover all that here with the following sections:
It is helpful to have a rudimentary understanding of energy when discussing the generation of electricity. Energy is the ability to do work. Energy can be transformed or transferred from one system to another. Each kind of energy (kinetic, potential, electrical, etc.) has engineering units associated with it that allows us to mathematically quantify each kind and to predict how much of one kind will be present when transformed from another. Mathematically, energy is the product of some form of effort (force, volts, torque, etc.) and some form of flow (distance, amperage, rotation, etc.).
Power is different. Power is the amount of energy available to be transformed in a given amount of time. For example, propelling a vehicle forward one mile requires a certain amount of energy, regardless of how quickly (ignoring the effects of drag). The amount of time it takes for the vehicle to move one mile is determined by how quickly the energy source can be transformed, or more specifically, how much power is available. Power is quantified by dividing energy by some unit of time.
In the case of hydropower, instead of the water freely flowing downhill towards the sea, flow is directed past a turbine. The flowing water pushes against blades on a turbine, which spins the turbine and rotates a shaft containing magnets inside coils of wires that produces a flow of electrons, generating electrical energy. Essentially, hydropower is the process by which the potential energy in water on high ground is converted to kinetic energy of water flowing downhill, followed by converting it to mechanical energy, then rotational, and lastly electrical energy.
The maximum amount of energy produced through the conversion of the potential energy in water to electrical energy or ‘water to wire’ is directly related to flow rate, head (or pressure), and energy losses due to inefficiencies. Flow rate is the volume of water flowing past a given point over a set time period. It can also be defined as the amount of water flowing through the turbine over a given time interval. Most common units include gallons per minute (gpm), cubic feet per second (cfs), cubic meters per second (m3/s), and liters per second (L/s). Flow is represented with the symbol Q. Details on measuring flow rate are provided in the ATTRA publication Micro-Hydro Power A Beginners Guide to Design and Installation (pages 2 – 5). Ideally, the minimum flow over the year should be used as the design flow for power calculations. This ensures year-round power.
Head is the pressure at the turbine inlet due to gravitational forces acting on the water’s mass and increases with elevation (elevation head) and depth of water (pressure head). Head is represented with the symbol H. In practical terms, head is the vertical distance from the water surface (in the case of a dam) or the point where the water enters the intake (in the case of no dam, like mini or micro-scale applications) to the midpoint of the turbine. Head can also be defined as the vertical distance the water has fallen as it hits the turbine. Details on measuring gross head are provided in the ATTRA publication Micro-Hydro Power A Beginners Guide to Design and Installation (pages 6 – 7).
As described here, and shown in the image below, gross head is the total vertical distance between the intake and turbine:
The generating potential of a given property can be estimated using the following calculations:
Flow (gallons per minute) × Head (Feet) / 5 = Watts of Output
Flow (m3/s) × Head (Meters) × 10,000 = Watts of Output
Flow (Liters per second) × Head (Meters) × 10 = Watts of Output
(note: This formula is for continuous output.
To determine kilowatt-hours per day,
multiply answer by 24 hours x 1kW/1000W or 0.024)
Roughly speaking, 2 gallons of water per minute (average flow of a kitchen faucet) falling 20 feet (average height of a 2-story building) can generate 8 watts of electricity (note: this is theoretical potential and does not account for system inefficiencies covered in the next paragraph). 8 Watts is enough to power an LED light, a home internet router, or 8 night lights. The following table provides theoretical power output in Watts for different head and flow rate combinations (as a reference, the average height of a 2-story building is 20 feet and the average flow of a kitchen faucet is 2 GPM) :
Not all energy is 100% transformed into the desired form of energy. Some energy is dissipated, lost, or ‘wasted’ before it is converted to the desired form(s) of energy. All losses are due to some form of friction, which is the dissipation of energy to heat when two things rub against each other. The inefficiencies of a system accounts for these losses. In the case of hydropower, some of the potential energy in the water is dissipated along its path to electrical energy. Individual inefficiencies can be determined for losses through the pipeline (head loss), and losses through each component of the system, such as turbine, generator, battery, and power line.
