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Workshop “Straw-Combustion - Economic Opportunities for the Serbian Agro-

Industry”Belgrade, 22nd April 2015

Straw Residual Potential in Serbia for Energy Use

-taking into account the soil balance, economic aspects and technical requirements on the supply chain-

Martinov, M., Djatkov, Dj., Golub, M., Viskovic, M.Faculty of Technical Sciences, Novi Sad

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OUTLINE

1. INTRODUCTION

2. POTENTIALS OF BIOMASS IN SERBIA

3. OWN INVESTIGATIONS

4. PROCUREMENT, SUPPLY CHAINS, COSTS

5. SUSTAINABILITY ISSUES

6. CONCLUDING ISSUES

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STAGES OF TECHNOLOGY MATURITY

1. Laboratory level, tests positive.

2. Prototype level, confirmed results.

3. Demonstration plant level, approved results.

4. Commercial level (even better few years tested in practice).

FOR SERBIA IS ACCEPTABLE ONLY THE FOURTH ONE!!!

1. INTRODUCTION

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October 2014

September 2014

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Some examples of crop residues use

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Examples of contemporary heat generators produced in Serbia

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Many open questions:

1. Mature biofuel technology?

2. Realistic feedstock potential based on sustainable approach, soil fertility preservation?

3. Proper harvest and storage technology of corn stover?

4. Costs of feedstock?

5. Supply security?

6. Environmental impact, including GHG reduction?

7. Etc.

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2. POTENTIALS OF BIOMASS IN SERBIA

Source Biomass Hydro Solar Geothermal Wind Σ

% 62 14 15 5 4 100 Мtое 3.3 1.7

(0.8+0.9) 0.6 0.2 0.2 6.0

Source: National renewable energy action plan of the Republic of Serbia, 2013

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We consider following potentials:

1. Theoretical.

2. Harvestable (technical).

3. Sustainable.

4. For energy.

5. Specific for large consumers due to use of big bales, plots over 5 ha.

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Sustainable potential, 1,000 t

Energy potential, 1,000 t Crop T Acreage,

1,000 ha

Big farms, 1,000 t

S&M farms, 1,000 t Big farms S&M

farms Big farms S&M farms

Wheat 797 178 619 374 1,080 355 970 Ray ─ 8.6 0.8 7.8 2 14 2 14 Barley ─ 135 46.6 88.4 80 154 80 138

s 130 s 735 s 130 s 660 Corn 1,358 133 1,225 c 15 c 1,200 c 15 c 1,200 Sunflower ─ 160 74.9 85.1 0 0 0 0 Soybean 83 54.8 28,2 105 50 105 50 Oil rape 1.4 0.7 0.7 2 2 2 2

708 3,235 689 3,034 Total 3,943 3,723

According to our calculations, potentials of crop residues are lower, about 1.3 M toe

T– trend of growing acreage, S&M– small and medium farms, s– stover (for the S&M not calculated harvest of on field remained mass, only if universal harvester is used), c– cobs (harvest with picker-husker, typical for S&M farms and seed production)

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For each crop were taken samples, total above ground mass, from three different locations, five per plot, in the full maturity of grain, harvest time in 2011 and 2012. Weather conditions in 2011 were identified, as very dry, although such definition is common for the last decade. In 2012 they were extremely dry.

The plants were separated into fractions as further described, moisture content measured, mass of fractions, and their relative yield (relative to grain yield) and harvest index calculated.

The residual mass that is expected to be harvested, depending onharvest procedure, is assigned as harvestable mass. On field remained mass of crop residues is calculated by subtracting harvestable from total mass of above ground residues.

The criterion for erosion protection was the amount of on field remained biomass. It should cover at least 30 % of surface, i.e. 1.1 Mg of flat small grain residue equivalent ASAE EP291.3 (Anonymous, 2005).

Tillage losses and weathering impact were calculated based on Hickman and Schoenberger (1989) procedure.

