11.1 Bijlage van inspreker: WLR Rapport 2022 - VTTI

Emission calculations for a central codigestion plant

Model study for VTTI Bio-energy Tilburg (VBT)

Flavia Casu, Ilse Groeneveld, Nico Verdoes

Wageningen Livestock Research

Wageningen Livestock Research Wageningen, May 2022

Confidential report

Casu F.A.M., I. Groeneveld, N. Verdoes, 2022. Emission calculations for a central co-digestion plant. Model study for VBT. Wageningen Livestock Research, Confidential report. Deze studie onderzoekt het effect op de stikstof- en broeikasgasemissies wanneer vleesvarkensdrijfmest en -vaste mest wordt verwerkt door VTTI Bio-Energy Tilburg (VBT); een covergistingsinstallatie welke in Tilburg zal worden gebouwd. Middels een emissie- en massabalansmodelstudie zijn verschillende scenario’s doorgerekend, waarbij verschillende varianten van het VBT scenario worden vergeleken met een referentiescenario waarin mest niet verder wordt verwerkt. Hierbij is ook het transport van de mest(producten) toegevoegd, waarbij de producten binnen Nederland, naar Frankrijk of Vietnam worden getransporteerd. The goal of this study is to gain insight in the effects of processing pig manure through the new VTTI Bio-Energy Tilburg (VBT) processing facility that will be built in Tilburg (The Netherlands) with regards to nitrogen and greenhouse gas emissions. Through a model, different variants of the VBT scenario are compared with a reference scenario where manure is not further processed.

Calculation on these emissions based on mass balances and emissions factors were done along the entire manure processing chain: from excretion of manure in the housing system to application of the manure products on the field. Furthermore, emissions during transport of the manure (products) to the Netherlands, France and Vietnam are included as well.

Dit werk valt onder een Creative Commons Naamsvermelding-Niet Commercieel 4.0 Internationaallicentie. © Wageningen Livestock Research, onderdeel van Stichting Wageningen Research, 2021 De gebruiker mag het werk kopiëren, verspreiden en doorgeven en afgeleide werken maken. Materiaal van derden waarvan in het werk gebruik is gemaakt en waarop intellectuele eigendomsrechten berusten, mogen niet zonder voorafgaande toestemming van derden gebruikt worden. De gebruiker dient bij het werk de door de maker of de licentiegever aangegeven naam te vermelden, maar niet zodanig dat de indruk gewekt wordt dat zij daarmee instemmen met het werk van de gebruiker of het gebruik van het werk. De gebruiker mag het werk niet voor commerciële doeleinden gebruiken. Wageningen Livestock Research aanvaardt geen aansprakelijkheid voor eventuele schade voortvloeiend uit het gebruik van de resultaten van dit onderzoek of de toepassing van de adviezen. Wageningen Livestock Research is NEN-EN-ISO 9001:2015 gecertificeerd. Op al onze onderzoeksopdrachten zijn de Algemene Voorwaarden van de Animal Sciences Group van toepassing. Deze zijn gedeponeerd bij de Arrondissementsrechtbank Zwolle.

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Table of contents

Preface

5

Summary

6

1

2

Introduction

8

1.1

8

Goal of the study

Method

9

2.1

Emission calculations

9

2.2

Scenarios

11

3

Results

13

4

Discussion

16

5

Conclusion

18

Literature

19

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Preface

A more general study into the valorisation of pig manure in 2021, raised the question at VBT to calculate the emissions for their planned installation. In this way, scientific substantiation can be provided for the possible emission reduction in the entire production process: from the animal (manure production) to the application as a manure product on the ground. We thank the client for setting up this study and hope that it will be helpful to make the right choices in realizing their manure valorisation plant.

On behalf of the research team, Nico Verdoes, project leader

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Summary

The goal of this study is to gain insight in the effects of processing pig manure through the new VTTI Bio-Energy Tilburg (VBT) processing facility that will be built in Tilburg (The Netherlands) with regards to nitrogen and greenhouse gas emissions. By use of an emissions model, calculation on these emissions based on manure content, mass balances and emissions factors were done along the entire manure processing chain: from excretion of manure in the housing system to application of the manure products on the field. The emission model was extended with a transport section, to include ammonia and greenhouse gas emissions linked to transportation of the manure products. Transport emissions were calculated with emission factors taken from the life cycle inventory database Ecoinvent. In order to gain insight in the nitrogen and greenhouse gas emissions along the entire manure processing chain, different scenarios were evaluated: ▪

Reference scenario: Slurry and solid manure from fattening pigs are collected. Part of the solid manure is composted. The slurry, solid manure and composted solid manure are applied as such on the field.