Head loss is the energy dissipation from wall effects as the water flows through a pipe and around bends, as well as the viscosity of the water. Multiple tools are available online for the calculation of head loss, such as this one. “Net head” is the head available after accounting for losses. Net head is often assumed to be 20 percent of gross head. Inefficiencies of most other components are typically provided by the manufacturer. Often, these energy losses are lumped together and accounted for using the “water-to-wire” efficiency factor. Typically, overall ‘water to wire’ efficiencies range from 50 to 70 percent. As a rule of thumb, 50 percent for systems generating less than 10kW and 60 to 70 percent for systems generating over 10 kW.
The following calculators provided by micro-scale hydropower system suppliers provide a more detailed determination of the power generation potential of a given property:
You can also download a free renewable energy project analysis software program to evaluate if a micro-hydropower system is economically sensible for a particular site.
Power is often expressed as of watts (W), kilowatts (kW), or megawatts (MW), and mechanical power is measured in horsepower (HP). When expressed as kW, this is the instantaneous work that the water does in the process of generating electrical work. To determine the work or electricity generated annually, one would multiply the work by 24 hr/day and 365 days/year. For example, if a turbine generates 150 watts continuously for an hour, it will have generated 150 watt-hours, or 0.15 kilowatt-hours (kWh).
There are three ways to harness the energy in water on high ground:
The system can either be connected to the main grid or isolated to supply decentralized local needs. Hydropower systems are typically classified according to their power generation capacities and categorized into small and large, with small commonly being further broken down to mini and micro:
Small: Less than 10-30 MW
–Micro: 1 kW to 100 kW
–Mini: 100 kW to 1 MW
Large: Above 10-30 MW
The upper bounds for a small system are not internationally agreed upon and range from 10 to 30 MW. Although definitions vary, the US Department of Energy defines small hydropower systems as generating 10 MW or less of power and the US National Hydropower Association specifies a minimum limit of 5 MW.
Large-scale applications are typically impoundments (or dams) or pumped storage. Small hydropower is typically built using existing infrastructure, including existing dams, canals, and pipelines or diversions.
Mini- and micro-hydropower applications are comprised of these primary components:
For communities with similar supplemental power needs as One Community, mini or micro-scale hydropower is applicable. Although a run-of-river system is ideal at these scales, the potential for hydropower is apparent even with small flows generated by rainwater traveling down a gutter, as demonstrated in a 4-part series by Quint BUILDS. Here’s the first video:
Using simple technology, Quint was able to put together a system that was about 40% efficient, ultimately generating 1 W of power, which easily charged a flashlight and lit up a string of Christmas lights. So, although there are ideal situations to have hydropower, its application should not be dismissed just because all criteria are not met. Quint used a flow rate of 1.9 GPM (which he calculated based on an average rainfall of 0.2 in/hr on a 900 ft2 roof), a head of 5.9 feet, and a pelton turbine that he made on a 3D printer. With this configuration, the theoretical power generation potential was 2.1 W and he was able to generate about 1 W of power.
Micro-scale hydropower is best suited and most commonly implemented on properties with streams that flow even during the summer but don’t flood in the spring, and with slopes that are relatively steep for sufficient head. A greater amount of energy is generated when large volumes of water flow over a steep gradient. The minimum head and flow rate requirements are difficult to specify because a combination of high values of one with low values of the other can result in useful power generation. For this reason, there is not a general consensus regarding minimum head and flow rates.
According to the Natural Resources Canada Government Department, there is no economic advantage to pursuing projects that have less than 3 feet (0.9 meters) of head or flow rates less than 10 gpm (0.0006 m3/s). ATTRA also specifies a minimum of 3 feet of head is required to implement hydropower, whereas a minimum of 10 feet is necessary for an economically viable project. The Department of Energy claims greater than 2 feet is necessary. Using this information, we’d say that at least 3 feet of head should be available with 10 gpm flow, which will result in a theoretical power generation of about 6 Watts.
The core part of a hydropower system is the turbine. The choice of the turbine is dependent on the available head and flow, as summarized in the following table:
Turbines typically fall under 1 of 2 categories: impulse or reaction.
Impulse turbines convert the potential energy of the water to kinetic energy using a nozzle that creates a jet of water. The fast moving jet hits the turbine’s curved blades, causing the turbine to rotate. Impulse turbines have a simple design and are widely used for micro-scale hydropower applications.
