Making Waste Productive. Creating Energy from Waste

Transcription

1 Making Waste Productive Creating Energy from Waste 1

2 Creating Energy Inputs from Current Waste Outputs Organic material (waste) can be converted into energy (methane) through a process called anaerobic digestion Applications where waste disposal costs $100,000s/year can be turned into energy worth $100,000s/year Creating Energy Inputs from Current Waste Outputs Two industries suitable to making energy from waste outputs Food industry Cheese/Dairy plants Snack Food plants Prepared Food plants Biofuels industry 2

3 Converting Biomass to Energy The energy value of a waste stream is measured in pounds of chemical oxygen demand (COD) Every pound of COD digested results in 5.6 cubic feet of methane An effective anaerobic digester usually converts 95+% of the available COD into methane Every cubic foot of methane produces around 1,000 BTU s of energy Approximately 5,600 BTUs in a pound of COD A pound of organic solids will contain around a pound of COD A truck load of solids can contain around 50,000 pounds of COD Energy potential to power a 1 MW generator on a continuous basis Segregating Biomass Streams Process and environmental technologies segregate the insoluble fraction of a biomass stream from the soluble Isolate the energy potential material within a facility Clarifiers Screens All types of filtration and dissolved air flotation devices The isolated insoluble high energy potential stream usually ends up on a truck 3

4 Types of Biomass Streams to Consider Hauled material Unsalable product Isolated streams Wastewater In most applications a significant portion of the energy is contained in a small portion of the waste Three Most Common Disposal Methods Land application Landfill Animal feed 4

5 Paying others to haul and dispose of biomass... Is the waste of a valuable asset Stop feeding your cash to cows! How the Anaerobic Process Works to Create Energy 5

6 Creating Energy Using the Anaerobic Process Conversion of organic material Raw input material: Fats, Oils, proteins, starches, carbohydrates, sugars Carbon Dioxide Methane: 5.6 ft3/ lb COD ph Adjustment Acetogenic bacteria break complex food molecules down to produce Carbon dioxide and Acetic Acid Acetic Acid Methanogenic bacteria break acetic acid down to produce Methane Discharge: >95% COD Removal 99% BOD Removal Temperature Control Digester Biomass accumulation: ~1% of Aerobic rate Air is not used so process proceeds at a much lower energy input than Aerobic treatment Factors in Renewable Energy Plant Design Material handling Solids retention Good contact ph control Temperature control Nutrients Gas utilization 6

7 The Economics of Making Waste Productive Factors that Weigh in an Economic Decision Avoided disposal cost Energy value Green value Some options have significant federal/state taxes and other credits Renewable energy credits Emissions trading credits 7

8 Identifying and Evaluating Energy Potential Identifying Energy Potential There is a potential project if Gas costs greater than $7 per MM BTU Electricity costs greater than 7.5 per KWh The plant produces 20,000 lbs. or more COD per day The plant is situated where there is a Renewable Portfolio Standard (RPS) in place Significant avoided cost 8

9 Identifying Energy Potential By geographic area, in cooperation with regional facility (power plant, research facility, cooperative) By individual plant Identifying Energy Potential By individual plant: 3-step process STEP ONE: Data evaluation, using existing plant data Estimate the effectiveness technology to generate energy in the form of methane gas STEP TWO: Lab evaluation, using actual samples of plant residuals and organic waste Determine parameters, limits and potential quantities of methane gas generation STEP THREE: Demonstration project Test the design parameters on waste residuals to finalize the optimum factors for a full-scale plant 9

10 Evaluating Energy Potential Demonstration project (pilot) can be an important step to developing design Material handling, gas storage, waste blending Demonstration Project: Project timeline: to Waste source Permeate stream COD concentration averaged 52,000 mg/l Existing disposal methods Recovery of whey protein concentrate Recovery of lactose Treatment of 350,000 gallons per day of waste in plant-owned treatment plant Trucked 6,000 gallon of waste from WPC and lactose recovery process 10

11 Demonstration Project: Demonstration project goals Replicate a full-scale loading rate 50 lbs of feed COD/1000 gallons of digester liquid volume Determine COD Removal Efficiency Evaluate Gas Quality Evaluate Material handling needs Determine optimum factors for a full-scale plant Demonstration Project: Test history Permeate (whey filtered to remove protein) fed to digester ( ) Average COD strength of 53,000 mg/l Ramped up until the target feed rate of 300 lbs COD/day (50 lbs/1000 gallons of digester volume) 11

12 Demonstration Project: Test history: COD Operating at design capacity on permeate Demonstration Project: Test history: methane production Relatively steady Flow dropped when the gas flow was shut down to clean the gas discharge line of accumulated moisture 12

13 Demonstration Project: Test history: methane flow per unit of COD removed Consistently within the projected flow rate of 5.6 cubic feet of methane/lb of COD Demonstration Project: Test history: BOD Virtually the entire BOD available has been consumed in the digester 13

14 Demonstration Project: Test history: alkalinity Stable; most of the alkalinity is retained in the digester, conserving chemical Demonstration Project: Test history: calcium (needed for growth) Sufficient quantities; supplemental calcium is not required 14

15 Demonstration Project: Test history: hydrogen sulfide A contaminant in the gas could cause operational difficulties in high concentrations; data inconclusive Demonstration Project: Test history: solids TS, VS, TSS, VSS TSS-No accumulation of total suspended solids 15

16 Demonstration Project: Test history: Methane and CO 2 Production Bag samples were collected to verify the accuracy of the on-line instruments that measure COD and methane (two manufacturers = 4 instruments) Demonstration Project: Test history summary Conversion of the dairy permeate to energy is straight forward and achievable Digester operated in a stable fashion No accumulation of COD in the digester Converted 98 percent of the COD (>99% of the BOD) to energy Gas production met the design value of 5.6 cubic feet of methane/lb of COD removed Energy breakdown 80% to 100% of gas demand 1 MW power output plus heat recovery Status Demonstration project completed Final plant design 16

17 Demonstration Project: Projected ROI Assumes output of gas to be burned in boilers or fed into a co-generation facility to generate electricity and waste heat Option A assumes the addition of a co-generation unit and the recovery of heat from that unit Option B assumes that the biogas is only burned in existing boilers Both options assume the biogas plant is NewBio s property and the biogas utilization equipment is the client s property Calculations based on 120 months contract term No Green Credits included Demonstration Project: Projected ROI 17

18 Demonstration Project: Projected ROI Contact NewBio More Information