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Cattle turn forage into beef, but only if they have adequate water. Since the late 1800s ranchers have relied on mechanical windmills to capture the wind and use its power to pump underground water to the surface, lifting water from the well like a straw in a glass. In recent years, innovators have used solar panels to harness the energy of the sun and produce electricity to run a pump to pull the water from the ground.

"If electricity is readily available, then an electric pump may be the most cost-effective option," says Carl Homeyer, state agriculture economist for the USDA Natural Resources Conservation Service (NRCS), Temple.

"Remote pumping, whether it's solar-powered or wind-generated, is worth considering whenever the distance from the utility grid exceeds about one-half mile." Utility extensions can commonly cost $10,000 to $30,000 or more per mile, making alternatives economically feasible.

Producers who are considering a remote watering system, regardless of the power source, should start with a basic list of questions.

1. How deep is the well?
Knowing the depth of the well and the depth to water is critical to sizing the pump, Homeyer says. Solar pumps are available in many flow rates from 1 gallon/minute to 80 gallons/minute. For livestock applications, 3 to 4 gallons/minute may be sufficient.

Another factor to consider is some solar pumps are variable, meaning by increasing solar panels you increase flow rate. This allows producers to compensate for deeper well depths, but raises the cost of the system, he says.

In general, mechanical windmills and solar pumps are best for small quantities of water and low pumping heads, Homeyer says. Head is the elevation difference between the water and the tank.

If producers are seeking a large-scale livestock watering application, wind-powered electric systems, which use the wind to power submersible pumps, may offer an alternative. According to information from The Samuel Roberts Noble Foundation, the system is more efficient over a wide range of wind speeds and requires less maintenance than a traditional windmill. With that said, they are an expensive technology and may be cost-prohibitive in many situations.

2. How far will the water need to be pumped and what is the elevation gain?
Some solar pumps are designed to pump into a pressure tank, giving producers the ability to move water to other remote areas, Homeyer says. Another advantage is that storage tanks can be equipped with a float and cut-off switch to allow the pump to operate only when water is needed.

3. How much water will need to be available and at what flow rate?
While the amount of water cattle consume each day depends on their size and the weather conditions, 25 gallons per head per day with a 3- to 7-day storage capability is the general rule of thumb, Homeyer says. Even though every animal will not drink at the same time, a 100-cow herd would need about 10,000 gallons of storage. Additional allowances may need to be made for wildlife if this is a remote watering facility, he says.

4. Will the water system be in use in the summer when demand is highest, in the winter, or year-round?
In the summer, sunshine is plentiful, and the wind blows less, Homeyer says. In the winter, the days are shorter, the sunshine is less intense, but the wind is more constant.

If a system is going to be used through the cold months, producers need to take precautions to prevent the water from freezing in the lines, creating a blockage and inadvertently burning out the pump, Homeyer says. Mechanical windmills are equipped with a wooden pump rod that acts as a shear pin to protect the windmill from damage. If winter winds restart a windmill with ice in its lines, the wooden rod shatters and prevents damage to any of the main pump parts.

5. What are the maintenance requirements?
Solar-powered watering systems generally have a higher initial cost, but require less maintenance and upkeep than mechanical windmills, Homeyer says.

Some ranchers have found that solar-powered systems generate great savings in labor and fuel costs. On a ranch in Wyoming, as reported in the Wyoming Livestock Roundup, management had a man who did nothing but check windmills 8 hours a day. Since the ranch replaced its mechanical windmills with solar-powered watering systems, the man now checks them every 3 days.

If groundwater has significant levels of suspended solids, this can cause wear on submerged electric pumps and valves, Homeyer says. Windmills and their pump systems are not as prone to damage from poor water quality.

6. What is the backup plan?
Because both windmills and solar-powered systems have periods of low production, it is important that the water system include enough storage to provide a backup supply for 3 to 7 days, Homeyer says.

In the case of the solar-powered system, it is more efficient and generally more economical to create storage than to install and operate a generator, he says.

7. What is the cost of each system?
A solar-powered submersible pump with solar panels capable of drawing water from depths greater than 400 feet may be available for approximately $8,000. New windmills may range from $5,000 to $10,000.

"Remote watering systems are not 1-size-fits-all," Homeyer says. "Each alternative has to be considered in the context of an individual ranch and an individual situation. Unless the producer has experience designing these systems, it's a good idea to contact the experts and get their ideas. Legitimate businesses should provide a design and a cost estimate that will allow producers to not only determine the expense, but the applicability to their operation."

Editor's Note: This is the fifth in a 12-part series focusing on using partial budgets to answer questions in a technique commonly known as "penciling it out." Because Texas and Oklahoma are so diverse and each ranch is unique, the series was not designed to provide a 1-size-fits-all answer. Instead it was created to help producers become familiar with a handy tool that can be used to strengthen the bottom line. The series has been developed in collaboration with Carl Homeyer, state ag economist for the USDA NRCS. Homeyer earned his bachelor's degree in range science and his master's degree in land economics and real estate from Texas A&M University. Before joining the NRCS in 2009, Homeyer operated his family's Burleson County ranch, which also includes broiler houses, while owning and running several small businesses.

"Solar Pumps vs. Windmills" is from the May 2013 issue of The Cattleman magazine.