▪

VBT standard scenario: Slurry and solid manure from fattening pigs are collected every two weeks and transported to the VBT processing facility. Through co-digestion and further processing, these fractions are converted into fertilizer pellets and applied as such on the field.

▪

VBT variations o

1 week: Same as standard scenario but with a manure collection frequency of 1 week;

o

3 week: Same as standard scenario but with a manure collection frequency of 3 weeks;

▪

Reference scenario ‘new norm’: Same as the reference scenario, but all housing systems are equipped with an air scrubber in order to reduce ammonia emissions from the stable.

Table S.1 gives an overview of the total ammonia and methane emissions for both the reference scenario and the standard VBT scenario. Table S.1

Total emissions of the reference and VBT scenarios.

Scenario

Ammonia emission

Methane emission

Greenhouse gas emission

(tonnes NH3/year)

(tonnes/year)

(tonnes CO2 equivalents/year)

Reference

691

2.936

97.679

VBT standard

339

746

34.731

Based on the calculations it can be concluded that: ▪

The VBT standard scenario decreases the total emissions of ammonia in the manure processing chain with 51% compared to the reference scenario.

▪

Processing slurry and solid manure by co-digestion decreases the total emissions of methane in the manure processing chain with 75% compared to the reference scenario.

▪

Frequent collection of manure (and thus removal from the housing system) results in an average reduction of 9% ammonia emission in the housing systems and thus the farm region (Tilburg), as well as a 94% reduction of methane.

▪

Processing of manure into fertilizer pellets decreases ammonia emissions during application with 98%.

▪

Transport emissions of the reference and VBT scenarios are similar. In the reference scenario, larger volumes are transported over short distances, whereas in the VBT scenario smaller volumes of manure products are transported over longer distances.

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See figure S.1 for an overview of the ammonia emissions for all scenarios and their origin. Figure S.2 gives an overview of the greenhouse gas emissions for each scenario and their origin in CO2equivalents.

800 691

700

637

600 500 400

339

338

339

VBT standard

VBT 1 week storage

VBT 3 week storage

300 200 100 0 Reference Housing system

Figure S.1

External storage

Manure processing

Application

Domestic transport

New norm NB Foreign transport

Ammonia emissions (tonnes NH3/year) for all (sub)scenarios.

120000

97.679

100000

97.679

80000

60000

38.287

34.731

40000

30.456

20000

0 Reference Housing system

Figure S.2

VBT standard External storage

VBT 1 week storage

Co-digestion

Application

VBT 3 week storage

New norm NB

Domestic transport

Foreign transport

Greenhouse gas emissions (tonnes CO2 equivalents/year) for all (sub)scenarios.

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1 Introduction

1.1 Goal of the study The international company VBT has advanced plans to realise VTTI Bio-Energy Tilburg (VBT); a codigestion facility in Tilburg (The Netherlands), where biogas is produced and the residual product (digestate) is upgraded to fertilizer pellets and water. At this central location, 270k ton of (both solid and liquid) manure is supplied by pig farms within the region every year. Manure is collected every two weeks, which results in relatively fresh manure that will arrive at the central processing plant. The manure is processed by co-digestion and separation of the digestate. The liquid fraction is further processed through a Mechanical Vapor Recompression (MVR) evaporation process and Reversed Osmosis (RO) into dischargeable water. The solid fraction is further processed into fertiliser pellets and shipped to France and Southeast Asia. As manure is collected regularly from the pig farms and processed in a fully closed co-digestion plant, emissions of both ammonia and methane are expected to decrease through this processing facility. This expected decrease is due to a lower storage time in both the housing system and the manure storage, compared to the current situation. It is also expected that processing liquid manure into fertiliser pellets reduces transportation costs and emissions, since the volume of manure is drastically reduced.

Finally, emissions during application of fertiliser pellets are expected to be lower than liquid manure. The goal of this study was to evaluate what emission reductions can be obtained through processing of manure in the VBT processing plant. In order to do this emissions throughout the entire “manure chains” were evaluated for several scenarios. Starting from manure excretion in the housing system until application of manure products on the field. Furthermore, emissions during transportation of the products have been included as well.

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2 Method

The methods used for calculation of emissions from manure (processing) are the same as the one used in Gollenbeek et al. (2021). Emissions were calculated for 2 different scenarios with some sub scenario’s (see 2.2). Therefore, parts of the following text has been taken from that report.

