WASTE NOT WANT NOT:

Waste to Energy a Sustainable

Technology for All

Prof Diane Hildebrandt

Director of IDEAS (Institute for the Development Of Energy for African Sustainability)

University of South Africa

Introduction to UNISA• UNISA is a mega University with about

400 000 students

• UNISA has set up the Science campus in

Florida

• Has state of the art facilities

• Has full time postgraduate students in

Science and Engineering

Introduction to IDEAS

IDEAS stands for Institute for the Development of

Energy for African Sustainability

We research in a number of areas:

Reactor design (Attainable Regions)

Separation design (Column Profile Maps)

Process Design for improved process

efficiency

Fischer Tropsch

THE VISION

Our vision is to change the landscape by turning waste and other under-utilisedresources into fuel, electricity and jobs

through strategic partnerships.

Our work is particularly aimed at Africa and the Developing World

Acknowledgements

This talk is based on years of research

in this area by myself, my colleagues

and post graduate students

Thanks to all who contributed

IDEAS:

Research focuses on environmentally responsible chemical conversion technologies, with particular emphasis on:

• Utilizing surplus and underutilised resources, such as municipal waste and sewerage

• Sustainable small scale solutions which are modular and flexible in their applications

Waste in Informal Settlements

Informal settlements may occupy land

illegally

In many cases government unable to

provide services

No adequate waste management

system

Serious health and safety risk

especially in children

Social Challenges

• In some cases no adequate sanitation

systems this causes health problems

• Economic and social marginalization

• 26% unemployment rate (>53% youth)

Access To Energy in Informal

Settlements• Energy Poverty

• Illegal and unsafe electrical

connections

• Cause most incidence of fire and

accidental electrocution

Waste: A Problem or an

Opportunity?WASTE

Clean and

Improved

Energy

Gasifier Bio-digester

Dry Carbonaceouswaste

Wet Waste

How much energy is there in

human waste?In 2012 world consumed around 5 x 1020 J of energy

Humans produce around 866 billion kilograms per year of faeces

This could produce around 6 x 1018 J/year of energy

Thus 1/100 of the world’s energy needs could be produced from human waste

http://large.stanford.edu/courses/2010/ph240/cash2/

What about other waste?

A cow produces up to 30-50 kg / day of wet

manure

This could be converted to around 300-1000

l/day of biogas

A gas burner of a stove uses around 50

l/hour of gas when simmering

could cook for 2-4 hours a day using the

manure from 1 cow

Powered by waste

Consider a rural family who

Cooks on a 2 plate stove for 2 hours a day at

simmer

Heats up 40 l/day water to 50 OC

1 cow together with the families human waste could

supply this energy.

Thus we could power households on animal and human

waste

Which wastes could we use?

All organic wastes can be used:

Organic municipal waste

Manure (pig, cow, chicken, …)

Grass, straw, hay etc

Industrial waste such as bagasse, sawdust

Why do we not utilise waste?

Questions

Is anaerobic biodigestion not widely used because:

It is technically difficult?

Economically not feasible?

It is not robust?

Social issues?

Others?

Have a team at UNISA looking at these issues

Social Scientists

Business

Psychologists

Engineering

Biotech

Microbiology

Large Scale Applications of Anaerobic

Digesters

Livestock waste

Municipal organic waste

Farming

Electricity

Generator

Heat

Transport

Large scale uses of biogas

Anaerobic

digester

Biogas

Slurry/bio-fertilizer

Commercial use of biogas

• BMW SA – Plans on running Rosslynproduction facility on biogas (25-30%of power using renewable).

• Biogas will be supplied from the 4.4

MW capacity Biogas plant inBronkhorstspruit.

• Novo Energy, has plans of building adispensing station for demonstration

purposes on a landfill site near ORTambo International airport.

• They plan on offering motorists freeconversion so that their cars can run

on biogas.

• They estimate a fuel savings ofbetween 15% and 25%.

Rosslyn production facility

Gas powered vehicle

COJ waste water treatment plant

• City of Johannesburg water utility –In 2013 launched a pilot BiogasProject at the Northern Works WasteWater Treatment Plant.

• In 2012 the cost of treating wastewater had escalated R300 millionper annum from R93 million perannum in 2010. This was excludingEskom’s annual increases.

• The city’s 6 treatment plantscurrently treat 1 billion litres ofsewage per day.

• This has the potential of producing8.5 MW of electricity (Peter Louw).

• Johannesburg Metro Buses to runon biogas?

Difficulties with large scale

digesters

Transportation of waste is not economical

There is no supportive legal framework

There is no policy support leading to no standards for

biogas

Lack of financial mechanisms

Complex administrative processes, especially at

municipal level

Have to register for NERSA

Small Scale Biodigesters?

