Feasibility of Reducing a Dairy Farm’s Manure Enterprise Costs Using a Wet Gasification Technology

Manure management is a major system on dairy farms, and there is a goal to minimize costs and maximize benefits. Technology that would reduce the mass of the manure to be spread, produce energy and a potential by-product for off-farm sales is needed. Adding wet gasification technology to existing manure systems with the goals of reduced spreading costs and possibly increased by-product sales was evaluated on a central New York farm that was considering expanding.  For expansion to be possible, additional cropland was needed to recycle the additional manure at a further distance from the farmstead. An economic analysis examining the potential impact the wet gasification technology would have on the farm was conducted and results were shared with the dairy producer for use in making informed decisions.

What did we do?

A wet gasification technology that was presented by the manufacturer to be able to extract energy from manure solids (also reducing mass) was evaluated to determine the potential as an improvement to the farm’s existing manure management system. Application of this technology on an example farm was investigated to see what the applications might be on the existing farm (1,500 cows and 1,590 acres) and when expanded to 2,500 cows with 2,990 acres of cropland. Current and projected farm data along with cost and performance data from the manufacturer of the gasification system were used to perform an annual economic cost-benefit analysis as a way to determine the value of the system to the farm’s manure management enterprise.

Example mass and energy flows for a wet gasification system.

What have we learned?

There are many variables to consider, and the results of the sensitivity analysis show that the variables that influence the outcome of the total annual economic cost-benefit analysis are the ones least under the control of the technology provider or farm (capital cost, lost capital rate, milk production change due to bedding use change, nitrogen value of fertilizer, price of electricity, and value of the ash). Annual spreading costs at the time of analysis ranged from $36/acre for close fields with a low amount of manure spread, to $256/acre for further fields spread at a high amount of manure.

For the case farm analyzed, the system economics would only be favorable if optimistic values were assumed for some of the predictor variables such as high prices for the ash by-product and/or higher prices for the excess energy produced. Raw dairy manure’s moisture content is too high for efficient gasification. Wet gasification is better suited to operations where the raw manure has lower moisture content (due to substantial bedding use) or can be pre-processed to obtain  a very dilute liquid stream (that can be spray irrigated) and a solid product, having 25-30% solids, that could be processed by gasification to produce a salable ash. The values for byproducts, energy and nutrients from manure, need to be large enough to support a manure treatment system. Dairy farms need to consider the impact of a manure treatment technology on the whole farm system.

Prices to obtain a zero economic benefit (net benefits minus costs equal $0) for the expanded 2,500-cow dairy in central NY for each variable alone.
Variable Break-Even Price Comments
Capital costs ($/Unit) $0 Wet Gasification

$0 for SLS

$1,750/kW for steam gen set

Assuming grants are available

Assuming a separator already exists

Steam gen-set is $1,750/kW

Electric Price ($/kWh) $0.156/kWh

5M kWh/yr. produced

Includes $0.03/kWh maintenance cost on engine generators. (This is renewable energy but only ~50% reduction in GHG
Hauling cost ($/load) $2,530/load

159 loads/yr. reduced

8,400 gallons/load (approximately a 420-mile round trip)
Ash Sales ($/ton) $374/ton

898 tons/yr. produced

This price includes the reduced hauling costs as the water separated from the ash can be spray irrigated without hauling.

Future Plans

We continue to evaluate manure treatment systems that have the potential to reduce the mass of the manure to be spread, produce energy, partition the nutrients, reduce greenhouse gas emissions, and a produce a potential by-product for off-farm sales and extending this knowledge to dairy operators.

Corresponding author, title, and affiliation      

Peter Wright, Agricultural Engineer, Dept. of Animal Science, Cornell University

Pew2@cornell.edu

Other authors   

Curt Gooch, Senior Extension Associate at Cornell University, Dept. of Animal Science, PRO-DAIRY

Additional information               

Additional project information can be found on the dairy environmental system webpage: www.manuremanagement.cornell.edu.

Acknowledgements

The farm and the wet gasification technology company provided the needed data to make the economic analysis. Funding for this project was supported by Cornell’s Jumpstart program.

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