2.1

Emission calculations

In order to determine the mass balances and emissions for the entire processing chain, a model study was used in which the quantities and composition of the manure (products) are determined. Emissions are calculated for each step in the manure processing process (see figure 2.1). The model is made up of different blocks, with each block representing a (processing) step. The model starts with the excretion of manure in the housing system and ends with the application of the manure products on the land. In this last step, emissions during application of manure products are included. Further soil processes are not taken into account as the complexity and uncertainties around soil processes cannot be integrated in this calculation model. Emissions that arise from manure have been included, as well as emissions arising from the use of fossil fuels.

Figure 2.1

Flow chart and schematic representation of the reference scenario (see 2.2).

The starting point of the model is the composition of slurry (or urine and faeces) directly excreted by the animal ('under the tail'). Nitrogen (N), phosphate (P2O5), carbon (C) and organic matter (OM) quantities and the subsequent emissions of methane (CH4), ammonia (NH3) and nitrous oxide (N2O) that are released are calculated. Appendix 1 describes the principles and inputs for the emission model

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for each scenario. The nitrogen containing emissions were calculated for each step in manure processing using emission factors from the NEMA model (Van Bruggen et al., 2019; Van Bruggen et al., 2021), which can be found in Appendix 1. When nitrogen emissions take place and biogas is formed, the compositions of total nitrogen and OM content in the manure change. For the nitrogen content in manure, the total ammoniacal nitrogen (TAN) content is corrected on the basis of the ammonia and nitrous oxide emissions that take place: the emitted nitrogen is subtracted from the amount of TAN in the manure. However, during the fermentation of manure, a different calculation method is used as the TAN/Organic nitrogen (N-org) ratio changes significantly during the fermentation process (Gollenbeek et al., 2021). Two processes influence this, and are calculated as follows: 1.

Nitrate + nitrite (NOx-N) emissions from combustion of biogas in CHP unit: It is assumed that through the formation of biogas in the digester, 1% emits as ammonia. The emission factor of NH3 during fermentation is calculated by dividing the total NH3 emission from biogas by the amount of TAN that is fermented. The result is the emission factor of NH3 (as % of TAN) which can be used to calculate the amount of NOx-N (kg/year) that is released from the biogas formed.

2.

Fixation of nitrogen in biomass (= formation of N-org from TAN): for this, it was calculated how much of the chemical oxygen demand (COD) has been removed by the formed methane. The COD value of methane is 4 kg O2/kg CH4, allowing the total COD removed to be calculated. Subsequently, the amount of N-org fixed in biomass was calculated by multiplying the total COD removed by the nitrogen share in the biomass, which was determined to be 13,0 g N/kg COD removed1. The amount of NOx-N emitted and N-org formed are subtracted from the amount of TAN in the digestate to calculate the TAN/N-org ratio in the digestate.

Methane production at a certain age of manure has been calculated with the following equation (1): (1) 𝐶𝐻4 (𝑡) = 𝐶𝐻4, 𝑚𝑎𝑥 × ( 1 −

1 ) 1 + 𝐾ℎ × 𝑡

Where: CH4 (t)

= Methane production at manure age in t days (in m3 CH4/kg OM)

CH4, max

= Maximum methane production at manure age t is 0 days (in m3 CH4/kg OM)

Kh

= hydrolysis constant (in d-1)

t

= Manure age (in days)

In order to map the total emissions of greenhouse gas emissions per scenario, the methane and nitrous oxide emissions were converted to CO2 equivalents2 using the following calculation rules (Myhre et al., 2013): 1 kg methane = 28 CO2 equivalents 1 kg nitrous oxide = 265 CO2 equivalents Energy consumption linked to the manure treatment processes were not included in total greenhouse gas emissions. Transport emission calculations Emissions related to transport were calculated based on the emission factors for different modes of transportation per tonne-kilometer (tkm). The emission factor indicates the expected emissions of transporting 1000 kg of weight over one kilometer with a specific mode of transportation. The emission factors used for this study are LCA transport emission factors; taken from the life cycle inventory database Ecoinvent 3.8 (Wernet et al., 2016). The modes of transportation considered in this study are (1) truck transport, (2) inland waterways transport (barges), and (3) sea transport (transoceanic ships). See appendix 1 for the principles and used emission factors. 1 2

https://emis.vito.be/nl/bbt/bbt-tools/selectiesystemen/wass/technieken/anaerobe-biologische-afvalwaterzuivering One CO2 equivalent is equal to the effect of 1 kg of CO2 emissions.

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In order to calculate the transport emissions, the emissions factors are multiplied by the appropriate amount of tkm per mode of transportation for each scenario. The emission factors are used to calculate NH3-emissions and greenhouse gas emissions (in CO2 equivalents). The CO2 equivalent transport emissions factors do not provide insight in the ratio of individual greenhouse gases (such as CO2, CH4, etc.) related to transport.

