Matt Smith, PhD Student in Natural Resources and Dr. John Aber Financial support from Hatch NH00605 and

An Integrated System to Provide Bedding, Composting and Energy Woodlands Bedded Pack Heat Recovery Compost Wood Shavings Compost back to Farm Fields

Facility donated to UNH by private donor with supplemental support from NH Agricultural Experiment Station Primary goal is to increase heat production, extraction and use. The heat will be used to supply hot water in the milk house Facility is only the 4 th in the world using this technology. Uses Agrilab Technologies Isobar Heat Pipe technology (fancy name for a giant heat exchanger)

Aerated Static Pile – type of composting where material is not turned – aerated by fan blower system instead Heat is produced by metabolic activity of aerobic microbes Larger microbial population = more heat Providing a favorable microbial environment is #1 goal for compost quality and heat recovery

1. Blower pulls air through compost 2. Hot, moist air passes over isobars heat captured in phase change to gas in isobars 3. Heat transferred to bulk water tank as phase change back to liquid in isobars 4. Hot water used for all hot water needs in milk house How the System Works

Unload old compost material and vacuum out aeration lines Cover aeration lines with 12’’ of bole wood chips

Compost loaded, mixed and unloaded using manure spreader 2 bays loaded per monthly batch (1 bay serves as control, while other is manipulated 215 yd 3 (100 wet ton) max load per batch 12 hrs. of labor to unload/load a batch (time req. continually dropping)

As oxygen is drawn through the pile from the aeration system, hot compost vapor is pulled out of the pile and into the pipes. Aeration for heat removal can be 10x the requirement of oxygen demand from the microbes (Rynk 1992) Compost vapor contains Tremendous thermal energy CO 2 NH 3

Goal is to reach 160 F for pathogen kill, but to maintain in the for majority of batch duration Temps > 170F are lowered by watering or increased aeration Temps > 160F kill the microbes

Compost-heated water (110F) will be sent to milk house and bumped up another 60F with farm water heater and will serve all the hot water needs in milk house. First facility utilizing this technology saves ≈ $10,000 per year in reduced heating costs Payback for this type of system has to include more than just heat recovery (sale of compost, tipping fees, reduced materials handing, etc.)

Helped design facility over the past year Made sure it is designed for research trials Finishing Corporative Extension report on how to build a heat-recovery composting facility using the isobar heat exchange pipe system (In Review) Developed a standard recipe of farm feedstocks for maximum heat (4 yd 3 bedded pack, 2 yd 3 manure, 2 yd 3 waste feed hay, and 2 yd 3 woodchip) Produces a mix with 30:1 CN ratio, 65% moisture content and a bulk density of 900 lbs/yd 3

Determine optimal aeration intensity (underway) Test to see if intermittent high-nitrogen charges increase heat output to justify time/cost Test various compost covers to see if temperature increases enough to justify time/cost (underway) Compare various feedstock mixing options (bucket method, manure spreader, grain mixer, etc.) on heat recovery Many more to come

The UNH Aerated Static Pile Heat Recovery Compost Facility cost $538,000 (figure also included a remote concrete pad for feedstock mixing) A non-institutional and non-research owner could build a similarly-sized facility for < $300,000 Specific cost structure of UNH cost and that of similarly- sized facility will be in Cooperative Extension Doc coming out this spring Operating Cost - cost $28.28/215 yd 3 (100 ton) batch for electricity (fuel cost is to come)

Charles Simms – Masters student at UNH and summer work study student on the project Zach Charewicz – Undergraduate student at UNH and work study student on the project Tom Oxford – Coordinator of Farm Services Nicole Guindon – ODRF Manager Mark Dill – Assistant Manager at UNH ODRF