Links of the Biodigester sector with the

Dairy sector and Environment

Peter Bos

CLEANED Project East Africa Stakeholder Consultation on Dairy and Environment Nairobi, Kenya, 18 September 2013

SNV- TA

1 Outline

Intro on Biodigester

Dairy – Biogas sector

Bio-slurry as fertilizer

Energy use for dairy

farmers

Improved Environment

2. Biodigester unit

3

Fig 1:

Fixed dome domestic biogas installation

Fig 1:

Fixed dome domestic biogas installation

4Title

5Title

The feasibility nexus

Technically possible

Economically attractive Environmentally sustainable

Socially acceptable

Programme environment

Political context

Feasibilitynexus

6Title

Financial and economic performance of domestic biogas installations

SNV Dom. Biogas Programs

AsiaNepalVietnamCambodiaBangladeshLaosPakistan Indonesia

AfricaRwandaEthiopiaTanzania Kenya UgandaBurkina Faso

3. Dairy and biogas

• Traditionally, small scale biogas and small scale dairy have always

been having tight links.

• => From a biogas point of view: zero stabled- dairy cows / overnight

stabling, are the producer of the substrate for the biogas installation.

• => From a dairy perspective: a biogas installation contribute to a

proper and hygienic management of cow dung, the production of

energy for hot/warm water to clean milking equipment and cattle

before and after milking, nutrients cycling….

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Biochemical processes and biogas

The dairy cow

Mature “developed (!)” dairy cow Live weight 635 kg

Milk production 20 – 35 kg / day

Main dung characteristics:

Daily fresh manure production: 51 kg per day (61 litres / day)

Total solids: 6.4 kg (TS (= DM) ~ 13% of fresh wght)

Macro nutrients: Micro nutrients / trace elements

Nitrogen Nk:

Phosphorus P: 0.04 kg

Potassium K: 0.16 kgTypical substrates

Cow dung 0.025 0.050Pig dung 0.040 0.070Poultry litter 0.065 0.120Nigh soil 0.030 0.070

specific biogas production

[m3/kg]

“Developing” cattle:

• Weight <250 kg

• Milk production 1-5 kg/day

• TS >20% of fresh wght

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Farm system

Crop production system

Householdsystem

Animal production system

Biogas plant

Bio slurry

4. Bio-slurry as fertilizer

Improved soil fertility:

• Higher yield kg/ha

• Better quality, higher price/kg

• Savings on chemical fertilizer

• Savings on pesticides

Bio-slurry can be used fresh

or mixed with agricultural

residues to make compost!

Often the financial benefits of

bio-slurry is greater than that

of biogas!

11Title

Slurry use for aqua culture

• Food for fish

• Fast uptake of inorganic

materials by plankton

• Plankton food for fish

• Little use of O2, better water

quality

• Less risks for fish diseases

• Increase in fish growth of 15-

30% compared to fresh dung

12Title

Bio-slurry

• Dehydrated digested sludge can be used as feed supplement

for pig and poultry.

• Mushroom farming: increase in yields of 15% more compared to

that of usual medium using bio-slurry and reducing pick time by

7 days.

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Wet Application

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Dry Application

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Bio-slurry use matters!

Small fraction of soils: < 2 % (in tropics)

OM:

• Living organisms: roots, fungi, earthworms, etc.

• Dead material: plant residues, fym, compost, humus, etc

Positive effects:

• Soil structure (roots, air)

• Water retention capacity

• Soil fertility (CEC = cation exchange capacity)

• Buffers soil pH

• Resistance to erosion

5. Energy use for dairy farmers

• Use of biogas for heating of water to clean milking equipment

and cattle before and after milking.

• To a lesser extent, biogas-energy has been applied for on-farm

milk processing, mainly pasteurizing raw milk

• Innovative idea; use of biogas for milk chilling at HH level

both micro-scale (6-16 M3) and medium sized digesters (24-60

M3).

- special designed milk coolers operating on biogas

- use of generators operating on biogas

Preliminary calculations indicate that the per-head production of

cattle dung produces sufficient energy to cool down the per head

milk production.

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Domestic biogas & carbon revenue

6. Improved EnvironmentBiogas & GHG reduction

Manure handling modality

Fossil- and NRB fuel

substitution

Chemical fertilizer

substitution

Project boundary

Animal manure storage

Biogas stove(thermal energy to the user)

Fertilizer for fields

manurebiogas

Bio

-slu

rry

Concluding

• The impact of a biogas installation on the dairy quality is high; -

improved hygienic conditions and cleanness

• - energy for heating, pasteurisation and possible chilling

• - organic potential fertilizer for crops / fodder grasses /

fishponds.

• - reduced GHG emissions by saving NRM fuels.

• => resulting that Nestle supported the construction of bio-

digesters for all its farmer-producers in Indonesia.

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Asante sana!

SNV - KenyaPeter Bos, Senior Advisor Renewable Energypbos@snvworld.orgwww.snvworld.org, http://africabiogas.org/

For more information, please contact:

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Plant nutrients

Macronutrients   • Primary: nitrogen (N), phosphorus (P), potassium (K)• Secondary: calcium (Ca), magnesium (Mg), sulphur (S)

Micronutrients (trace elements)• boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn),

molybdenum (Mo), zinc (Zn)

Non-Mineral Nutrients• hydrogen (H), oxygen (O), carbon (C)

Measured: dry weight in % or g/kg or ppm (= parts per million)

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Macro nutrients

Nitrogen (N)

• proteins, enzymes and metabolic processes.

• chlorophyll ⇨ photosynthesis. 

• rapid growth, seed and fruit production, quality.

Phosphorus (P)

• photosynthesis rapid growth. 

• formation of all oils, sugars, starches, etc.

• encourages blooming and root growth.

Potassium (K)

• building of protein, photosynthesis, fruit quality.

• reduction of diseases.

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Fertilizers

Organic fertilizer:

Broad range of nutrients

Low in N-P-K

Long term effect (indirect)

Soil organic matter content

Chemical fertilizers:

Short term effect (direct)

High in N, P or K

Integrated Soil Fertility Management:

Optimal combination of organic and chemical fertilizers

Domestic biogas & carbon revenue

Manure handling modality

Methane emissions per animal type “i” in “j” systems:

CH4i = ∑j Bo

i x VSi x MS%ij x MCFj

CH4= Methane emissions [kgm-3]

Bo= Biodegradability [m3 CH4 (kgVS)-1]

MS%= Manure management system usage [%]MCF= Methane conversion factor [%]VS= Volatile solids [kgyr-1]

Domestic biogas & carbon revenue

Biomass and fossil fuel substitution

Baseline emissions for thermal energy for one household:

BEth, h = ∑j (( F i,bl,h) x NCVi x EFco2i)

Beth,h = Baseline hh emissions from thermal energy [t CO2eq]

Fi, bl, h= Amount of fuel i in baseline situation per hh [kg, m3 or ltr]

NCVi = Net calorific value fuel i [GJkg-

1etc]EFco2

i= CO2 emission factor for fuel i [tCO2kg-1]