2.2

Scenarios

The emissions in this study have been calculated for two scenarios, with several variations. Below, a description per scenario is outlined. Reference scenario (1) In the reference scenario, slurry is stored under the slatted floor in conventional pig housing systems for an average of 90 days (thus manure is stored up to 6 months). The solid fractions used in this study were set to derive from housing systems that separate the liquid and solid fractions and store them separately in order to calculate emissions from the total volume of the solid fraction. However, in reality part of the solid fraction comes from central manure processing plants in the region of Tilburg. The pig housing systems that were used for emission calculations are based on the average housing systems in The Netherlands where slurry is collected. Based on this, 15% of housing systems were set on ‘regular housing system’ and 85% was set on ‘low emission housing system’ (Van Bruggen et al., 2021). For the housing systems that produce separate manure fractions, a reduction in ammonia emissions of 64% was calculated based on the RAV emission factor for a housing system with Vshaped belt under a slatted floor (RAV code D 3.2.163). The liquid fraction after separation remains on the farms and will be applied there or on farms in the neighborhood.

In the reference scenario, several assumptions have been made about the current (end) destination of the slurry and solid fractions of manure (see appendix 1 for details). For the slurry fraction of manure, it is assumed that 100% of this slurry is directly applied in the province of Zeeland. For the solid fraction of manure it is assumed that 50% of this fraction will be applied without any treatment. The other 50% of solid manure is composted before being exported to France. Of the untreated solids, it is assumed 20% is applied in Zeeland and 80% is applied in France. The transport emissions in this scenario do take into account the transport of the end products (solids and slurry) to their final destination. However, it does not take into account the transport emissions from farmer to the central composting facility and from farmer to the central manure processing facility. A variation of the reference scenario (scenario ‘new norm NB’) was included where it is assumed that all housing systems with slurry were equipped with air scrubbers, thus setting 100% of the slurry housing systems to ‘low emission housing system’. This was done as the province of North Brabant has stated that from January 2024 all pig housing systems should have a 85% ammonia emission reduction compared to the regular housing system4.

The VBT scenarios cannot be directly compared to the ‘new norm NB’ scenario, as the housing systems in the VBT scenarios are the same as the reference scenario.

VBT scenario (2) Here, manure (both slurry and the solid fraction) are processed by the VBT set-up through codigestion and processing into fertilizer pellets. The ratio of manure and co-products for the co-digester is 90/10. Slurry and solid fractions are stored in the same housing systems as the reference scenario. In the VBT scenario, the liquid fraction after separation remains on the farms (same as in the reference scenario). However, manure is stored up to 2 weeks and then transported to the central processing plant where it will be co-digested and further processed. As output, only fertilizer pellets 3 4

https://www.infomil.nl/publish/pages/130041/bwl_2008_11_v1.pdf https://noord-brabant.tercera-ro.nl/SiteData/9930/Publiek/BV00342/b_NL.IMRO.9930.IOVwijzregels2-on01_1.pdf

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are produced which are exported to either France or Vietnam. Emissions during application in these countries were included in the calculations. Two variations on this scenario were included in the study: sub scenario 2.2 and 2.3. In 2.2, storage of manure in the housing system was lowered to a maximum of 1 week. In sub scenario 2.3 the storage time was increased to a maximum of 3 weeks. The effect of these different storage times on ammonia and methane emissions were calculated. It is assumed that there is no effect on nitrous oxide emissions. For all variations of the VBT scenario it is assumed that the same amount of solids and slurry of the reference scenario will now be treated by VBT into fertilizer pellets. It is assumed that 25% of the pellets will be exported to France and 75% will be exported to Vietnam (see appendix 1 for details on transport distances). The transport of manure from farms and manure treatment facilities to VBT is taken into account, as well as the transport to France and Vietnam. The study does not take into account the truck transportation from VBT to the Barge Terminal of Tilburg, the truck transportation of co-products to VBT, the truck transportation of farmer to central manure treatment facility or the transportation from Ho Chi Minh City Port (Vietnam) to its final destination.

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3 Results

This chapter shows the results from the emission model per scenario. Table 3.1 shows the ammonia emissions for all scenarios. The ‘VBT 1 week storage’ scenario has the lowest ammonia emissions, with a total of 338 tonnes/year. This is a reduction of 51% compared to the reference scenario. However, differences in total ammonia emissions between the VBT scenarios are negligible (< 0,5%). This reduction is mainly caused by the emission reduction during application (as shown in figure 3.1). The VBT scenario only has fertilizer pellets as output, compared to a slurry-, solid-, and compost fraction as output of the reference scenario. Both the reference and VBT scenarios also have ammonium sulphate as output from the air scrubbers on the pig farms, but this fraction was not included in the study (same for both scenario’s). As application of these pellets causes far less emissions than the three manure fractions in the reference scenario, a reduction of 98% is obtained.

