Updated: October 11, 2023
By Drew Schiavone
Water flowing in creek

Hydroelectric schemes use gravity to drive water through turbines, converting that energy into electricity. Schemes need continuous, year-round water supplies and vertical drops for water to fall down. Water from streams, rivers or dams flows down steep pipes into turbines, which drive power generators. The water then flows back into a river or stream below the hydro plant. Run-of-river systems, which don’t have dams, need water to flow year-round down rivers that have steep enough natural drops to power their turbines. Large scale generation schemes (above 10 MW capacity) are more difficult and expensive to build, but produce large amounts of electricity at low cost. Smaller scale generation (below 10 MW capacity and including micro-hydro schemes that generate less than 10 kW), can be cheaper and easier to build and get consent for, but generate less electricity at a higher cost.

Hydroelectricity systems use the force of running water to turn turbine blades, which spin a shaft connected to a generator. On rural sites they can be set up wherever water falls from a higher lever to a lower level, for example a waterfall, hillside, stream, or where a reservoir discharges into a river. The type of turbine you need depends on the vertical distance the water falls and the rate the water flows. Pelton wheels are the type of turbine most commonly used for small scale domestic generation. If your small scale hydro scheme does need a dam or other form of water storage, you’ll need to get consent.

Understanding Hydropower

How does Maryland use hydropower?

Hydropower accounts for more than half of the state's renewable electricity generation. The Conowingo hydroelectric generating station, located in northern Maryland on the Susquehanna River, was the largest power plant ever built when it began operating in 1928. The 11 turbines at the power station have a combined summer generating capacity of 572 megawatts. Conowingo provides almost all of Maryland's hydroelectricity and it is one of the five largest electricity producing plants in Maryland based on actual yearly generation.

Hydroelectric plants marked on US map

What are micro-hydro systems?

If you have access to the right stream or waterway, micro-hydro can be a reliable and economic way to generate your own electricity. Many small hydro schemes already exist on rivers and streams within the region, and there are more opportunities to use water driven generation for remote farms and homes. Small scale hydroelectric facilities are generally classified into three sizes:

  • micro-hydro - up to 5 kW
  • mini-hydro - between 5 kW and 20 kW
  • small commercial hydro - between 20 kW and 10 MW
Microhydro Generator by Stream

Micro-hydro systems for houses and buildings are less than 5 kW, and in many cases less than 1 kW. Micro-hydro systems are best suited to rural areas on streams or waterways that flow all year round. The more vertical distance (head) you have between the point where you take the water and where the turbine is located, the more electricity you can generate.Small scale hydro systems don't usually need water storage. A portion of the stream or river is temporarily diverted through a pipe system to the micro-hydro turbine and generator. It's then returned to the same stream or river. This type of system has far less impact on the environment than large scale hydro schemes.

Implementing Hydropower

Is hydropower right for me?

Consider the following questions to explore the use of micro hydroelectricity for your home or farm. 

  1. Although a total drop (head) of as little as three feet can be utilized for a micro-hydropower system, generally a high volume of flow or a head of at least 10 feet are required for a viable system.

    Yes—Move to question #2
    No—Consider other renewable energy technologies such as wind energy or photovoltaics (PV) for your property.
    Uncertain—Read on to learn more!

  2. Does the water resource have adequate flow? Although low and seasonal (e.g. irrigation) flows can be utilized, the greater the flow the better.

    Yes—Move to question #3
    No—Consult the “Site assessment” module to help better estimate your resources, and if it is too small, then consider other renewable energy sources.
    Uncertain—Read on to learn more!

  3. Do you have the legal right to utilize the water? Under strong Western water laws, simply having water crossing your property does not give the landowner the right to utilize it.

    Yes—Move to question #4
    No—You still may be able to proceed, but you will need to consult your state engineer’s office about obtaining a “non-consumptive” use permit.
    Uncertain—Read on to learn more!

  4. Do you have an electric load within one mile of the resource? The closer the electric load, such as a home or irrigation system, to the hydroelectric resource, the lower the cost and greater the efficiency.

    Yes—Move to question #5
    No—You still may be able to proceed, but you will need to more closely evaluate economic feasibility.
    Uncertain—Read on to learn more.

  5. Are you willing to invest money and some maintenance time into a system to generate electricity for your home, farm, or ranch? Although many micro-hydro systems may present an attractive financial return, especially where they use existing infrastructure such as irrigation civil works, micro-hydropower receives relatively few financial incentives and does require some maintenance.