2. OWN INVESTIGATIONS

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Corn

Harvest, typically, starts in the second half of September, for hybrids of FAO group 400, and finishes at the end of November, for the hybrids of FAO group 700.

The samples were taken on farms that apply high level of agro technology. The row distance on all plots was 0.7 m, and crop density 60,000 to 70,000 plants per ha, as common in the region.

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The calculation of harvestable mass is performed based on harvest procedures, described in Golub et al. (2012). This includes harvested fractions and harvest losses. Single-pass procedure, described by some authors, is followed by productivity reduction up to 50 % (Shinners et al., 2012). The stover harvest procedures and assumed losses are:

Two-pass harvest. Grain harvest by combine with snapper–head and integrated shredder-cornrower described in Straeter (2011) and Shinners et al. (2012). The stover is picked-up from windrow by round or big rectangular baler. Cutting height is 0.2 m. Percentages of harvested fractions are 70, 90 and 90 %, for stalks+leaves, cobs and husks respectively, with additional baling losses of 20 %.

Multi-pass harvest. This is conventional stover harvest procedure. As previous but combine harvester is equipped with integrated stover shredder. It is followed by raking, forming windrow and baling. The cutting height is 0.2 m. Percentages of harvested fractions are 70 % for stalks+leaves and 40 % for cobs and husks combined, with additional baling losses of 20 %.

Ears harvest. For the harvest is used picker-husker. All cobs are available after natural drying and threshing in yard, without losses.

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The samples of eight varieties of wheat and six of soybean were collected.

Based on the results for moisture content, yield of each part of the plant was calculated. Diagrams representing cumulative mass of stalks along its height were made. These diagrams were used for determination of stalks residues remaining on a field after harvest, stubble, depending on cutting height.

Wheat and soybean

Wheat and soybean straw segments

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2011

2012

Range and average of relative yields of stover fractions, 1– lowest 0.2 m of stalks, 2– stalk+leaves, 3– cobs, 4– husks, 5– total aboveground residues, 6– sum of 2, 3 and 4

Harvest proc.

Harvestable mass Remained mass

Mg ha–1RY, % Mg ha–1 PTM, %

2011

1 51 5.5 53 4.8

2 41 4.5 43 5.6

3 18 1.9 19 8.4

2012

1 72 3.8 53 3.3

2 59 3.1 43 4.0

3 22 1.1 16 6.0

RY– relative yield (to grain) PTM– percentage of total above ground mass

Corn

High dissipation

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For both seasons, the percentage of harvestable mass related to total was same for the harvest procedures 1 and 2, 53 and 43 % respectively, but harvestable mass considerably lower, 5.5/3.8 and 4.5/3.1 Mg ha–1. Reduction of harvestable mass was, due to weather conditions, 31, 31 and 42 %, and on field remained mass 29, 32 and 28 %, for harvest procedures 1, 2 and 3, respectively.

In all cases the on field remained residual biomass can ensure, by using of adequate tillage, wind erosion protection!

The obtained data can be used for solving some of defined problems!

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Parameter 2011 2012

Grain yield, Mg ha–1 6.9 5.1

Harvest index 0.48 0.49

Mass of aboveground residues, Mg ha–1 7.6 5.2

Mass of harvestable straw, Mg ha–1 3.8 2.1Percentage of harvestable mass in comparison with mass of grain*, % 55.5 40.0

Percentage of harvestable mass in aboveground residues, % 50.0 39.3

On field remained mass, Mg ha–1 3.8 3.1

Percentage of on field remained mass in aboveground residues, % 50.0 60.7

Wheat, cutting height 15 cm Soybean, cutting height 7.5 cmParameter 2011 2012

Grain yield, Mg ha–1 4.7 2.7

Harvest index 0.47 0.41

Mass of aboveground residues, Mg ha–1 5.3 3.8

Harvestable mass*, Mg ha–1 2.1 1.3Percentage of harvestable mass in comparison to mass of grain*, % 44.7 48.1

Percentage of harvestable mass in aboveground harvest residues, % 39.6 34.2

On field remained mass, Mg ha–1 3.2 2.5

Percentage of on field remained mass in aboveground residues, % 60.4 65.8

Mg is correct, according to IS, designation for tone

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Decrease of harvestable straw mass for wheat was 45 %, and on field remained mass 18 %.