However, with the production of fertilizer pellets, the total volume and TAN-content of the manure product reduces significantly (whereas the total nitrogen is higher than the reference scenario), compared to the reference scenario: over 44.000 tonnes of pellets in the VBT scenario compared to 23.000 tonnes of manure fractions in the reference scenario, with a TAN-content of 86.000 and 1.153.000 kg/tonne, respectively. The lower amount of TAN in the VBT scenario thus decreases the ammonia emissions but also decreases the amount of available nitrogen for crops. Frequent collection of manure in the VBT scenarios show a slight reduction in ammonia emissions in the housing system (average of 9%). Table 3.1

Ammonia emissions for all (sub scenarios (tonnes NH3/year).

Scenario

Housing

External

Manure

system

storage

processing

Application

Domestic

Foreign

Total

transport

transport

Reference

227

74

4

305

16

67

691

VBT standard

206

74

6

5

12

36

339

205

74

6

5

12

36

338

206

74

6

5

12

36

339

173

74

4

305

16

67

637

VBT 1 week storage VBT 3 week storage new norm NB

800 691

700

637

600 500 400 339

338

339

VBT standard

VBT 1 week storage

VBT 3 week storage

300 200 100 0 Reference Housing system

Figure 3.1

External storage

Manure processing

Application

Domestic transport

New norm NB Foreign transport

Ammonia emissions (tonnes NH3/year) for all (sub)scenarios.

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The VBT scenarios cannot directly be compared to the ‘New norm NB’ scenario, as the latter is set to 100% low emission housing systems. If, however, the VBT scenarios would be set to these housing systems as well, then the emission reduction percentage would be the same as between the current reference and VBT scenarios. Nitrous oxide emissions that occur in the housing system and external storage do not change between the different scenarios (see appendix 2 for details on nitrous oxide emissions per scenario). When looking at total nitrous oxide emissions, the VBT scenarios shows a decrease of 22% which occur during application. As seen in figure 3.2, ammonia emissions play the biggest role in nitrogen emissions from manure, as the nitrous oxide share is on average 5% of total nitrogen emissions.

600000 518.427 473.952

500000

400000

300000

247.032

247.595

248.125

VBT standard

VBT 1 week storage

VBT 3 week storage

200000

100000

0 Reference

NH3-N

Figure 3.2

New norm NB

N2O-N

Nitrogen emissions from manure (tonnes/year) for all (sub)scenarios (excluding transport).

Table 3.2 shows the methane emissions for all scenarios. The ‘VBT 1 week storage’ scenario shows the lowest methane emissions, with a total of 593 tonnes/year. This is a reduction of 80% compared to the reference scenario. The VBT scenarios with a manure storage of 2 and 3 weeks, show a reduction of 75% and 70%, respectively compared to the reference scenario. This reduction is caused by the emission reduction in the housing system (as shown in figure 3.3). Through quick removal of manure in the storage under the slatted floor, methane emissions through breakdown of organic matter is drastically reduced. As the manure in the VBT scenario is then processed, emissions of methane further down the chain are avoided. Fully removing manure from the storage, however, can be practically challenging in conventional farms. Table 3.2

Methane emissions from manure for all (sub)scenarios (tonnes/year).

Scenario

Housing system

External storage

Co-digestion

Total

Reference

2.787

148

VBT standard

184

148

414

746

VBT 1 week storage

100

72

422

593

VBT 3 week storage

263

202

407

873

New norm NB

2.787

148

2.936

2.936

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3500 2.936

3000

2.936

2500

2000

1500

1000

873

746 593

500

0 Reference

VBT standard Housing system

Figure 3.3

VBT 1 week storage External storage

VBT 3 week storage

New norm NB

Co-digestion

Methane emissions from manure (tonnes/year) for all (sub)scenarios.

Through the entire chain, from excretion of manure in the housing system to application of products, emission of greenhouse gasses occur. These consist of primarily methane and nitrous oxide from manure, but emissions during transport are included as well. Figure 3.4 shows the total greenhouse gas emissions, converted in CO2 equivalents (see Appendix 2 for an overview of these emissions).

120000

97.679

100000

97.679

80000

60000

38.287

34.731

40000

30.456

20000

0 Reference Housing system

Figure 3.4

VBT standard External storage

VBT 1 week storage

Co-digestion

Application

VBT 3 week storage

New norm NB

Domestic transport

Foreign transport

Greenhouse gas emissions (tonnes CO2 equivalents/year) for all (sub)scenarios.