Reaction turbines are completely submerged in a large volume of water and the turbine rotates as the water flows past its blades, like air flowing past a wind turbine. Reaction turbines are typically used for large-scale hydropower applications, with the exception of Kaplan turbines, which have an adaptable propeller system, making them applicable in high-flow, low-head micro-scale applications.
Pump-as-Turbine (PAT) is another reaction turbine option. In this case a centrifugal pump, running in reverse, serves as the turbine. This is an inexpensive alternative, costing 50% or less than turbine options discussed above. The main drawback is that they are usually limited to a narrow flow range as compared to the above alternatives.
Whatever your hydro energy project, manufacturers can assist with turbine selection. The following sites were found of promising manufactures and providers:
Although there are many exceptions when it comes to selecting a turbine, the following plot summarizes the criteria for turbine selection:
There are a variety of other components to consider in addition to turbines. In essence, a micro-scale hydropower system works just like a wind turbine, except it extracts energy from a denser fluid (water) than a wind turbine (air). The research we have completed in relation to establishing a wind microgrid can be used to select the additional equipment for hydropower implementations too.
The following references were helpful creating the section above.
Here’s a free and open source turbine that can be built for half the cost of a 120 watt solar panel, and will produce about ten times the power (5kWh with 3m drop and 35 l/s flow) per day. It can be plugged into any appropriate waterway without the need for earthworks, and uses only basic off the shelf and recycled materials and simple hand tools. Details on materials, tools, and step-by-step build instructions are available here on the OpenSourceLowTech.org webpage about this.
Because run-of-river applications are common, several examples of run-of-river applications can be found online and throughout the Micro-Hydropower System: A Buyer’s Guide (Pages 7, 8, 10) and here. We also explored some less common applications, to understand sites that do not have ready access to flowing surface water, such as a river or stream. In this section we share and discuss the following possible scenarios:
To determine the energy output from your scenario, you may find our calculator useful. Here it is:
We used the following equation and assumptions for the scenarios described below:
P = Q x H x g x ? x ?
P = power,
Q = flow rate moving through the turbine, m3/s
H = gross head or vertical distance water has fallen when it hits the turbine or head, m
g = acceleration from gravity = 9.8 m/s2
? = density of water, typically 1000 kg/m3 for the applicable temperature range these systems operate in
? = “water to wire” efficiency factor, unitless, typically 0.5 for small-scale operations
Here is a summary of some scenarios that we explored for sites without a stream on the property, such as the potential property for One Community.
This scenario looks at using the water in earthen dams that are supplied water naturally using swales, rainwater, and groundwater flows (see our open source dam design page). This scenario explores using a turkey nest dam that holds 0.6 million gallons of water (enough for fire suppression) and is assumed to be naturally replenished at a rate that is equal to a single turnover annually. The gross head is 53 m (175 ft) and the flow rate is 0.0001 m3/s (1.1 gpm), which is 0.6 million gallons per year. To achieve a 175-foot (53 meters) drop requires a pipeline that is 2,723 feet long (830 meters). This system has the potential to generate approximately 20 W using a ‘water to wire’ efficiency of 0.5. This scenario was assessed to determine the opportunity with extracting energy from an earthen dam and it was deemed infeasible for this particular scenario. However, if the flow rate was any higher, this could easily be a viable solution for us.
This scenario explores using the flow from natural springs on the potential property. Using an estimate provided in a Water Rights document, 8 GPM, and gross head of the highest spring, 140 feet, as well as a ‘water to wire’ efficiency of 0.5, the highest spring has the potential to generate 105 Watts using a 2200-foot pipeline. Given its distance from the Duplicable City Center (2200 feet), this option is also not viable. However, before forgoing this scenario, the flow rate should be verified for the two springs that are higher than the planned City Center.
This scenario explores using the potable water flow to the City Center and the Earthbag Village (Pod 1), which will be supplied by the springs on the property. If the entire supply is from the spring at the highest elevation and 30 psi is maintained at the point of use, the remainder of the head can be applied to produce power. 30 psi is equivalent to about 20 feet of elevation head, which leaves about 20 feet of elevation head for power generation. With a water demand of 2200 GPM, 20 feet of gross head, and ‘water to wire’ efficiency of 0.5, this configuration has the potential to provide 15 kW of power. This configuration is worth pursuing further.
