Heat from CompostHeat from Compost

A Compost Story by Sam RogersA Compost Story by Sam RogersRMC Green TeamRMC Green Team

OutlineOutline

BackgroundBackground Project – extracting heat from compostProject – extracting heat from compost

HistoryHistory Two prototypesTwo prototypes

ResultsResults Future workFuture work

Questions and commentsQuestions and comments

Who We AreWho We Are

The Royal Military College (RMC) Green The Royal Military College (RMC) Green TeamTeam Program supervisor – Major Nicholas Program supervisor – Major Nicholas

VlachopoulosVlachopoulos Project managers / engineers – Sam Rogers Project managers / engineers – Sam Rogers

and Ted Baileyand Ted Bailey Summer student Mark DavisSummer student Mark Davis

The Green TeamThe Green Team

Department of National DefenceDepartment of National Defence Environmental stewardshipEnvironmental stewardship

Mission – promote DND as environmental Mission – promote DND as environmental leaderleader

Projects / capabilitiesProjects / capabilities Resource managementResource management

Water, wastewater, stormwater, solid wasteWater, wastewater, stormwater, solid waste Energy managementEnergy management

Savings, management, planning, sustainabilitySavings, management, planning, sustainability

The Project BeginsThe Project Begins

Two aerobic, in-vessel composters at Two aerobic, in-vessel composters at CFB TrentonCFB Trenton Compost the Base’s food wasteCompost the Base’s food waste Roads and Grounds managerRoads and Grounds manager

Noticed the large amounts of heat generatedNoticed the large amounts of heat generated Can we save energy and $$$?Can we save energy and $$$?

Called in the Green Team!Called in the Green Team! Here’s what we foundHere’s what we found

The CompostersThe Composters

Two composters (one currently not used)Two composters (one currently not used) 1500 and 2000 lbs/day capacity 1500 and 2000 lbs/day capacity

Manufactured by Wright EnvironmentalManufactured by Wright Environmental In-vesselIn-vessel Step feed, conveyer systemStep feed, conveyer system One tonne 3 times/weekOne tonne 3 times/week 28 day retention cycle28 day retention cycle

Compost is cured in pilesCompost is cured in piles

Composter SchematicComposter Schematic

Three separate zonesThree separate zones Compost moves on palatesCompost moves on palates

Pushed through with a hydraulic ramPushed through with a hydraulic ram Fans control air circulationFans control air circulation Biofilter removes odorsBiofilter removes odors

Where is the Heat?Where is the Heat?

First chamberFirst chamber Hot compostingHot composting

Compost 55-70 Compost 55-70 ºCºC Compost cooler in other chambersCompost cooler in other chambers

Freezes at the outlet in the winter!Freezes at the outlet in the winter!

Historical dataHistorical data

Where Will the Heat Go?Where Will the Heat Go?

Possible sourcesPossible sources Heating the compost buildingHeating the compost building

Building has inefficient electric space heatersBuilding has inefficient electric space heaters Often left openOften left open

Heating nearby hot water tanksHeating nearby hot water tanks Use 1-2 tanks/ day on-siteUse 1-2 tanks/ day on-site

Greenhouse boilerGreenhouse boiler Greenhouse near compostersGreenhouse near composters Shut down in winter to save energyShut down in winter to save energy

How Will We Get Heat?How Will We Get Heat?

Design considerationsDesign considerations Easy to operateEasy to operate Large forces in the compostLarge forces in the compost

Idea #1 – “Heat Spike Method”Idea #1 – “Heat Spike Method” Direct heat transferDirect heat transfer Run water through pipes embedded in Run water through pipes embedded in

compostcompost

Heat Spike MethodHeat Spike Method

Direct heat transfer Direct heat transfer From the compost to water inside the pipesFrom the compost to water inside the pipes

RemovableRemovable As compost palates are moved through, As compost palates are moved through,

pipes are retractedpipes are retracted Relatively inexpensiveRelatively inexpensive

Pipes, a pump, a ram systemPipes, a pump, a ram system

ComposterComposter

Side ViewSide View

““Spikes”Spikes”

