The Mission Critical Dairy Farm
Many modern dairy farms are complex businesses involving high and low-tech equipment, veterinary medicine, animal husbandry, land, facilities and building management, transportation, product production facilities, commodity sales and purchases, animal waste disposal, and other environmental issues.
Dairy farming is a major industry. The 2007 Department of Agriculture census (www.agcensus.usda.gov) counted 70,000 dairy farms, including operations from major farms to residential and retirement farms, with total sales of $35 billion. Power outages expose dairy farms to significant hazards, and the rural location of many farms makes them particularly vulnerable to these outages.
A reliable power supply is necessary to operate feeding and watering equipment, lighting, fans, heaters, and specialized equipment such as milking machines, refrigeration and milk processing units, and water pumps for sprinkler and emergency fire usage. Backup generation (which can include co-generation) is key to maintaining a power supply for these functions at all times. Dairy farms are often located in rural areas, which put them at greater risk for power outages, so their operators should be prepared. Utilities may also assign rural areas a low priority for restoration of power supply following a disaster. It is highly possible that a severe winter storm or disaster could isolate a farm for one or two weeks or even longer.
In 1998, an ice storm in the northeastern U.S. downed power lines throughout the region and showed that the most critical agricultural need was for electrical generators. Since electricity is necessary to operate milking equipment, loss of power makes it extremely difficult or impossible to milk cows. Farmers who had adequate-sized generators and who knew how to operate them were soon able to resume milking their cows. Farmers lacking generators or having generators that were inoperative or failed due to poor maintenance, insufficient fuel on hand (since deliveries were problematic), or operator incompetence faced disastrous consequences. Not being able to milk the cows caused great production losses. Worse, cows became ill and, in some cases, died.
Snowstorms, particularly those with high drifts, can also cause outages, sometimes inadvertently caused by the farmer. A farmer digging his way through a snowdrift with his tractor might inadvertently hit a utility pole causing the power cables to break, leaving the farm without power. Drifting snow in a blizzard can also inhibit a farmer’s ability to generate electricity. Snowdrifts can block access to generator enclosures or buildings. Proper construction and spacing of buildings is the only way to prevent snowdrifts from blocking access to equipment housed on a farm.
Heat, too, can bring its own problems. Periods of intense heat and humidity during August 1977 in California and July 1995 in Iowa and Nebraska and caused the loss of 725 cows. Very high heat or adverse combinations of high ambient temperature and humidity can cause heat stress in cows when there is little air movement or cloud cover. These conditions can cause high mortality rates in animals.
Sprinkler systems can reduce heat stress, and some farmers also install fans that run alternately with the sprinklers because dairy cattle may suffer heat stress while being herded. The goal is to wet the cow with sufficient water to evaporate and reduce the surface heat. During heat waves, the excessive drain on power supplies can lead to power black outs making on-site generation a critical necessity for this application.
Planning for power outages is essential on dairy farms. A dairy farmer should prepare for a few days or, worst case, even a few weeks without power, lights, water, heating, or equipment operations. A gen set with sufficient power output is the best mitigation for electric power failure on a farm. The local electric utility or Cooperative Extension should be able to provide information about the farm’s load requirements, the proper sizing of the generator, fuel storage requirements and sources, costs of generators, and hook up procedures. The veterinarian can also be a valuable source of information regarding critical energy supply needs of dairy cows during an emergency. Dairy veterinarians can assist dairy farmers in identifying risks and preparing emergency plans.
There is more to it than merely installing a generator. During a howling snowstorm the power may go out. The farmer must make his way to the generator building, but it has been over a year since he has used it and his flashlight provides limited illumination. There is gas in the tank, and the starter motor cranks slowly, but the generator fails to start. This is not an ideal time for engine failure diagnoses and repair.
Since farmers have experience in repairing engines, the farmer in this tale may manage to start this unit after working on it for a while At that point, if the unit is not hooked up, he may be unsure of the proper safety procedures to hook up the generator. There are real risks if the farmer hooks up a generator before disconnecting the farm from the power grid to prevent power from being sent back into the power grid. Power reversal is a concern of every utility and has led to several deaths and damage to equipment after disasters. Electrical wiring involved in the installation of a generator must meet appropriate safety standards and should be installed by a certified electrician. Farmers should familiarize themselves with the proper operation of generator equipment and be familiar with the procedures to be followed in the case of an electrical outage. In addition, generator equipment should be inspected and tested on a regular basis.
As an alternative to generation used solely for emergency purposes, and as a means of supplement dairy income while mitigating the environmental impacts of farms, some dairy farms are implementing renewable energy plans to turn cow manure into electrical energy. Such systems make economical use of cow manure from the farm and provide a reliable source of on-site generation of electricity. Cow manure is used as a source of methane, which can be used as a fuel for engines that drive generators to make electricity. Instead of being spread on cropland, a dairy’s manure goes into a digester that produces methane gas to fuel engines that power generators capable of producing a constant flow of kilowatts sufficient to satisfy the farm’s needs. The “waste” heat from the engines’ exhaust is captured and used to warm water that can be used for the operation of certain types of anaerobic digesters in addition to other hot water needs of the dairy such as heating and cleaning. The process is part of cogeneration, the production of heat and power, which makes the engines extremely efficient. The excess power can be sold to the local electric utility. Cogeneration units can provide reliable electrical energy for prime or peak-shaving use, as well as emergency stand-by power. It is necessary to arrange with the local electric distribution utility for the cogeneration unit to be interconnected and for any sale of renewable power (or biomethane).
The Federal Emergency Management Agency (FEMA) offers a course “Livestock in Disasters” addressing farm hazards and how to mitigate and respond to these hazards. Information derived from that course was used for the purposes of this article.