The Dairy Waste Dilemma

Today’s typical large dairy farm operation has little resemblance to that of 30 years ago. Back then, a herd of 200 animals was considered a very large operation, and herds of 20 or 30 cows were the norm. Today there are many fewer operating dairy farms, but they are on average much larger. Typical sizes vary around the country, but herds ranging in size from 300 to 600 animals are common, and operations many times that size are no longer unusual. A dairy herd of 1,500 cows, or even several thousand cows, doesn’t make the news anymore. According to agricultural economists, this trend is not likely to change any time soon.

Herd Size is Growing Dramatically

The reasons for this growth in herd size are multiple, and include the availability of equipment, the cost of land, and the need for very specialized skills to produce milk that meets modern standards. The fact is that these larger, more specialized dairy farms are appearing everywhere. Many contract out for feed, for raising of the calves, and of course for labor. A herd of 2,000 cows milked three times a day may require a staff of 20 to 30 workers. The dairy farm that produces its own feed and is operated exclusively with family labor is becoming less common.

Are There Limits to Growth?

Most of the constraints to growth of the dairy farm have been overcome. Modern herd management, sophisticated milking equipment and contracting for feed and labor have removed many of the limits to growth -- with one exception. We’ve discovered that the primary limit to growth is often the ability to dispose of animal waste in a way that meets environmental standards and maintains community acceptance. This challenge is particularly important in areas with significant annual rainfall or for those that are located in proximity to other rural or suburban residences. In these areas, the ability to expand from “traditional” herd sizes of 60-100 animals to large production operations has been constrained.

Traditional Manure Technology

In traditional operations, livestock manure was collected, stored and spread on the surrounding land periodically. The volume of manure was moderate and it didn’t need to be carried too far from the barn. This approach is normally not acceptable in a large scale dairy farm.  It simply requires too much land, too much energy, and may result in levels of odors that are objectionable to surrounding landowners. Further, it can result in environmental problems from runoff of nutrients into adjacent watercourses.

Digesters Can Solve Problem

Part of the solution is a manure digester. These come in many designs, but the basic premise is to break the manure down biologically into solid, liquid and gas components. Done right, a digester virtually eliminates odor complaints by neighbors and hostility by local officials and regulators. The resulting low-pathogen solids can be dried and used as livestock bedding. The liquid can be piped to the point of use and knifed into the ground in a very low-odor operation. And the gas (biogas) can be refined into Renewable Natural Gas.

Getting Value from a Digester

A digester is a major investment, and owners are attracted to the idea of maximizing the value of the outputs to help offset the expense. An early approach has been to use the output biogas directly to operate a reciprocating engine generator set. The owner can use the generated energy on the farm and sell the surplus to the electric utility. This has been done with some success in some areas. The problem is that electric utilities typically pay only their “avoided cost” for the energy, not the retail or even the wholesale rate. In effect, the dairy farmer is competing with the utilities’ very large and efficient nuclear and coal-fired plants.

A Better Way

Agri-Waste Energy has found an alternative way of using this digester output. That is to install systems that refine it to the quality of pipeline natural gas and market this “green” Renewable Natural Gas product to industry. The gas can be shipped either in compressed form in tanker trucks, or can be injected into the pipelines operated by common carrier gas transportation companies. In this way, the farm can get a full, fair value for the energy it produces.

First Phase Completed

We have worked with Emerald Dairy near Baldwin, Wisconsin to install the first digester and biogas refinery (Gas Cleanup Facility) system. This method of getting full value for digester biogas is getting attention across the country, and we are seeing many very serious expressions of interest.