by Sanne Kure-Jensen
Farm inputs can include energy in the form of fuels, electricity and fertilizers. Crop and livestock production uses energy in many forms. Energy heats water for washing equipment and harvested crops, and powers lighting for production and handling areas. Livestock and produce producers use energy for heating, ventilation and refrigeration. Transportation uses more energy to move inputs to farms as well as moving produce and livestock from farms to processors, markets and consumers. Sustainable, viable farms maximize energy efficiency and minimize costs for all aspects of production.
The Natural Resource Conservation Service (NRCS) oversees programs that help farmers and producers conserve energy through a variety of on-farm energy upgrades for existing buildings. Kip Pheil, C.E.M., Acting Leader of the USDA NRCS National Energy Technology Development Team and Stephen Henry, P.E., NRCS South Carolina Assistant State Conservation Engineer described NRCS programs and shared their expertise in a webinar called “Key NRCS Energy Practices: Farmstead Energy, Lighting, and Building Envelope.”
Pheil described typical farm inputs quoting a study by John Miranowski. Typical farm inputs and costs include over 20 percent electricity, nearly 30 percent diesel fuel, nearly 10 percent gasoline, nearly 10 percent gas (shared between LP and natural gas) and nearly 35 percent between fertilizers and pesticides.
No two farms have identical conditions, challenges or opportunities. On-farm audits made by qualified auditors may locate potential energy saving measures. These energy efficiency improvements may be opportunities for NCRS cost sharing partnerships.
According to Henry, energy audits must thoroughly document existing farm building conditions. Be sure to list current and potential future uses (livestock, greenhouse, processing, storage, etc.). Complete descriptions of lighting, heating and ventilation systems, as well as the building envelope or shell should be included. Baseline documents should contain equipment specifications, lighting fixture layout, site plans and annual energy expenses. NRCS energy programs can help pay for on-farm energy audits done by qualified NRCS Technical Service Providers (TSPs). Their audits should comply with NRCS and American Society of Agricultural and Biological Engineers (ASABE) standards including S612. Occasionally, S612-compliant audits completed by non-TSPs can be used to support an NRCS contract to implement energy improvements.
Energy auditors can compare a farm’s Energy Use Index (EUI) to regional and national data. EUIs are based on farm enterprise research and measure the typical energy needed per unit produced — for example, producing a gallon of syrup or 100-weight of milk. Variances from typical EUIs may demonstrate opportunities for improvement. Equipment upgrade recommendations may or may not include recommendations for Energy Star rated equipment or lighting. Not all farm equipment has been rated against the Energy Star standards.
Henry said buildings with climate control systems for heating and/or cooling for any part of the year should have these systems included in their energy audits. Livestock type and numbers for different times of the year, equipment specifications, conduit or duct diagrams and building insulation data may be included. U-values measure the rate of heat loss or transfer through the building envelope: walls, doors, windows, ceiling and roof. Low numbers typically indicate good insulation and heat retention in cold weather.
In the Farm Energy webinar, Pheil explained that heat always moves from warm to cool materials or areas. Conductive heating happens when heat moves between solid materials in contact with one another like water to pipes. Refrigeration takes advantage of convection between fluids (liquid and/or gas). Radiant heat transfer does not require materials or contact; it can happen in a vacuum.
Henry reminded farmers and farm system designers that when changing from incandescent lighting to florescent or other high efficiency lighting systems, be sure to consider the loss of heat produced by those old bulbs. Therefore, heating and cooling systems may need adjustment. Examples include incandescent lamps used as heat lamps for livestock or in a pump house. Recommendations for new lighting systems in cold climates may include recommendations to insulate barn walls as well as upgrade summer ventilation fans and control systems.
Pheil said, “The main consideration in an energy analysis is to account for increased heating system or decreased cooling / fan system run-times if a lighting system upgrade causes a large shift in heat output.” Pheil said in his experience, “the heating penalty is offset by the cooling benefit so I ignore both which also usually works.”
Energy audits and return on investment calculations may justify implementation of equipment upgrades or system replacements. Farmers and system designers should review implementation plans and ASABE Standard S612 to ensure designs have considered the whole farm and all activities planned in that space before installing new systems. Another important consideration when replacing energy systems is proper disposal of the old system components. When removing aluminum or copper wiring, consider recycling the metals. Failed fluorescent light bulbs, many older fluorescent ballasts, old refrigeration compressors or round, mercury thermostats need proper disposal at designated sites.
Farm energy efficiency
by Sanne Kure-Jensen