The figure shows a significant reduction in greenhouse gasses in the housing system in the VBT scenarios, compared to the two reference scenarios. Co-digestion of manure does lead to an additional link of emissions in the chain, however the reduction caused in the housing system amply compensates this. The VBT scenario with a storage time of 1 week causes the lowest greenhouse gas emissions, with a little over 30.000 tonnes CO2-equivalents. This is a 69% reduction compared to the reference scenario. However, the VBT standard and 3 week storage scenarios have similar emissions (34.000 and 38.000 tonnes, respectively).

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4 Discussion

Nitrous oxide emissions Nitrous oxide emissions that occur in the housing system and external storage do not change between the different scenarios, as nitrous oxide emissions from manure depend largely on the aerobic and anaerobic conditions of the stored manure, and are less influenced by the storage time differences used in this study (Van der Hoek & Van Schijndel, 2006). Therefore, emission factors for nitrous oxide differ between type of manure (liquid or solid) but do not change between housing systems and storage times. For this reason, results show no difference between the different variations of scenarios, only between the reference and VBT scenario. In reality, differences of nitrous oxide emissions between different storage times could occur but more research on these processes needs to be done. Nitrous oxide emissions between the VBT scenarios (of 1, 2 or 3 weeks of storage) will show minor differences. Housing systems and manure removal With regards to the housing system, it has been assumed that the V-shaped belt under a slatted floor (RAV code D 3.2.16) was used to obtain a urine and faeces fraction. This system is still rare and may not be built in the province of North Brabant, because the emission reduction is less than the obliged 85%.

However, the V-shaped system in both scenarios was used because figures for the individual fractions (liquid and solid) were known. So the differences in emissions between the two scenarios have been correctly determined. The system was also chosen because fresh faeces (necessary for modelling the age of manure) will become available and because it can be expected that such primary separation systems will be built more in the future. Ammonia emissions during production of fertilizer pellets In the VBT scenarios where the digestate is further processed into fertilizer pellets, the emission of ammonia that occurs during the production process is set on 5,9 tonnes NH3/year. This is the maximum permitted emission for the VBT facility. However, in reality emissions are expected to be lower as it is estimated that 1% of nitrogen emits as ammonia during the production of a fertilizer pellet and the VBT facility captures this emission with an air scrubber with a 98% efficiency. Emissions during application During the last step of each scenario, emissions of NH3 and N2O during application of the manure products are calculated. This is done in the same way as the previous steps in the model: the nitrogen emissions are calculated with a specific emission factor, taken from Van Bruggen et al. (2021).

However, specific emission factors for each manure product, such as a fertilizer pellet, have not yet been determined which creates uncertainty on the amount of nitrogen emissions that occur during application. Through expert judgment, emission factors for NH3 emissions for specific manure products have been used for this study (Van Dijk et al., 2020). Even less is known on emissions of nitrous oxide during application and Van Bruggen et al. (2019; 2021) use the same emission factor for all manure products or fertilizer products, which have been used in this study. This increases the uncertainty of the emissions during application that have been calculated. In the reference scenarios, one of the manure products that was included was the faeces fraction of pig manure. Emissions from this fraction were calculated for the housing and storage systems and application on the field, assuming the same conditions for 100% of the solid fraction. However, in reality part of the faeces fraction comes from pig farms and the other part comes from central manure processing plants in the region of Tilburg. Differences in nitrogen content between these fractions can occur, which influences the nitrogen emissions (as these are based on the total nitrogen or TANcontent).

Furthermore, the solid fractions from manure processing plants are further processed through biodigestion or composting, resulting in manure products that could have lower emissions during application than application of the solid fraction. If these differences are considered, variation in total nitrogen emissions from the solid fractions are likely to occur.

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In the VBT scenarios, emissions during application were only considered for the produced fertilizer pellets, as this is the only output produced by the VBT facility in these scenarios. However, all scenarios (reference and VBT scenarios) include housing systems with air scrubbers, which results in the production of ammonium sulphate on the farms. This product can be applied as a fertilizer and will emit ammonia during application. The production of ammonia sulphate and resulting nitrogen content of this product were not included in this study, but do play a (minor) role in the total ammonia emissions from these scenarios. For all scenarios, emissions during application of the manure products have been calculated, including application in France and Vietnam. However, the emissions factors used in this study are linked to specific application techniques (see appendix 1) which might differ from country to country. The actual emissions linked to application of the manure products thus depend on which application techniques are used in the countries where the manure products are exported to and can differ from the emissions presented in this study. Ammonia emissions during transport For the calculation of emissions during transportation of manure (products) emission factors from the LCA Ecoinvent database were used.

