Design and Modeling of Combined Heat and Power Systems for Sustainable Urban Agriculture and Aquaculture Team Members: Ben Steffes Dan Neumann Brandon Jackson Nate Weber Chris Chapman Faculty Advisor: Dr. Chris Damm Milwaukee School of Engineering

AQUAPONICS OVERVIEW Borrowed from:

CHP OVERVIEW  CHP  Combined Heat and Power  One fuel source for multiple types of output power  Electricity  Thermal Energy  High overall efficiency Fuel Electrical Thermal CHP System

 Develop models to guide in the development of an advanced energy system for aquaponics  System level design of an environmentally responsible and economical system capable of reducing carbon emissions through higher efficiency  Create a simulation tool to aid in the designing and selection of aquaponics energy systems

 Greenhouse Environment between 45-60% relative humidity and 55°F-85°F  Rearing Tank sizes ranging from 1,000-20,000 gallons  Maintain Tank Temperature Between 75°F-85°F  Consider both natural and artificial lighting

DESIGN CONSTRAINTS: POWER PRODUCTION  Provide power to aerate, heat, and pump tank water  Provide power for artificial lighting  Operate on Natural Gas  Continuous Operation With Exception for Maintenance  Less CO 2 emissions than Milwaukee Emission Statistic  Lowest Cost/Least Environmental Impact

INITIAL PLANS  Mechanical  Natural Gas Engine with Heat Exchangers  Supply mechanical demand for:  Pumps  Blowers  Heat exchangers to Provide heat for aquaponics tank(s)  Electrical  Commercial CHP generator set  Supply electricity for:  Pumps  Lighting  Provide heat for aquaponics tank(s)

ELECTRICAL VS. MECHANICAL  Engine Trouble  Introducing lubrication (2-stroke)  Maintenance cycle  Space requirements  Efficiency of Heat Exchangers

MOVING FORWARD WITH ELECTRICAL SYSTEM  Took system level approach to pairing CHP and aquaponics using commercially available CHP generators  Selected Marathon ecopower Borrowed from: mathonengine.com

MARATHON ECOPOWER  Estimated installed system cost approximately $35,000  4000 hour maintenance interval Specifications Electrical Power2.0 – 4.7 kW Thermal Power with max. flow temp. 167 °F [75 ° C] 6.0 – 12.5 kW Overall Efficiency>90% (approx. 25% electrical + approx 65% thermal) EngineSingle-Cylinder, 270 cm 3, 1,700 – 3,600 rpm Exhaust Gas Figures [at 5% O 2 ]NOx < 1.98 mg/ft 3 CO < mg/ft 3 Temp < 194 °F [90 ° C] Grid Feed [Single Phase]250 VAC, 50/60 Hz, Power Factor = 1 Sound Level< 56 dB [A] Dimensions/ Weight54 in. L x 30 in D x 43 H 858 lb ApprovalsCE – Certificate, ETL - Approved

THERMAL MODELING  CHP system sized for thermal load  Point of most efficient operation  Model used to approximate thermal loading  Surface convection and evaporation, wall convection, base conduction, and hydroponic tank losses

 Evaporation (Two Models)  (R.V. Dunkle 1961) Based on model of distillation pond evaporation  (W.S. Carrier 1918) Empirical model based on indoor swimming pools  Surface Convection  Related to surface evaporation (I.S. Bowen 1926)

 Wall Convection  Based on non-dimensionalized analysis of flat plate convection  Hydroponics Tank Losses

PSYCHROMETRIC CHAMBER TESTING Trial 1Trial 2 Tank water temperature (F)~7270 Atmospheric temperature (F)5060 Relative humidity (%)5031 Total run time (min)100210

THERMAL LOAD PROFILE PropertyValueUnits Tank Temperature80F Greenhouse temperature 70F Relative Humidity50F Flow Rate67GPM Return Temperature78F Tank Size 7 width 3.5 height 30 length Ft Number of Tanks2 Rubber Liner0.25Inch Lumber1.5Inch R7 Foam Insulation1.5Inch

AQUAPONIC SYSTEM PROPORTIONING  University of Virgin Islands (UVI)  Raft Style Commercial System  Proportioning Hydroponic Tank to Rearing Tank  Hydraulic Loading Rate  Retention Time  Feed Rate

POWER REQUIREMENTS  Pumping  Centrifugal Pump  45% Efficiency (elec.-water)  Rearing Tank Aeration  Greater Stocking Density  Regenerative Blower  64% Efficiency (elec.-water)  Artificial Lighting  Implemented in few cases  18 Hr daylight grow period  Faster Plant Growth

POWER CALCULATION METHODS

SYSTEM HEAT & POWER REQUIREMENTS SIZED SYSTEM FOR MARATHON ECOPOWER (11000 GALLON) UNIVERSITY OF VIRGIN ISLANDS SYSTEM USING DEVELOPED PROCEDURE (8240 GALLON) System Calculated Power: Pumping: 0.64 Hp (460 W) Aeration: 1.44 Hp (1.06 kW) Lighting: 43.8 Hp (32.7 kW) Thermal: Btu/hr (11.43 kW) Calculated Power: Pumping: 0.50 Hp (370 W) Aeration: 1.1 Hp (800 W) Lighting: None Thermal: None UVI System: Pumping: 0.50 Hp Fish Tank Aeration: 1.5 Hp

RESULTS OF ECONOMIC ANALYSIS Conditions:  $35,000 installed system cost  Analysis uses current utility pricing  CHP system run using thermal load following  Net metering 1:1  Replaces 75% efficient natural gas water heater Results:  31,000 kWh Electricity Generated Annually  83,000 kWh Water Heating  Using 462,000 cu.ft natural gas ($4,300)  $3,000 Annual Benefit  12 year simple payback  10 year payback with 3% inflation  No incentives applied

RESULTS OF ENVIRONMENTAL ANALYSIS Results:  16.4 tCO 2 avoided annually based on Milwaukee emissions profile  14.5 tCO 2 avoided annually based on National emissions profile  Equivalent to approximately 2.8 cars and light trucks not used  20.4 MPG  11,720 Miles

 To provide a selection tool to farmers to assist in incorporating CHP into efficient aquaponics operations

QUESTIONS