Winds of Change on the Farm
Published on Tue, 05/17/2011 - 2:13pm
Winds of change - where are they blowing us today? Wind energy is one of the world’s fastest growing energy sources.
Businesses and individuals around the world are looking for renewable energy alternatives to cut costs, meet power needs, and reduce their carbon footprint. We intend to summarize opportunities around small wind energy resources on the farm and provide introductory direction on how to evaluate them.
Wind power has been utilized by man for thousands of years. It is rumored that wind power was used to pump water to the Hanging Gardens of Babylon in the 17th century BC. As early as 300 BC, Persians were using wind power to grind grain, and China was using wind turbines to pump water. In the first century AD, Greek engineers were using a wind driven wheel to power a machine. Windmills started showing up in England in the 11th century. The fictional Don Quixote was tilting at windmills in Spain in the early 1600’s.
By the early 1900’s, as many as six million small wind turbines were installed on farms in the United States. Their primary purpose was to operate water pumps for stock watering and farm home water needs. Additional uses included on-site electricity generation for farm use such as lighting or battery charging, and grinding feed for cattle.
Due to the advent of the 1937 American Rural Electrification Program, operation of wind turbines became less frequent on farms in the latter half of the 20th century. On a related note, in the late 1930’s and early 1940’s Short Elliott Hendrickson Inc. (SEH®) worked with mid-western farmers and other rural customers to connect to the grid during the implementation of this program.
Now in the 21st century, there is an expanded awareness and desire to be as self-sufficient as possible. With federal renewable energy incentives, state funding programs, and private investors, wind power is an attractive, reachable goal not only for corporations and government entities, but also for agricultural producers and land owners. Large wind farms are sprouting up across the nation. And there is a parallel renewed interest in small wind applications at agricultural facilities. This is driven in part by the Sustainability Consortium initiatives which seek, among other things, to reduce energy usage and carbon impacts in the retail food supply chain for companies such as Walmart, Safeway, and others.
This article is devoted to the application of “small wind” on the farm. However, there are significant opportunities for owners of large tracts of agricultural land to generate revenues associated with large wind farms. These opportunities may include participation on wind farm developer teams, or negotiation of lease agreements for use of land. Annual land lease or royalty payments of up to $5,000 per turbine have been reported. Payment will vary depending on location, developer, quality of wind resource, and turbine size. SEH recommends retaining the services of an experienced legal firm to maximize benefits and reduce risks associated with participating in or leasing land to large wind farm developments.
Small Wind Energy Applications
Wind energy can be harnessed via wind turbines and utilized to create mechanical and heat energy for a variety of uses on the farm. Applications may be independent of the grid, used to replace or supplement power from the grid, or utilized to feed power to the grid. Wind energy can also be integrated with other alternative energy sources such as solar photo-voltaic systems, geothermal heat pumps, or small hydro turbines. A comprehensive energy audit of the farm operations is recommended to identify which applications will provide the best value.
There is a large variety of wind-related equipment to support these applications. SEH’s clients have had had good success with using micro-scale wind turbines to produce compressed air. These micro-turbines operate at wind speeds as low as 4 mph and are relatively inexpensive. The compressed air can be used to drive pneumatic pumps, to blow air into pond diffusers for aeration purposes, or to fill compressed air tanks for later use. The Aire-Dynamics micro-turbines (see photo) are relatively compact and can easily be installed by the owner if desired.
Micro-scale wind turbines can also be used to generate electricity for light loads such as lighting, electric fencing, and small pumps and blowers. In many cases, the electricity generated by the turbine is stored in a battery system. There are multitudes of suppliers of micro-wind electricity generator systems as they have popular applications on the farm and on boats.
The opportunities for wind energy usage are both large and small:
• Water pumping for stock ponds or irrigation
• Aeration of stock ponds or wastewater ponds
• Heat and ventilation
• Grinding and mixing
• Compressed air applications
• Remote electric fencing and lighting
• Electrical power production for the farm
On a somewhat larger scale, wind can also be used to replace or supplement electricity for overall farm operations, with the potential to feed excess electricity produced into the grid under a net metering arrangement. Power production may be accomplished by either using one or two large wind turbines, or by using an array of smaller wind turbines (a wind garden). While a single large turbine (with options ranging as high as 1.5 MW) may be able to produce all of the electricity needed for the farm, the owner may be limited by local regulations, height restrictions, and/or need for specialized installation or maintenance equipment. There are several choices for smaller wind turbines that may be distributed across the farm or grouped as a wind garden. WindTamer (see photo) is one such provider of smaller turbines that have good applications on the farm. An energy audit should be conducted first to best determine the appropriate scale of the wind power system. Several other factors also require evaluation before you decide on which wind turbine technology, layout, and equipment provider to move forward with.
