Biogas from farm waste, by-products and crops – local solutions for

local issues Stephan Heubeck

Dipl.-Ing. agrar (FH)

M.Eng. Environmental

BANZ conference

Rotorua, New Zealand

16. May 2013

National Institute of Water & Atmospheric Research Ltd.

Dr. Rupert Craggs Group leader

Aquatic Pollution

Dr. Rocky Renquist Crop physiologist &

Director

Bioenergy Cropping Solutions Ltd.

The baseline In NZ we are vey dependent on non-renewable

energy resources

Source: NZMED

Energy Data File

2011

The baseline Agriculture is using a divers mix of energy resources,

but hardly any renewables:

• 2011 net energy use for agriculture, forestry and

fishing sector in PJ/y

• Can the rural sector

expect other sectors

to take up bio-energy

if there is no own use?

Coal Oil N.

Gas Electricity Hydro

Geothermal Solar Wind

Liquid Biofuel Biogas Wood

Ag use

2.60 17.32 1.49 6.97 0 0.68 0 0 0 0 0

Source: NZMED Energy Data File 2012

Biogas

The most versatile renewable energy resource

• From a feed-stock perspective o Manures and Effluents

o Solid waste and processing by-products

o Agricultural residuals and energy crops

• From a digester technology perspective o Thermophilic, mesphilic and cryophillic digestion

o Tank and pond type digesters

o Mixed, static and enhanced surface digesters

• From a scale perspective o From individual farm set-ups to industrial scale

Source: http://www.envitec-biogas.de

Biogas The most versatile renewable energy resource

• Regarding utilisation pathways o Heating

o Electricity generation

o Transport fuel

o Chemical feedstock, synthetic materials

• In addition biogas can be o Stored – short and medium term

o Relatively easy integrated with existing fossil fuel

infrastructure

Biogas could be the corner stone of a

renewable energy future….

However, biogas is a very case specific

technology

Biogas Biogas is a mixture of gases

• Composition may slightly vary: o Feed stock

o Contaminants

o Technology

o Similar to natural

gas

o Corrosive gas

components

o Lighter than air

o Calorific value: ~20MJ/m3

• Properties

Biogas use options Will be determined by goals we want to achieve

o Generally biogas use can be classified for heating, electricity

generation and for transport applications

o Financial attractiveness, GHG reductions, Complexity of the set-up

• 1m3 biogas methane can substitute:

Substitute GHG mitigation Gross value Complexity

~ 1m3 Natural

gas boiler fuel

~ 2 kg kg CO2eq $ 0.20 – 0.50

Scale / location

Simple, cheap and

easy

1.5 – 3 kg

Coal (Lig – SB)

Boiler fuel

3.3 – 3.6 kg CO2eq $ 0.07 – 0.25

Location!

Quite simple and

cheap technology

3 – 3.5 kWh

electricity

NZ: 0.6 – 0.7 kg CO2eq

AU: 2.7 – 3.2 kg CO2eq

$ 0.12 – 0.20 exp +no

REC

$ 0.30 - 0.60 own use

Modestly complex

Modestly expensive

0.9 – 1.05 L

Transport fuel

(Diesel/petrol)

2.4 – 2.7 kg CO2eq

$ 1.00 – 1.20

NZ & AU (no tax)

Complex to organize

Relatively expensive

technology

Biogas use options Biogas heating o Despite its advantages quite uncommon around the globe

other than for domestic applications in developing countries

o Good examples:

o Fonterra Tirau – Natural gas substitution since 1984

o Nelson hospital

o Highly efficient biogas use: 90 – 102% efficiency

o International focus is on biogas generator waste heat utilisation

o Scale: 5kW – 10 MW

Biogas use options

Biogas electricity generation o Base load generation considered to be mastered.

o Reciprocating engines becoming more reliable, performance

of gas-turbines and other heat engines so far disappointing.

o New focus on on-demand and heat governed generation modes.

o Scale: 30 kW – 30 MW

Biogas use options Biogas transport fuel o Purified and compressed biogas (bio-methane) can be

used in any CNG vehicle, however heavy vehicles have

economic and logistic advantages

o Highest financial and ecological value for biogas use

o Chicken and egg problem building up production facility

and user fleet in parallel

o Minimum size: ~500L/day?

Case studies – individual farm

Substrates: Cow shed effluent, feed pad wash,

piggery effluent, other liquid wastes

Drivers: Odour reduction, Solids separation with

effluent storage, On-site energy, GHG

reduction

Technology: Covered Anaerobic Pond

Biogas use: Motor-generator, boiler, flare

Case studies – individual farm

Lepper piggery – Taranaki :

Case studies – individual farm

Benefits: o 40 - 50% instant electricity

savings

o Replacement of heat lamps with reticulated hot water system will see energy self-sufficiency increases to 70 – 85%

o Replacement of heat lamps a long term process

o Gas storage + heat storage = total flexibility

o Ability to keep piggery operational for several days without grid supply

o Payback period < 3 years

Case studies – individual farm Electricity generation record

Case studies – individual farm Dairy farm: Better effluent handling and

energy independence

o Requirement for diary farm effluent storage and / or low rate application technology demands effluent solids reduction

o Covered Anaerobic Pond as an alternative to mechanical solids separators and weeping walls

Case studies – individual farm Dairy farm: Better effluent handling and

energy independence

o Security of supply concerns – Biogas as “regular” back-up

o Options for “the energy independent dairy farm” and biogas as enabler for other renewable generation technologies

o Modelling results positive

Case studies – individual farm Dairy farm: Better effluent handling and

energy independence

o Field scale project under construction in Canterbury at the moment.