    Yes—Let’s get started learning more.
    No—Consider lower cost projects such as energy efficiency improvements.
    Uncertain—Read on to learn more!

What are the pros and cons?

Water stored in dams can be turned into electricity in minutes - a process that gives off no greenhouse gases. However, building dams has implications for the environment, economic, social and cultural. Where enough water can be stored, hydroelectricity is reliable and consistent.  However Maryland has relatively small water storage capacity, and water supplies that can vary greatly from year to year. If there is a shortage of rainfall before or during winter, there is a risk of insufficient generation capacity to provide for demand. The growth in wind-powered generation has eased the hydro sector’s concerns about variable water supply - wind supply is more predictable than water supply, making the supply of renewable electricity more predictable and stable. 

What does hydropower cost?

In the right location, micro-hydro has the potential to be a low cost source of renewable energy. The unique nature of each individual hydroelectric resource means that it is difficult to provide estimates for the cost of systems. For example, low-head systems are generally more expensive than more common high-head systems. Also, some landowners may already have the civil works, such as a diversion or penstock already installed for other purposes. A rough estimate of costs is provided in the Table below.  

AC-Direct microhydro system costs installed by a contractor
Component 100 Watt
63 gpm flow
16 ft head
400 Watt
63 gpm flow
80 ft head
3.5 kW
222 gpm flow
163 ft head
Intake $1,200 $1,200 $1,500
Penstock $2,000 $2,000 $4,000
Turbine-generator $2,300 $1,500 $2,500
Controller $350 $350 $650
Transmission line $300 $400 $1,500
Powerhouse $1,500 $1,500 $2,500
Miscellaneous $4,400 $4,500 $4,800
TOTAL EQUIPMENT COST $12,050 $11,450 $17,450
Installation cost $3,000 $3,000 $4,000
Cost per Watt $150.50 $36.13 $6.13
TOTAL COST $15,050 $14,450 $21,450
Geiger, Milton; Sarah Hamlen and Mike Vogel, eds. E3A: Micro-hydropower for the for the Home, Farm, or Ranch, Fact Sheet 3, Steps in the Mycro-hydropower Series. E3A-MH.3. 2015. Estimates provided by Ken Gardner, Gardner Engineering from Kindberg, Leif. Micro-Hydro Power: A Beginners Guide to Design and Installation. National Sustainable Agriculture Information Service. February 2011. Available at http://attra.ncat.org/attra-pub/farm_energy/hydropower.html.

Unfortunately, micro-hydroelectric systems are not eligible for many of the same financial incentives as other renewable energy systems. The federal government provides relatively few incentives for micro-hydro, but local utilities and states may have some incentives. In Maryland, state incentives can include property tax and/or sales tax exemptions. Federal incentives as of 2020 include the following:

  • Renewable Electricity Production Tax Credit–Available to qualified hydroelectric facilities that offer electricity for sale.
  • Under current law, systems need to be in-service by December 31, 2013 to receive a 1.1¢/kWh tax credit for the first 10 years of production. Generally most practical for larger micro-hydro or small hydro installations.
  • USDA Rural Development Rural Energy for America Program (REAP)–Offers 25% grants up to $500,000 and options for guaranteed loans for hydroelectric projects. The program is only available to agricultural producers and small businesses when electricity is not supplied to a residence.

Next Steps

How can I get started with hydropower?

Those interested in developing a renewable or alternative energy on their property should use the following resources as a guide in the development process. In general, the following steps should be taken:

  1. Determine the power capacity of your resource
    • Make sure the waterway is suitable-ideally it will have a good flow of water year round, and enough vertical drop over a small horizontal distance.
    • Ensure the water supply is reliable-compared with wind or solar generation, micro-hydro systems provide a constant flow of electricity (as long as the volume of water flowing remains constant).
  2. Consider economic, lifestyle, and legal impacts from development
    • Check out your rights to the water-you may need a resource consent before using water to generate electricity.
    • You need prior approval to connect micro-hydro to the electricity grid, so contact your utility service and an installer for assistance.
  3. Explore development opportunities and their feasibility
    • Although you may undertake some of the work to install micro-hydro yourself, all electrical work needs to comply with and be certified to appropriate electrical standards. The micro-hydro installation must comply with local regulations.
    • Make allowances for maintenance-of mechanical, electrical and hydraulic equipment. This may only involve a few hours a month. Intake screens need to be kept clear of silt and debris, and collection lakes may require de-silting every few years.

Where can I learn more about hydropower?

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