As an LCA considers the environmental impacts of the whole life cycle of transport, it not only considers emissions related to the combustion of fuel (which included CO2- and NOx emissions) but also emissions associated with the production and maintenance of the vehicle, roads, etc. During these processes, emissions of NH3 occur as well, which for this study results in greenhouse gas, as well as ammonia emissions during transport.

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5 Conclusion

The goal of this study was to determine the effects of treating manure in the VBT facility on ammonia and greenhouse gas emissions. Table 5.1 shows a summary of the results for the reference and VBT standard scenario. Table 5.1

Total emissions of the reference and VBT scenarios.

Scenario

Ammonia emission

Methane emission

Greenhouse gas emission

(tonnes NH3/year)

(tonnes/year)

(tonnes CO2 equivalents/year)

Reference

691

2.936

97.679

VBT standard

339

746

34.731

Based on the results, it can be concluded that: ▪

The VBT standard scenario decreases the total emissions of ammonia in the manure processing chain with 51% compared to the reference scenario.

▪

Processing slurry and solid manure through co-digestion decreases the total emissions of methane in the manure processing chain with 75% compared to the reference scenario.

▪

Frequent collection of manure (and thus removal from the housing system) results in an average reduction of 9% ammonia emission in the housing systems and thus the farm region (Tilburg), as well as a 94% reduction of methane in the housing systems.

▪

Processing of manure into fertilizer pellets decreases ammonia emissions during application with 98%.

▪

Transport emissions between reference and VBT scenarios are similar. The reference scenarios transport larger volumes of manure (products) over shorter distances, whereas the VBT scenarios transport smaller volumes of manure products over longer distances.

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Literature

Bruggen, C. van, A. Bannink, C.M. Groenestein, J.F.M. Huijsmans, L.A. Lagerwerf, H.H. Luesink, S.M. van der Sluis, G.L. Velthof en J. Vonk. 2019. Emissies naar lucht uit de landbouw in 2017. Berekeningen met het model NEMA. Wageningen, WOT Natuur & Milieu, WOt-technical report 147. Bruggen, C. van, A. Bannink, C.M. Groenestein, J.F.M. Huijsmans, L.A. Lagerwerf, H.H. Luesink, M.B.H. Ros, G.L. Velthof, J. Vonk en T. van der Zee. 2021. Emissies naar lucht uit de landbouw berekend met NEMA voor 1990-2019. Wageningen, WOT Natuur & Milieu, WOt-technical report 203. Dijk van, W. van, R. Postma en J. Roefs. 2020. Landbouwkundige waarde mestbewerkingsproducten; Aanvoer van nutriënten en organische stof met geselecteerde product-markt-combinaties. Wageningen Research, Rapport WPR-1012. Gollenbeek L.R., J.P.B.F. van Gastel, F.A.M. Casu, N. Verdoes. 2021. Emissies en kosten van verschillende scenario’s voor verwaarding van varkensmest; NL Next Level Mestverwaarden. Wageningen Livestock Research, Openbaar Rapport 1331. Groenestein, K., R.W. Melse, J. Mosquera, M. Timmermans. 2020. Effect mestvergisting op de emissies van broeikasgassen uit mest van melkvee: een literatuur- en scenariostudie. Wageningen, Rapport 1235. Hoek, K.W. van der, M.W. van Schijndel. 2006. Methane and nitrous oxide emissions from animal manure management, 1990 – 2003.

Background document on the calculation method for the Dutch National Inventory Report. RIVM report 680125002/2006 Myhre, G., D. Shindell, F.M. Bréon, W. Collins, J. Fuglestvedt, J. g, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang. 2013. Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Wernet, G., Bauer, C., Steubing, B., Reinhard, J., Moreno-Ruiz, E., and Weidema, B., 2016. The ecoinvent database version 3 (part I): Overview and methodology. The International Journal of Life Cycle Assessment 21: 1218–1230.

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Annex 1 Principles for the emission calculations

In this appendix, the principles for the calculation of the manure flows (table A1.1 and A1.2) and emissions during transport (table A1.3) are given for both scenarios. These were used as input for the emission calculation model. Table A1.1

Principles for the reference scenario.