This scenario explores using the greywater flow from the builds where they are generated to treatment ponds. The flow rate is 20 GPM and the elevation head is approximately 10 feet. Using a ‘water to wire’ efficiency of 0.5, this scenario has the potential to produce about 20 Watts. This is an option worth looking into further.
Costs associated with hydropower include capital (or initial up-front investment) and operation and maintenance (O&M) costs. Capital costs are mainly due to intake structure, pipelines, turbine, generator, controller, transmission line, and powerhouse, as well as other miscellaneous costs, such as permits, legal work, and installation costs, if outsourced. The capital cost of a do-it-yourself system is generally $1,500 to $4,000/kW. Here is a cost breakdown.
Those systems generating less than 5 kW and systems with low-head (<32 ft) and high-flow generally cost more up-front. O&M costs typically include clearing intake screens, unclogging nozzles, replacing deteriorated hoses and fittings, and replacement of damaged equipment. A decent estimate of annual O&M cost is 5% of the capital costs, so $75 to $200/kW per year. And the life of the system is typically assumed to be 20 or more years. This information was extracted from Micro-Hydro Power A Beginners Guide to Design and Installation. This document also provides a Cost Estimate Worksheet on Page 25:
A list of potential consultants and equipment suppliers is provided above. Most of these suppliers are willing to help with the design process (equipment selection) at no cost. Rocky Hydro is particularly interesting. This company will complete a preliminary assessment given your site’s criteria for a flat fee of $50.
There are federal incentives in place for renewable energy systems, however, most hydropower systems are not eligible. It is beneficial to double check any incentives offered by the federal and state government, as well as local utilities. These incentives can come in the form of property tax and/or sales tax exemptions. For example, the USDA offers 25% grants up to $500,000 and options for guaranteed loans for up to 75% of the total project costs through its Rural Development Energy for America Program (REAP) to agricultural producers or small businesses that are not currently connected to the grid. More information can be gathered by contacting your energy coordinator. You can find your energy coordinator at NCAT’s Directory of Energy Alternatives or by calling your local Rural Development office. Also, the following database is available and searchable by state for a list of potential incentives: Database of State Incentives for Renewables and Efficiency (DSIRE).
It is important to contact your state and county engineer to verify your right to use the water, even when it is for something non-consumptive like hydropower. All hydropower facilities that are tied to the grid must be approved by the Federal Energy Regulatory Commission (FERC). Approval and permits may also be required by other state and federal agencies, such as Fish and Wildlife, Historic Preservation, and U.S. Corps of Engineers. The FERC’s Small/Low-Impact Hydropower Program reduces regulatory burden by allowing facilities that generate under 5MW and use existing dams or conduits to apply for exemptions. This step towards regulatory compliance is a process that takes anywhere from 3 to 24 or more months. To aid in the permitting process, it is beneficial to mention that your intended use is beneficial and non-consumptive. Permitting is often the most cumbersome and time-consuming component of developing a hydropower project, regardless of size. Taking the time to review and maintain regular communication with FERC will result in a smoother process.
If we end up implementing hydropower on the One Community property, we’ll add here our specific experience and recommendations related to regulation.
The following are resources we found relevant and helpful. This includes all the resources included in the reference sections above as well as additional ones.
Trompes are one of the earliest air compressor devices, they were originated back in the iron ages and used mainly for providing air for forges2. Simply put, a trompe is a system that uses the energy from water falling down a tube/shaft to pressurize air coming into that same shaft from the atmosphere. Here’s a picture showing the general design:
Here’s an excellent video that talks about their history and shows how they work:
While trompes have long been abandoned for more modern technologies, they could still be used today. We explore their design and use it with the following sections.
This section includes:
Aside from the original use for providing a constant supply of air to forges, there are many other uses for the pressurized air produced by trompes which include3:
The pros and cons of trompes as a system, are summarized in the table below:
These are the design specification for the trompe system pictured below. For the minimum design criteria/dimensions needed to build a working trompe, see the DIY tutorial in the next section.
An example of a small-scale trompe construction tutorial on LostTechnlogy.org was the main source of the information that follows15. The image here shows this home-made trompe. The assembly steps below are what we’d consider as the bare minimum to construct a DIY trompe. Reduction of any of the dimensions and/or removal of any parts could result in failure of the system. Visit the source article if you’d like more detailed instructions.