Wind Power Considerations
A good understanding of the wind resource is key to determining the viability and best application of the wind resource, as well as selection of wind turbine equipment. Wind activity in your area may vary according to daily, seasonal, and annual patterns (el nino). Dependant on the application, you may want to consider investments in storage systems, supplementary power, or backup power systems. Consider the wind speed range in which the equipment will be operating. Equipment is rated for performance at varying wind speeds, and may not operate effectively at low or high wind speeds.
An energy audit is recommended to define a baseline of where, when, and how much energy is currently being used. The audit should assist the owner in identifying remote applications, potential stranded assets, opportunities to supplement existing systems, needs for backup power, and integration with other alternative energy systems.
Safety is of paramount importance. Safety concerns should be addressed relative to electricity, heat, moving parts (such as wind turbine blades), flying ice off of the blades, and lightning risks. Potential risks of distraction should be considered if the wind turbine is located near a roadway.
Maintenance issues related to the system should also be considered with regard to service frequency, availability of parts, spare parts, accessibility, specialized equipment or service provider needs, and warranty requirements.
Check out the manufacturer’s claims regarding noise and vibrations prior to purchase and selection of the wind turbine location. If the equipment is to be mounted on other existing structures such as silos or rooftops, then vibration effects on those structures should be evaluated. Likewise large wind turbines mounted on pedestal towers may also cause adverse ground vibration intermittently and shadow flicker.
If the wind turbine is to be mounted on a pedestal, evaluate the geotechnical characteristics of the soil in which the foundation will be located. No one wants to see their wind turbine tilting due to unstable soils. This could be dangerous as well.
Consider the potential impacts of the spinning blades on the avian bird and bat population. Depending on the turbine location and height, you will also want to make sure the blades’ spinning area won’t impact other wildlife, livestock, or people for that matter.
If there is intent to provide excess power to the electrical grid via net-metering or other arrangement, confirm the proximity of electrical infrastructure and willingness of the local electrical utility to allow this to occur. The “cost to connect” and net metering or power purchase agreement should be discussed and documented with the accepting utility early in the planning stage. Retain a legal firm experienced in this subject matter to minimize your risk and assist in negotiations with the utility.
There are several considerations with regards to locating the wind turbines, beyond those discussed above, including: interference from other structures and/or trees, building height limits, airspace height limits, visual aesthetics, pesky neighbors, setbacks in local zoning or building codes, and recommended spacing from manufacturers. If the location is near an airport or military base, there may be additional restrictions as large wind turbines may interfere with radar system performance and runway approach glide paths.
The permitting process to site wind turbine projects varies by each location, and becomes more complicated with the size and quantities of wind turbines. It is unlikely that a micro-wind turbine application, such as aerating a pond, would require a permit, but this should be confirmed for the specific location. For large wind turbines, it is very likely there is a permitting process that needs to be followed at each of the local, state, and federal levels. Permitting activities may address zoning, inspections, setbacks, height, visual aesthetics, noise, impacts on wildlife, wetland impacts, and others local considerations. Researching and understanding the potential implications of the permitting process should be conducted early in the process.
Cost evaluations should include short term capital costs as well as long term operating and maintenance costs, avoided power costs, and depending on the project magnitude - potential revenue generation from power sales. The cost evaluation may also include evaluation of other alternatives, positive impact of extending lifetime of other electrical motors and equipment, and potential sales of carbon credits. If the facility is the first link of the supply chain that ultimately ends up with food products in retail outlets such as Walmart or Safeway, consider the intangible value in maintaining that customer base by supporting their sustainability initiatives.
The source of the equipment may play a role in decision making as well. There may be a preference for “made-in-the-USA” equipment. This will need to be documented if funding is related to the American Recovery and Reinvestment Act (ARRA).
There are many potential public-funding sources available to offset costs or provide low interest loans to support implementation of renewable energy at farms. These may vary based on the size of the farm, which state you are located in, and program applicability dates. This information may be obtained by contacting federal, state, and local government agencies and local utilities. Professional service consulting firms can assist with evaluating public funding opportunities on a fee-based arrangement.
Understanding the Site’s Wind Prospects
Understanding the wind dynamics of a particular site is critical to ensure suitable wind speeds are available to meet the overall wind energy project needs. Wind mapping programs and Met (meteorological) towers are two of the most common resources utilized for collecting and analyzing wind data for a particular site.