Manure in the housing system BMP = 0,29 m3 CH4/kg OS present Kh = 0,009276 Ratio volume % CH4-CO2 = 85-15

Groenestein et al., 2020

Conversion N-org in N-NH4 = 30% Emissions manure and solid fraction

Weighted average between regular and low emissions housing systems

NH3-N = 12,2% of TAN

Van Bruggen et al., 2019; Slurry

NH3-N = 14,4% of TAN

Van Bruggen et al., 2019; Solid

N2O-N = 0,20% of total N

Van Bruggen et al., 2019; Slurry

N2O-N = 0,50% of total N

Van Bruggen et al., 2019; Solid

Application of manure (products) Conversion N-org in N-NH4 = 0%

Assumption that all mineralization has occurred after digestion

Emissions manure/slurry NH3-N = 19,8% of TAN

Van Bruggen et al., 2021

N2O-N = 0,003% of total N

Van Bruggen et al., 2021

Emissions solid fraction NH3-N = 56,8% of TAN

Van Bruggen et al., 2021

N2O-N = 0,001% of total N

Van Bruggen et al., 2021

Emissions compost NH3-N = 5% of TAN

Van Bruggen et al., 2021

N2O-N = 0,008% of total N

Van Bruggen et al., 2021

Emissions N-concentrates NH3-N = 1,5% of TAN

Van Dijk et al., 2020

N2O-N = 1,3% of total N

Bruggen et al., 2019

Table A1.2

Principles for the Design Menu scenario.

Manure in the housing system BMP = 0,29 m3 CH4/kg OS present Kh = 0,009276 Ratio volume % CH4-CO2 = 85-15

Groenestein et al., 2020

Conversion N-org in N-NH4 = 1%, 2%, 3%

Manure storage of respectively 1, 2, and 3 weeks

Emissions manure/slurry NH3-N = 10,4% of TAN

Slurry; 2 weeks storage

NH3-N = 10,3% of TAN

Slurry; 1 week storage

NH3-N = 10,4% of TAN

Slurry; 3 week storage

NH3-N = 14,4% of TAN

Van Bruggen et al., 2019; Solid Vertrouwelijk Wageningen Livestock Research Rapport

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N2O-N = 0,20% of total N

Van Bruggen et al., 2019; Slurry

N2O-N = 0,50% of total N

Van Bruggen et al., 2019; Solid

Co-digestion of manure Conversion N-org in N-NH4 = 61% Ratio volume % CH4-CO2 = 60-40

Groenestein et al., 2020

Loss of CH4 in co-digester = 3%

Assumption

Loss of CH4 in CHP unit = 1%

Assumption

Application of manure (products) Conversion N-org in N-NH4 = 0%

Assumption that all mineralization has occurred after digestion

Emissions fertilizer pellets NH3-N = 5% of TAN

Van Dijk et al., 2020

N2O-N = 0,008% of total N

Van Bruggen et al., 2019

Table A1.3

Principles for emission calculation during transportation.

Truck type used: Lorries, >32 ton, EURO6 Distances Average distance domestic truck transport = 113 km

Average distance calculated from Tilburg to Zeeland

Average distance foreign truck transport = 725 km

Average distance calculated from Tilburg to Vesdun (France)

Average distance inland waterways transport = 90

Average distance calculated from Tilburg to

km

Rotterdam port

Average distance sea transport = 16753 km

Average distance calculated from Tilburg to Ho Chi Minh (Vietnam)5

Emission factors Truck transport NH3 = 8,56E-07 kg NH3/tkm CO2 = 8,64E-02 kg CO2-eq./tkm Inland waterways transport NH3 = 3,03E-07 kg NH3/tkm CO2 = 4,52E-02 kg CO2-eq./tkm Sea transport NH3 = 5,22E-08 kg NH3/tkm CO2 = 1,13E-02 kg CO2-eq./tkm

5

Routescanner – Make better container shipping decisions

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Appendix 2 Overview of emissions

Table A2.1

Nitrous oxide emissions for all scenarios (tonnes N2O/year).

Scenario

Housing

External

system

storage

Reference

12,9

VBT standard

12,9

VBT 1 week storage VBT 3 week storage new norm NB

Table A2.2

Application

Total

7,8

6,23

26,9

7,8

0,32

21,0

12,9

7,8

0,32

21,0

12,9

7,8

0,32

21,0

12,9

7,8

6,23

26,9

Greenhouse gas emissions from manure and transportation for all scenarios (tonnes CO2 equivalents/year).

Scenario

Housing

External

Co-

system

storage

digestion

Reference

81.473

6.205

VBT standard

8.580

6.205

VBT 1 week

6.225

4.061

10.796

7.717

81.473

6.205

Application

Domestic

Foreign

transport

transport

Total

1.615

1.582

6.768

97.679

11.579

84

1.302

6.982

34.731

11.802

84

1.302

6.982

30.456

11.406

84

1.302

6.982

38.287

1.651

1.582

6.768

97.679

storage VBT 3 week storage new norm NB

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