See the above image for what this finished trompe system should look like.
Here is a table that includes an example of the needed materials and tools to build the trompe above.
The following are the superscript references numbered in the section above.
A ram pump is a device that uses the momentum of large amounts of falling water to pump a smaller amount of water upwards1. The system operates automatically, with only two moving parts: a delivery valve and a waste valve2. We discuss ram pumps here with the following sections:
The best explanations we’ve found for how a ram pump works are the following two videos.
As earlier mentioned, ram pumps are used to transport water to heights above its source by using the potential energy of falling water; the minimum height drop of water needed for the pump to work is around 20 inches2. For every 1 foot of head (water drop), you can lift the water up to 7 feet; this is a conservative approximation3. There is virtually infinite potential for how long the delivery pipe can transport water e.g. 5km.
A big issue with these systems though is that only 10% of the water flowing through the ram is pumped by the delivery pipe, with the rest being dispersed out of the system. If the ram pump is situated at a pond or river, then the dispersed water can potentially return to its original source. Other use options for the waste water could possibly make this more sustainable too.
Examples of applications ram pumps can be used for are: feeding water into a household, agricultural irrigation, and sewage treatment. See below an insightful diagram from here and explaining the entire process.
Here is a table summarizing the pros and cons of a ram pump.
Provided below is a summary of the DIY process for constructing a ram pump system. All the resources needed can be sourced from Home Depot and cost approximately $100 (USD). For the source of the design below, we strongly suggest visiting this “Hydraulic Ram Pump” Instructables article. The following is just a photo of the design but the source page contains complete instructions.
The construction steps can be summarized as follows:
Visit original source http://www.instructables.com/id/Hydraulic-Ram-Pump/ for assembly pictures, cost analysis details, troubleshooting, improvements to the design and more.
The following are the superscript references numbered in the section above.
In this section, we shall explore the use of a trompe and ram pump as one system so that we can collect pressurized air whilst pumping water. Several questions come to mind when attempting to devize such a system: Is it more efficient to run the systems separately? Is water flow at the output of trompe fast enough to initiate the water ram effect? Will it even work?
Thankfully, there is a YouTube video demonstrating this system in action. Here it is and below the video we its contents:
Once on the property, One Community will open source project-launch blueprint the complete process of installing and maintaining any hydro-energy infrastructure we end up using. We will do this for everything we think will be helpful for those replicating our system(s) as part of the One Community complete open source self-sufficient teacher/demonstration community, village, and/or city model. Upcoming resources will include:
The following are resources we found relevant and helpful. This includes all the resources included in the reference sections above as well as additional ones.
Here are some extra related videos that we found interesting:
Use this page (click here) if you have a resource you’d like to suggest be added here
All the hydro-power systems on this page have useful applications. Micro hydro-power systems are probably the most practical though. Trompes are environmentally friendly and very useful devices for obtaining pressurized, cool and dry air without the use of moving parts, but there are limited uses for pressurized air. Ram pumps have only two moving part and can elevate a small percentage of water but the rest is wasted in most cases. Because of this waste, we’d say pressurized air has a wider variety of applications compared to the uses for small percentages of water that could be elevated. Putting a trompe and ram pump together is possible but not very useful due to their different applications and low efficiency. The only benefit we found in combining them is that the ram pump effect can be used to allow more air and a higher pressure to be achieved in the storage tank of a trompe.
Q: For small-scale use, what would you say would be the best/most practical use of a DIY trompe?
A rechargeable air compressor can be purchased for less than the cost of the DIY trompe described on this page. That said, nonstop aeration of an aquaponics or large-scale fish tank is a useful application. Check out this video of a system using a trompe for this:
Q: For small-scale use, what would you say would be the best/most practical use of a DIY ram pump?
If you have a reliable source of water, a ram pump is an amazing way to move water from a low point to a high point. If wasting water is not something you wish to do, you can buy a small rechargeable or electric water pump for less than the cost of the DIY ram pump version described on this page. It would require power but not waste water.
Q: How does One Community plan to implement trompes?
If we decide to implement trompes, we think air conditioning applications and water aeration would be the most likely uses.
Q: Does One Community plan to implement ram pumps?
As of right now, there is no plan to implement them due to the excessive amounts of water wasted.
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