Solar, Wind Power

Solar-powered water pumping in the Northeast

Solar has had a difficult time in the northeastern United States, due to the old notion that there is not enough sunlight in the region as well as the relatively high, up-front cost of installation. This concept is slowly disappearing as costs decline and the value for grid-tied photovoltaic (PV) systems is being realized in terms of peak-shaving and power reliability. However, some of the best opportunities for PV are off-grid, where extending the utility wires is prohibitively expensive. One of the greatest applications for off-grid PV is for pumping water, particularly for livestock. Solar water pumps have proven to be a cost-effective and dependable method for providing water to grazing livestock in remote parts of the western United States as well as in many other countries. My colleagues and I have found that in the rural areas of the northeastern United States, solar water pumping works and provides all the environmental benefits of renewable energy as well as the potential to keep waterways clean.

RE Insider, February 9, 2004 – Livestock grazing is a mixed environmental bag. Overgrazing can lead to severe environmental damage, such as soil loss and pollution of surface and groundwater supplies. On the other hand, well managed grazing can be an environmentally sustainable and economical practice of raising livestock for milk or meat. For instance, grazing dairy cows, which is employed by many organic farmers in the northeastern states, is an alternative to confined feedlot systems where all of the food and water is brought to the animals. In grazing, one of the limiting factors is the availability of clean water. For a dairy farmer, it is simple: limited or poor accessibility to water leads to a reduction in milk production. Every farm is different in terms of land and water resources. Some grazing farmers have available surface water as either ponds, developed springs (a hole in the ground), or streams. However, it is against best practices to allow animals to drink directly from these sources, which can pollute the water and reduce the health and cleanliness of the animal. The water source should be fenced off and water should be pumped to a nearby stock tank. Other farmers rely on wells to provide water, which requires pumping to lift and distribute the water into the fields. In either case, if these water sources are far from the power lines, solar-powered pumps can be the most economical and least labor intensive choice compared to windmills, gas- or diesel-powered generators, and hauling water. But is this true for the northeastern states? Theoretically, the answer is yes because grazing in the northeast is seasonal (there is obviously none in the winter) and PV pumps work best when you need it most: hot sunny days when the animals need more water. My colleagues and I tested this by installing a submersible pump in a well and a floating pump on a pond at a farm in rural western New York. The power for each pump comes from a pair of PV panels mounted on passive solar trackers that point the panels directly at the sun throughout the day. Both provide water to adjacent stock tanks with float switches that turn off the power when full. There are no batteries on these systems. Larger stock tanks are used to store water as an alternative to storing power in expensive batteries. A network of pipes can be used to distribute water from a main reservoir. After three years of use, I can say that the systems worked as advertised. The submersible pump, rated at 1.9 gallons per minute, pumped an average 830 gallons per day in the summer and almost 600 gallons per day in the fall. This was done with essentially no labor during the season. In fact, the key to solar’s success is the low labor and maintenance costs relative to the other options. They are easy to install and the systems can be modular and the base system can be configured for a variety of environment-specific needs. One of the main drivers of the success of these systems is the availability of pumps and electronic controls specifically designed for use with PV. Windy Dankoff, one of the pioneers of solar water pumping and the founder of Dankoff Solar Products, says, “Solar pumps use special design in all aspects, to work at high efficiency from a varying power source. This eliminates the need for batteries when the pump is used to fill a storage tank. Recent developments have made solar pumps economical, simple and reliable. In some cases even the initial cost is competitive with generator-powered systems.” Compared to using fossil fuel-powered pumps or hauling water, the PV pumps are much easier on the environment in two direct ways. First, they emit no gases associated with air pollution or global warming, and there is no fuel or oil to spill. The other environmental benefit occurs when these pumps are used to replace direct access of animals into ponds and streams. Studies have shown that direct cattle access to waterways can cause increased erosion of stream banks and lead to contamination of surface and groundwater with sediment, bacteria, and nutrients. Keeping animals out of the water and allowing them to drink from tanks will severely reduce water pollution. This practice is good for cows too because clean water and no mud on the hide makes a healthier cow, which increases the economic benefit for the farmer. In summary, these pumping systems fit well into animal grazing operations due to several advantages, including: – Low maintenance – Working best when you need water most ý when the sun is shining in the summer. – The ability to make a mobile system that can be moved to different pastures. – A range of pump types and power outputs to enable the design of a system for any application. – No fuel and no emissions – The potential for reduced water contamination. State governments that are interested in supporting small, grazing operations and want to reduce animal-caused water pollution can provide incentives for solar water systems. It could be a small investment with long-term benefits. About the author… Chris Sinton is a private consultant based in Middlebury, Vermont. He specializes in renewable energy technologies and materials processing for the glass and ceramic industries. He has been involved in research and demonstration projects in solar, wind, and biomass. As the former director of the Center for Environmental and Energy Research at Alfred University (Alfred, New York) he managed grants from the US-EPA, US-DOE, and the NYS Energy Research and Development Authority that funded research projects including hydrogen storage, fuel cells, recycled/waste materials, and biomass gasification. He holds a Ph.D. from Oregon State University. This article previously ran in Energy Central’s Energy Pulse column.