Farming

Electricity

Generator

Geyser

Bio-digester

Anaerobic

digester

Slurry/bio-fertilizer

(With potentially

less Pathogens)

Cooking

Lighting

Biogas

Wet Waste

Economic Benefits

• Saving on fuel sources.

• Free energy from own waste (kitchen,

sewage).

• Reduce the need to buy chemical

fertilizers.

• Easy disposal of livestock waste.

Health Benefits

• Removes pathogens from waste.

• Reduced health risks.

Advantages of Biogas

Implementation by UNISA

Engineers Without Borders UNISA

• Set up digesters at Muldersdrift

• Is working well• Uses ½ a bucket of manure every

second day

• Cook for 4 hours a day on this

• No longer uses LPG or paraffin for cooking

• Also used for Lighting

Further Implementations

13 digesters put in Eastern Cape

Joint project with SANEDI, University of Fort Hare and

UNISA (Prof Godwell Nhamo Institute for Corporate

Citizenship and IDEAS)

Now installing 20 small digesters in Gauteng

Funded SANEDI and Exxaro

Business Case study for suppling

biogas to informal settlement

Working with overseas company

Looking at using sewerage as feed to biogas system

Energy to feed either:

Households

Public facility such as clinic or school

Proposed Site

Proposed System

Proposed Pilot

Proposed to use 20 households in pilot

Collect sewerage from household

Supplement with Manure from neighboring farms

Supply 2 – 3 hours of gas per day to each household

The business case?

Basis

municipality pays what it currently costs to empty

existing pit latrines

Sell fertilizer and gas

Can create 6 jobs for the 20 households

Payback period of about 5 years

Processing Dry Waste

WASTE

Clean and

Improved

Energy

Gasifier Bio-digester

Dry Carbonaceouswaste

Wet Waste

Converting dry waste to

energy

Typically use high temperature route called gasification

Convert waste to a gas mixture of CO and H2

This gas can be converted to

Electricity: (1ton of waste per hour produces

approx. 2 MW electricity)

Fuel via XTL: (1 ton of waste produces approx. 1

bbl synthetic crude)

Heat

The Gasification Unit

Hot Water tank

Solid Waste

Steam Engine

Syngas

Gasifier

Ash

Compressed Air

Boiler

Exhaust Gas

HP-Steam

Cold Water Supply

Hot water

Condensate

Power to Air compressor

Air Compressor

Feed Air

Elect-power to pump

Elect-Pow

er to

Hou

se

He

at Energy

Ho

t water to

show

er

LP-Ste

amBo

iler Feed w

ater

Hot Water Heat Exchanger

Cooking or heating

Boiler Feed Water Pump Condenser

PR-Valve

PR-Valve

PR-Valve

Gasification system line

Steam System line

Hot Water Line

Electrical power line

Heating Energy

Mechanical Power

• Small scale gasification system : approx. 10kg/hr of waste

Biomass

CGasification

process

Low temperature (Co based catalysts) Medium to Heavy

products

High temperature (Fe based catalysts) Lighter products

Coal

Natural gas

B

G

XTL (synthetic fuels technology) = GTL, CTL or BTL

Syngas Products

Fischer- Tropsch Synthesis

What is ‘XTL’?

o Waste Residue oil

o Waste Plastics

o Biomass

o Wood chips

o Stranded Gas

Can be used as feeds in XTL plants = WtL (Waste to Liquid)

All Contain (-CHxOy-)

Waste to Liquid plant:-

(-CH-)nFeedstock

Waste to liquid conversion(-CHxOy-)

✓ CxHy gases

✓ Naphtha

✓ Diesel

✓ Waxes

✓ Base oilsproducts

Other sources of Carbon!

Energy Integration System (Steam, Cooling Water, Heat Exchangers)

Feed

Steam

Steam Reforming

Gas cleanup

FT Separation

Heat Energy

Raw

Syngas

Syncrud

e

▪ Gasoline▪ Diesel ▪ Wax

Clean

Syngas

FT H2O

(-CH-)n

WtL Process - uses Fischer Tropsch (FT) reaction to produce syncrude

Full demonstration of biomass to syncrude process

Air blow down draft biomass gasification

Syngas conditioning

Fischer Tropsch Synthesis

0.5 L a day production capacity

Successfully commissioned in 2012

Previous experience: BtL Pilot Plant

Small Scale GasificationHave two gasifiers that we are testing, both handling

300 kg/day

Fixed bed down draft gasifier

Plasma gasifier for larger systems or for treating with

dangerous waste (e.g. hospital waste)

Plasma GasifierUNISA designed Fixed Bed gasifier

UNISA Laboratory facilities at NECSA

A Paradigm Shift?

How can we make small processes that convert waste and biomass

to fuel, electricity, heat and which are:

• Socially acceptable• Environmentally friendly

• Efficient

• Cheap

• Simple

• Robust

Thank YouDiane.hildebrandt@outlook.com