3TIER is a good example of a mapping program option, which provides accurate, scientifically based wind data for North America, as well as five (5) other continents. The mapping program provides a quick look at the mean annual wind speeds for a specific location (latitude/longitude) at various proposed Hub heights (20 meters (m) to 80m’s), as well as other beneficial data sets.
There are many considerations to keep in mind with regards to application of wind power that include, but are not limited to:
• Wind resource and variability
• Energy audits
• Noise and vibration
• Birds and bats
• Grid infrastructure and the local utility
• Equipment source
• Funding opportunities
Met towers provide continuous wind data [speed (instantaneous, average & gusting wind speeds) and direction], with the use of a wind anemometer. The anemometer can be mounted at various heights, to correspond with proposed wind turbine Hub heights. The data can be collected in short term intervals (eg 15 minutes), with the maximum wind velocity logged as the gust and the overall average wind velocity logged as the average wind speed or mean wind speed over that specific time interval.
For small wind projects (single turbines), mapping programs that use actual wind data and then project that data across the US, provide a generally reliable resource for determining if a wind turbine is feasible for a specific project site. This is particularly true for projects where the individual sitting of wind turbines is not anticipated to adversely affect existing wind patterns from other turbines. Also, an important financial consideration of only using mapping programs to assist with gathering wind data for small wind projects is that the construction of a Met tower could cost as much as 20% of the cost of a small wind turbine. However, in expected low wind velocity areas, both mapping programs and Met towers are recommended to gather the most reliable data available for the site. There may be opportunities to use a modified Met tower where the anemometer is placed on an existing structure (silo, digester…etc) and to gather data for a limited time period (4-6 weeks) at a significantly reduced cost. This will give another data point for determining the anticipated wind energy from a particular site.
In comparison, for large wind farm projects (multiple turbines), where several millions of dollars are being invested, Met towers will most likely be installed to collect on-site actual wind measurements for up to a one year period. The cost of constructing these towers is justified because of both the investment cost of the entire project, as well as the need to make sitting decisions for multiple wind turbines. Certain locations for wind turbines on a project site may adversely interfere with existing wind patterns which can impact other wind turbines on the property.
There are thousands of resources available to aid an interested party to better understand wind energy opportunities. Good starting points include:
• American Wind Energy Association: www.awea.org
• US Department of Energy: www.1.eereenergy.gov/windandhydro
• National Renewable Energy Laboratory: www.nrel.gov/wind
• USDA Rural Development: www.rurdev.usda.gov/or/biz/QuickGuide2mallWind.pdf
• Wind expert Paul Gipe’s website: www.wind-works.org
• Sustainability Consortium: www.sustaiabilityconsortium.org
Collecting the background wind data for a proposed site, whether using mapping programs and/or Met towers, allows the wind turbine designer to better understand what type of turbine will best meet the owner’s project needs. The designer will use the wind data to estimate the amount of energy expected to be produced from the site. Gathering critical wind data and understanding the ultimate project needs will allow an owner/developer team to move from the information gathering process to the decision process. Certainly there are other factors that influence the overall decision to move forward with a project. However, having good reliable wind data from at least two separate sources (mapping programs and Met towers) lends a high degree of confidence to the owner’s project team, especially the project financing arm.
Understanding your Energy Needs – Energy Audits
Performance of a comprehensive energy audit is a key first step to understanding where, when, and how energy is being used on the farm. An energy audit goes beyond a review of the overall utility bills for electricity, natural gas, and other fuels. Specific areas where energy is being utilized will break down into milking operations, heating, cooling, ventilation, lighting, water pumping, manure management, feed handling, and other miscellaneous activities. A detailed audit can be broken down to identify specific energy users including times, peaks, and rates of usage (continuous or sporadic).
The audit enables the owner to identify opportunities for energy efficiency upgrades as well as pinpointing areas where wind energy and other alternative technologies may be utilized to replace or supplement equipment traditionally powered by the grid or petrochemical fuels (natural gas, gasoline, or diesel). Alternative energy applications may be used to extend the lifecycle of other electrical or fueled motors. This allows the owner to make educated decisions about improvement, payback scenarios, and provides a baseline to refer to after making improvements. The documentation can serve as evidence to justify future grant applications and cost-share efforts with public agencies.
Not to be taken lightly, the results of an energy audit can also be used to develop an inventory of greenhouse gases if the producer is tied into the supply chain with Walmart, Safeway, or other retail entities pushing sustainability initiatives.
