1. Department of Environmental Organic Chemistry and Technology (EnVOC)
Co-digestion of agricultural waste and cow manure to supply cooking fuel and fertilizers in rural India: life cycle assessment and substance flow analysis
Sophie Sfez, Steven De Meester, Jo Dewulf
16th International Waste Management and Landfill, S. Margherita di Pula, Italy – 2-6 October 2017

2. Introduction

3. Percentage share of households by type of cooking fuels
Introduction
In India, 86% of households use biomass as cooking fuel
Source: Reuters
Percentage share of households by type of cooking fuels
(Census of India 2011)

4. Introduction
20% of rice straw is either burnt (62%) or left of the field
PM2,5
PM10
SO2
CO2 CO
NOx
NH3
CH4
NMVOC
N2O
Emission factors a
(g kg DM-1)
5.8
6.4
0.4
1204.0
87.3
2.3
2.6b
9.6
7.6c
0.07d
a Average values from Kanabkaew and Kim Oanh (2010); b average values from Kanabkaew and Kim Oanh (2010) and McMeeking et al. (2009); c EEA (2013);
d Chang et al. (2013)
 Available for further use
Photo by Jeff Schmaltz / NASA

5. Introduction
New systems are being introduced to tackle these challenges  anaerobic digestion is a promising option
The new systems need to be assessed to see how they can or cannot contribute to reach sustainability targets set by India:
20 to 25% of GHG reduction from 2005 to 2020
Energetic self-sufficiency objectives set by the Indian energy policy

6. Materials and Methods

7. Materials and methods Analysis for the state of Chhattisgarh (rural)
1.4x1010 MJ energy for cooking per year; 92% of households use firewood
8.5x106 tons year-1 of rice straw  10% available for other uses
5270 kt per year of cow dung from household cattle
Google maps
Amount of household cow dung per usage in Chhattisgarh (kt year-1)

8. Materials and methods
Nasery 2011
Sfez et al., 2017

9. Materials and methods Functional unit:
Cooking energy: 1.4x1010 MJ year-1
Nutrients made available for crops:
236 kt of N
157 kt of P
69 kt of K
Nasery 2011
Sfez et al., 2017

10. Materials and methods Data inventory
Foreground system: based on literature data
transfer coefficients of N, P and K and form under which emitted for the two scenarios
theoretical biogas potential of the mix of cow dung and rice straw and its CO2 and CH4 composition based on their macro-nutrient composition
Background system: ecoinvent 3.1

11. Materials and methods Substance flow analysis
A substance flow analysis is conducted for N, P and K (foreground system)
“Nutrients dependency factors” are calculated for each nutrient
quantity of nutrient n imported from external sources into the rural community
𝐷𝐹n = 𝑄n imported 𝑄n soil
quantity of nutrient n made available for plants

12. Materials and methods Assessment of the impact on human health
A life cycle assessment is conducted to assess the impact on human health…
HHI = FFi × EFi × DF
Fate factor
Effect and Damage factors (from ReCiPe endpoint method)
Human Health Impact (DALYs)

13. Materials and methods Assessment of the impact on human health
A life cycle assessment is conducted to assess the impact on human health…
HHI = FFi × EFi × DF
Fate factor
Effect and Damage factors (from ReCiPe endpoint method)
Human Health Impact (DALYs)
Emissions inhaled by the global population:
FF from ReCiPe endpoint method
Specific FF for emissions inhaled by the local population:
from indoor fuel combustion: 0.034% of emitted PM
from outdoor burning of rice straw: 0.01% of emitted PM

14. Materials and methods Assessment of the impact on climate change
The ReCiPe midpoint method is used
Emissions from the foreground system
Emissions from the background system

15. Results

16. Nutrients dependency factors (%)
Results
Nutrients dependency factors
Current scenario
Prospective scenario
Nutrients dependency factors (%)
DFN
98.5
98.4
DFP
98.0
96.4
DFK
78.8
54.6
-0,1%
-1,6%
-31%

17. Results Nutrients dependency factors Current scenario
Prospective scenario
Sfez et al. 2017
Large content of K in manure (2.9%)
11% of K applied via manure
Large impact on K flows

18. Results Impact on human health
In the prospective scenario, the HHI drops by 48%
Biogas production avoids the combustion of kt of firewood
Global impact represent less than 0.7% of the HHI
-48%
Sfez et al. 2017

19. Results Impact on climate change
Large contribution of avoided firewood combustion and rice straw burning to decrease the carbon footprint of the prospective scenario
BUT part is replaced by new emissions from composting and fugitive emissions
A large share of the footprint occurs outside of the state  the leeway to reduce it by implementing the prospective scenario is limited
-13%
50%
57%

20. Conclusions

21. Conclusions
Anaerobic digestion of cow dung and rice straw has a large potential to help Chhattisgarh tackling several challenges
It can contribute to reduce by
more than 30% the dependency of farmers on synthetic potassium
48% the impact on human health
13% the impact on climate change
The barriers to the pratical implementation of anaerobic digestion should be analyzed to evaluate its full potential

22. Conclusions
SFA and LCA were combined to provide a complete overview of the impact of the prospective scenario on nutrients flows, human health and climate change
A thorough literature review on emissions had to be done
There is a need for the scientific community to share data on the emissions from organic waste management, especially under tropical conditions
In the context of circular economy, gate-to-gate indicators should be used to complement results from LCA studies

23. Thank you! ir. Sophie Sfez Department of Environmental organic chemistry and technology E T
Ghent Ghent University