Set of SpikesSet of Spikes

Pipe detailPipe detail

Spikes withdrawnSpikes withdrawn

Spikes insertedSpikes inserted

Isometric ViewIsometric View

Prototype – Heat SpikePrototype – Heat Spike

Let’s test it!Let’s test it! Prototype built with materials from RMCPrototype built with materials from RMC One spike, ½ inch copper pipeOne spike, ½ inch copper pipe Run water through and note temperature Run water through and note temperature

changechange Change flow rateChange flow rate Timed testsTimed tests

Heat Spike Heat Spike PrototypePrototype

Temperature Temperature MeasurementMeasurement

The “C” TeamThe “C” Team

TestingTesting

So who’s going in?

The summer The summer student!student!

Spike insertedSpike inserted

SpikeSpike

ThermometerThermometer

Phew!Phew!

Results – Heat Spikes Results – Heat Spikes

Very encouraging!Very encouraging! Large temperature changes at low flow ratesLarge temperature changes at low flow rates 55°C / meter of pipe at 0.42 L/min°C / meter of pipe at 0.42 L/min Napkin calculationNapkin calculation

10m of pipe can heat 600L of 4°C water to 50°C 10m of pipe can heat 600L of 4°C water to 50°C per day!per day!

Significant heat!Significant heat!

Is this energy transfer sustainable?Is this energy transfer sustainable?

45 Minutes

ResultsResults

Heat transfer rate rapidly decreasesHeat transfer rate rapidly decreases ~0.5~0.5°C after 1 hr°C after 1 hr

Why?Why? Compost an insulatorCompost an insulator Condensation on pipesCondensation on pipes

Killing the processKilling the process Investigating other reason as wellInvestigating other reason as well

Conclusions?Conclusions?

Back to the drawing boardBack to the drawing board Other ways of getting heat?Other ways of getting heat?

Air above compost was warmAir above compost was warm 35-5035-50°C in 1°C in 1stst chamber chamber

How Will We Get Heat ReduxHow Will We Get Heat Redux

ThermosyphonsThermosyphons Heat pipesHeat pipes

Isobars by Acrolab!Isobars by Acrolab!

Isobar maintains a constant temperature Isobar maintains a constant temperature over its surfaceover its surface Heat transferHeat transfer

Isobar MethodIsobar Method

Mount water tank on composter exteriorMount water tank on composter exterior Mount isobars on composter interiorMount isobars on composter interior

Drill holes and “plug” isobars into water tankDrill holes and “plug” isobars into water tank

Isobars heat Isobars heat water in tankwater in tankWater Water pumped to hot pumped to hot water tank or water tank or boilerboiler

Isobar PrototypeIsobar Prototype

PurchasedPurchased Water coolerWater cooler IsobarIsobar

PrototypePrototype Drilled a holeDrilled a hole Inserted isobarInserted isobar Attached thermometersAttached thermometers

Ready to go!Ready to go!

IsobarIsobar

CoolerCooler

IsobarIsobar

ThermometersThermometers

Ambient Temperature 46.5 °C

ResultsResults

9L of water heated 18.5 9L of water heated 18.5 °C in 2 ½ hrs by °C in 2 ½ hrs by one isobarone isobar

Another napkin calculationAnother napkin calculation 5 isobars, 200L tank5 isobars, 200L tank Tank would increase ~40 °C per dayTank would increase ~40 °C per day Lots of assumptions made!Lots of assumptions made!

Project futureProject future

TestingTesting Zone 1 air temperature (especially in the winter)Zone 1 air temperature (especially in the winter)

More isobar testingMore isobar testing Flowing waterFlowing water Colder waterColder water Effects on chamber temperature, fan useEffects on chamber temperature, fan use Working conditionsWorking conditions

Moisture, blades, etc.Moisture, blades, etc.

Getting the water to its destinationGetting the water to its destination

Future Part 2Future Part 2

If testing results are positiveIf testing results are positive Build a working prototypeBuild a working prototype

TestTest

If final prototype works, construct a fully If final prototype works, construct a fully functional devicefunctional device

Save some energy!Save some energy!

Questions and CommentsQuestions and Comments

Thank you!Thank you!

ContactContact srogers@rmc.casrogers@rmc.ca