Making Waste
Productive
Creating Energy
from Waste
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
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…
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
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
Creating Energy Using the
Anaerobic Process
Conversion of organic material
Raw input material:
Fats, Oils, proteins, starches, carbohydrates, sugars
Methane: 5.6 ft3/ lb COD
Carbon Dioxide
Discharge:
pH
Adjustment
Acetogenic bacteria
break complex food
molecules down to
produce Carbon dioxide
and Acetic Acid
Temperature
Control
Acetic Acid
Methanogenic bacteria
break acetic acid down
to produce Methane
>95% COD Removal
99% BOD Removal
Biomass accumulation:
~1% of Aerobic rate
Digester
• 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
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
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
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
Evaluating Energy Potential
► Demonstration project (pilot) can be an
important step to developing design
► Material handling, gas storage, waste blending
Demonstration Project:
Cheese Plant
► Project timeline: 9-29-05 to 5-25-06
► 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
Demonstration Project:
Cheese Plant
► 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:
Cheese Plant
► Test history
● Permeate (whey filtered to remove protein) fed
to digester (1-18-06―5-25-06)
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)
Demonstration Project:
Cheese Plant
►
Test history: COD
●
Operating at design capacity on permeate
Demonstration Project:
Cheese Plant
►
Test history: methane production
●
Relatively steady
Flow dropped when the gas flow was shut down to clean the gas
discharge line of accumulated moisture
Demonstration Project:
Cheese Plant
►
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:
Cheese Plant
►
Test history: BOD
●
Virtually the entire BOD available has been consumed in the digester
Demonstration Project:
Cheese Plant
►
Test history: alkalinity
●
Stable; most of the alkalinity is retained in the digester, conserving chemical
Demonstration Project:
Cheese Plant
►
Test history: calcium (needed for growth)
●
Sufficient quantities; supplemental calcium is not required
Demonstration Project:
Cheese Plant
►
Test history: hydrogen sulfide
●
A contaminant in the gas could cause operational difficulties in high
concentrations; data inconclusive
Demonstration Project:
Cheese Plant
►
Test history: solids—TS, VS, TSS, VSS
●
TSS-No accumulation of total suspended solids
Demonstration Project:
Cheese Plant
►
Test history: Methane and CO2 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:
Cheese Plant
►
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
Demonstration Project:
Cheese Plant
►
►
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:
Cheese Plant
►
Projected ROI
Demonstration Project:
Cheese Plant
►
Projected ROI
More Information
► Contact NewBio
● www.newbio.com
● mgratz@newbio.com
● 952-476-6194