Other Renewables
Using Hydropower
in Montana
Hydropower
in Montana
 Harnessing
the energy in falling water is nothing new to Montanans. Early small-scale hydro
projects pumped water for irrigation and mining, turned sawmill blades, and generated
electricity for remote farms, homesteads and factories. On a larger scale, beginning
in the late 1800s, dams built on the Missouri River supplied power to hoist ore
from mine shafts, to compress air for lead and copper smelters and to power electric
lights for growing cities. Although most large-scale sites have now been developed,
the small-scale hydro potential of the state's many rivers and streams is still
untapped. Small-scale hydro includes projects with a generating capacity between
100 kilowatts and 1 or 2 megawatts; micro-hydro projects are systems having power
outputs of less than 100 kilowatts.
If you're thinking of starting a small hydropower project, here are some basics.
Accessibility to the Land
Although most project developers
own the land on which the project will be located, others must those rights from
landowners. The system intake may have to be located on land owned by a state
or federal agency or by another private party. In other cases, both intake and
powerhouse may sit on the project developer's land, but the penstock that connects
them might cross another person's property.
The feasibility of an entire project should be determined before any purchase
or lease agreements are arranged. Also, if it is known that the property in question
is not available under any circumstance, alternate plans should be considered.
Determining Site Potential
In order to determine the hydro
potential of a site, information regarding amount and variation of streamflow
is essential. You should find out if streamflow records have been kept for the
stream at any time. A good place to begin inquiries is with the U.S. Geological
Survey (USGS), website
under "Water Resources," where you'll find realtime streamflow data
and historical streamflow data, including lists of active and discontinued stations.
If historic flow records are not
available, you should immediately begin monitoring the streamflow at the site:
the feasibility of constructing a small power plant is dependent on exactly how
much power your stream will put out. The two most important factors to consider
are flow and head.
Flow is the quantity of water flowing past a point at any given time. This amount
varies both seasonally and annually, so it is important to collect accurate data
for each season of a full year. These data should then be compared to USGS information
from your area to decide if it was a dry year or a wet year. You can obtain snow
pack information for your area at the U.S. Department of Agriculture
Natural Resources Conservation Service in Montana
Minimum flow rates are necessary
to accurately assess the minimum continuous power output you can expect from your
hydro unit. Also, maximum flow estimate is needed to ensure that your structure
will withstand peak flooding.
Head is the vertical distance in
feet from the surface of the supply water to where the water leaves the turbine.
The head exerts pressure that can be turned into usable power, so the greater
distance the water falls, the more energy is available.
Low head is considered to be less than 60 feet; high head is 60 feet or more.
Although there are exceptions, 10 feet of head is usually the minimum necessary
to generate power.
Once you have determined the net
head and the average flow rate for your site, you can calculate the power output
from your stream.
Determining Energy Needs
A central question to project feasibility
is whether or not the site will produce enough power to meet your energy needs.
Two types of energy estimates should be evaluated - peak demand and total consumption.
Peak demand is the maximum power needed at any one time. In household use peak
demand occurs when all electric loads are on at once. Total consumption is the
number of kilowatt-hours used in a given period. Utility companies usually use
the measure kilowatt-hours per month.
A system capable of meeting total consumption will not necessarily cover peak
power needs; consumption or power needs may have to be adjusted. If your power
needs are greater than your potential energy source, you may consider storing
electricity in batteries or buying extra electricity from a utility to supply
peak demand needs. Contact your nearest Montana utility to seek assistance early
in the process. (utility page link)
Another good place to find information on determining stream head and flow, calculating
the power output of your stream is
Solar Plexus in Missoula.
Water wheels and water turbines are two basic types of hydropower machines. Water
wheels are the traditional devices used to convert the energy in flowing and falling
water into mechanical power. They are used in grinding grain, and operating saws,
lathes, drill presses, and pumps. Usually large in diameter and slow turning,
water wheels work well in streams with large variations in stream flow. Trash
racks and screens are usually not needed because sticks, stones, and dirt will
flow over the wheel in the stream of water. Water wheels can be used to produce
electricity, although the large diameter and slow rotation requires the rotational
shaft to be geared up to a much higher RPM.
Because water wheels operate at slow speeds, they are considerably less efficient
than water turbines in producing electricity. Water wheels are also bulky and
in harsher climates have to be housed in large structures to avoid ice buildup
in the winter.
Water turbines spin at high speeds, are used for electrical generation and can
be as high as 70 percent - 80 percent efficient in producing mechanical or electrical
energy. While water wheels use water carried in an open flume or channel, turbines
receive their energy from water carried in pressure conduits. Water turbines are
complicated pieces of equipment and must be carefully installed.
Also, debris such as rocks, sticks and sand can interfere with the blades, so
a trash rack or screen is required to prevent this material from going through
the turbine.
System Components
A typical micro-hydro system consists
of several components. An intake structure controls the flow of diversion water
to be used. A penstock, or flume, carries the water from the intake structure
to the turbine. The powerhouse contains the water turbine, generator and controls.
Calculating Costs
Once the head, flow and system
output are known, you can contact equipment suppliers to get accurate cost data.
There is no point in contacting these people before the site details are known,
as costs of equipment would vary considerably with different sites.
Costs vary widely with each site and size of system.
Environmental Considerations
Water wheels and water turbines
alone have a negligible effect on the environment. Most hydro systems, however,
require a dam to ensure a continuous source of water. Damming a river or stream
can have a long-term effect on the environment surrounding the site. Streamflow
is changed, and the water table is usually raised behind the dam and lowered downstream
from the structure. You are creating a pond or lake where a stream ecosystem used
to exist, so silt may accumulate and you may have constructed an ideal breeding
ground for mosquitoes.
Fish movement may be blocked if a fish ladder isn't used. Access roads may contribute
to erosion and disrupt the landscape. In general, the larger the dam, the greater
the impact on the environment. If you foresee the ecological impact of installing
a hydroplant, you can keep stream disruption to an absolute minimum. Keep in mind
that you may have to radically change your design to work with your local ecosystem
or, in some cases, abandon the hydropower project completely.
Permitting and Licensing
Before you do any construction on your stream, you should be aware of the regulatory
conflicts you may face. A variety of institutional and legal barriers exist and
your project will go much smoother if these potential problems are identified
early in the schedule so you can take the required actions.
Although numerous agencies have potential permitting or review authority, small
hydropower projects are likely to require only a few permits. Nevertheless, the
time required for obtaining all permits and licenses may be a major part of the
project duration, so it is important for you to begin the permitting process in
the early stages of developing your site.
Local Permitting Requirements
First of all, you should contact
local government offices to determine local permit requirements. The local city
and county planning and public works departments can tell you which permits are
needed. All local permits or requirements must be satisfied before federal hydropower
licenses will be issued. Generating facilities affecting only the developer's
property should encounter few problems.
State Permitting Requirements
A hydropower developer in Montana will have to obtain a number of permits. The
best source for information on those permits is the Montana Department of Environmental
Quality.
Check "Water
Quality Laws and Administrative Rules" and "Water
Quality Discharge Permits."
|