Photo taken:

10. May 2013

Case studies – farmer group Example Margarethen am Moos – Austria

o From the farms – for the farms

o 12 Farmer co-operative

o Biogas plant for manure and energy crops from 220 ha

o 625 kW electricity generation – base load

o Waste heat for half the village

o Vehicle fuel station for cars, vans and 2x 200 HP tractor

o Truly on the way to energy independence

Case studies – farmer group Differences to individual farm

set-up:

o Economies of scale to realize high

value uses for biogas, i.e. vehicle

fuel and heat network

o Cooperation to bundle wastes

not enough

o Energy crops to gain scale

Good alternatives for land use

More engineered digester

technology required

o Logistics become the most

important success factor

o Co-operation can solve many

chicken/egg problems

Case studies – farmer group Where is scope for such concepts in NZ:

o As a further alternative in locations where traditional

land use is challenged, i.e. invasive weeds, nutrient

sensitive areas (Taupo), draught areas

o Where complex waste management is part of the mix,

i.e. seasonal fruit and vegetable wastes

o Where energy autonomy based on renewables has additional value, i.e. tourism areas, Maori communities

o In a crisis situation, or wherever the fast start, moderate

scale of the concept provides particular advantages

The New Zealand Institute for Plant & Food Research Limited

Rocky Renquist, Bioenergy Cropping Solutions Ltd

Huub Kerckhoffs, Massey University

Stephan Heubeck, NIWA

Bioenergy Cropping, Nutrient Cycling

The New Zealand Institute for Plant & Food Research Limited

Why biogas transport fuel?

Km travel per hectare – Land efficiency

Source: www.biodieselnow.com/forums/t/19315.aspx

The New Zealand Institute for Plant & Food Research Limited

Biomass Cropping Aims

• Produce biofuels that can be made with local scale

technology and have a high fuel yield per ha: biogas.

• Demonstrate a cropping system in which bioenergy

crops are fertilised with recycled crop nutrients:

the Closed-Loop N system (CLN).

Selected best biomass species

• Identify the best species, those with sustainable high

biomass yield, adapted to sites that are often ‘summer

dry’ and that fit into the resilient CLN cropping system

The New Zealand Institute for Plant & Food Research Limited

Rural benefits

• Substitution of fossil fuels used on the farm

and by rural trucking with local, reliable

biofuels.

• Little need for purchased fertilisers: Use N-

efficient crops plus legumes and recycle

nutrients.

• New land use opportunity: to supply crops to

biofuel producers. Use ‘marginal’ sites where

crops are susceptible to moderate drought stress.

The New Zealand Institute for Plant & Food Research Limited

Forage sorghum (‘Jumbo’)

‘Jumbo’

Sorghum

Kerikeri

2010

2.5m tall

at leaf top

30 tDM/ha

The New Zealand Institute for Plant & Food Research Limited

Forage sorghum (‘Jumbo’)

‘Jumbo’

Sorghum

Hastings

2011

2.5m tall

leaftop

27 tDM/ha

The New Zealand Institute for Plant & Food Research Limited

Jerusalem artichoke, tubers

The New Zealand Institute for Plant & Food Research Limited

Jerusalem artichoke (JA)

JA as an annual crop

(first year plantings) in

Hastings

Shoot biomass

200 days after planting:

2012

31 tDM/ha

2013 (no rain)

16 tDM/ha

The New Zealand Institute for Plant & Food Research Limited

Jerusalem artichoke (JA)

JA as a perennial crop;

(second year)

Shoot biomass

190 days after emergence

in Hastings:

2012

26 tDM/ha

2013 (no rain)

17 tDM/ha

The New Zealand Institute for Plant & Food Research Limited

Giant Miscanthus

Parallel project: other biofuel options

Mxg is a perennial,

highest DM of all

biomass crops

tested in NZ

2013 (dry year!)

Hastings:

36 tDM/ha at late

March peak

(DM% = 47)

The New Zealand Institute for Plant & Food Research Limited

Cropping Conclusions

• The most promising combinations of new biomass species and

legumes to maximise biomass production for biogas on

‘summer-dry’ marginal land:

(1) forage sorghum in combination with

tickbean or crimson clover (H. Bay north)

(2) Jerusalem artichoke and/or lucerne (H. Bay south)

• Our biomass crop yields in good sites:

forage sorghum 20-25tDM/ha + 10tDM/ha for legume

Jerusalem artichoke 16-25tDM/ha

Lucerne 16-22 tDM/ha (3-4 cuttings)

(all are well adapted to the CLN system)

The New Zealand Institute for Plant & Food Research Limited

Rural NZ Biofuel potential

• Biofuel yield from only 5% of ‘summer dry’ land:

3.9 million tDM

900 million m3 methane (630 million m3 net)

(= energy equivalent to 595 million litres of diesel)