Further information and assistance can be derived from speaking to state and local government agencies, the state public service commission, and the local public utility. Depending on the complexity and potential risks involved with a project, there are good reasons to retain professional service consulting firms for engineering, planning, and/or legal services.
There are a myriad of opportunities available to utilize wind power on the farm to increase efficiency and energy independence, while reducing impacts to the environment. Likewise there is a large bank of informational and professional resources available to evaluate those opportunities. As discussed, there are many factors to evaluate when making decisions on a wind power project. A wind resource evaluation and energy audit are key tasks to complete early in the process.
In early 2010, Lee Jensen, owner of 5 Star Dairy in northwest Wisconsin, began studying the possibility of enhancing his facility with the addition of a wind turbine for electrical generation. Lee is a motivated and innovative agricultural producer and has already proven to be a leader in utilizing renewable energies. 5 Star Dairy was one of the first farms in Wisconsin that incorporated anaerobic digestion to produce biogas-fueled electricity for the grid. Lee retained the services of SEH to assist him with the evaluation of his site and operations including performance of both a short-term wind resource study, and an energy audit. Next steps will include evaluation of point energy applications for wind power (and other alternative energy options), as well as evaluating the feasibility of developing a wind garden to support power needs for the dairy farm.
If you are curious as to whether or not there is an opportunity for wind power at your location, we encourage you to take a good hard look, whether you are a “do-it yourselfer” or you choose to enlist the services of a professional consulting firm. Keeping in mind what Lee Jensen says, “Our mission is to produce quality milk, profitably and in harmony with nature and each other.” Lee remembers the old windmills on the family farm when he was a kid and is looking forward to exploring this new opportunity to benefit his facility and the environment. Similar to Lee’s memories, these current activities hearken back to the days of SEH’s early roots in working with rural electrification. SEH is working with Lee to enhance his use of renewable energy and complement his current efforts in achieving his mission. We hope this article has likewise helped you to understand how the winds of change are blowing opportunities your way.
Wind Turbine Towers on Your Property
There are a number of questions you should ask yourself prior to sitting a Wind Turbine Tower on your property.
1.Do you have enough wind to economically support a Wind Turbine?
2.Does the topographic layout of your property, including building and structures on site, provide a site for a Wind Turbine/ Tower?
3.What type of Wind Turbine best compliments your site conditions?
4.Do you understand the specific zoning regulations, related to Wind Turbine Towers, which are in place for your parcel of land? Are there any FAA (Federal Aviation Administration) regulations, which need to be addressed?
Towers and turbines are tailored to individual sites. Depending on the size (energy output) of a particular turbine, you have a choice to either place the turbine on a “free standing” lattice or structural steel designed tower or a “guyed steel pipe or steel lattice designed tower”.
Free standing towers - require a smaller footprint of property, due to the lack of need for guy wires. However, they are normally more expensive due to the requirements of the foundation and the structural steel tower composition.
Guyed towers - require more property as the height of the tower increases.
Approximate Guy wire layout dimensions:
Tower Height | Guy Radius | Diagonal Distance | Ginpole Anchor Distance
30 ft. 19ft. 26.8ft. N.A.
104 ft. 60ft. 84.6ft. 29ft.
Generally speaking a lattice or other structural steel type tower designs may allow climbing access to the generator and blade assemblies of the turbine for maintenance. Some small turbines(20 KW or smaller) are mounted on 20 foot structural steel towers; this height of tower provides for easier maintenance, by allowing access with a ladder or a bucket truck.
Guidelines suggest that many small turbines should be placed on a tower that projects at least 30 feet above any other structure (buildings, trees, silos, …etc), within a 300-foot radius of the tower. This type of layout will help reduce/eliminate any turbulences, which may adversely affect the wind turbine performance. Some other turbine manufacturers suggest that their turbines can be mounted directly on top of structures (buildings, silos, digesters…etc) or mounted on shorter towers, as discussed above, without jeopardizing the performance of the turbine.
FAA requires that any tower structure exceeding a height of 200 feet require navigational markings and/or lighting. Normally, small wind turbines are not mounted at heights, which require concern of FAA regulations.
As you consider whether a Wind turbine/tower is appropriate for your needs, please contact a professional to help you assess the pros and cons of various wind turbine/towers available. The professional will assist you by evaluating your site for existing wind conditions and reviewing your site topography/size to determine the available wind turbine/tower systems which will best meet your needs. Please contact Tim Marko, PE, Short Elliott Hendrickson, Inc. (SEH Inc.) with any Wind Turbine/Tower sitting questions you may have. 1-800-472-5881, extension 6240.