For soybean harvestable straw mass decreased 37 %, and on filed remained mass 20 %.

Crop Soybean WheatSeason 2011 2012 2011 2012On field remained mass DM, Mg ha–1 2.1 1.7 2.5 2.1

On field remained mass of crop residues after application of chisel ploughing

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1. Experimental determination of biogas yield and methane potential

BG yield= 387.8 ml/gDM (SD=15.4)BG yield= 406.5 ml/gODM(SD=16.1)CH4 = 187.4 ml/gDM (SD=11.8)CH4 = 196.4 ml/gODM (SD=12.4)CH4 = 48.3 % (SD=1.3 %)

Good yield, too long retention time!

2. Improvement of corn stover harvest and storage

3. Development of corn stover pelletizing

ONGOING R&D ACTIVITIES

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4. PROCUREMENT, SUPPLY CHAINS, COSTS

Procurement, provision, consists of:

1. Harvest, collection, of crop residues on the field.2. Loading of feedstock to the transport vehicle.3. Transport to the primary storage.4. Unloading and storing.

For the bigger users there are additional activities:5. Loading to the long distance vehicle.6. Transport to the plant storage. 7. Unloading and storing.8. Exemption from storage, pre processing, feeding the plant.

Simplified it can be split into harvest and logistic.

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corn silagecombine harvester

grains

bales

bales

pellets

grindedmaterial

self propelled mower bales storage

forage harvesterlow storage

bales storage

pellets silage or floor storageself propelled pellet mashine

grain

straw

swat drying

self propelled straw harvester

Straw harvest and logistic solved

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Some examples of new development of corn stover harvest equipment

Corn stover harvest and logistic still under development

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Newest development of headers with chopper and windrowers

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Storage

Supply security is very important issue, especially for big consumers.

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Costs of biomass

For the big consumers it is needed to add costs for transport and others. These depend on transport distance and are, additionally, between 25 and 30 %.

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5. SUSTAINABILITY ISSUES

SOIL IS NON-RENEWABLE RESOURCE, SOIL FERTILITY MUST BE PRESERVED

ISSUES RELATED TO THE SOIL FERTILITY PRESERVATION, AMMELIORATIONWIND AND WATER EROSION ELIMINATION OR MITIGATION.VALUE OF NUTRIENTS AND SOM/SOC OFFTAKE (mostly concentrated in root and rhizosphere).

PRESERVATION OF SOIL FERTILITY

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EXAMPLES OF LITERATURE SOURCES

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Modeling of Soil Organic Carbon Stocks (0 to 20 cm depth) at Different Levels of Straw Removal at Experimental Sites

EXAMPLE OF CROP SELECTION AND CROP ROTATION AS A TOOL FOR SOC INCREASE

excerpt from literature source 1

In every case should be consulted expert for agropedology to propose measures for soil fertility preservation.

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VERY IMPORTANT ISSUE IS TO ENABLE SIGNIFICANT REDUCTION OF CO2eq REDUCTION

This issue is defined by articles 17 to 21 of Directive 2009/28/EC and Directive 2009/30/EC, as prerequisite of being eligible for subsidies.

From 2018 this reduction should be at least 60 %, in comparison with emission of fossil fuels (83.8 gCO2e/MJ).

Emissions are related to feedstock supply and its processing to fuel.

LIMIT OF EMISSIONS

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Very recent publication!

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One liter of fossil fuels is 83.8 gCO2e/MJ. For the required reduction of 60 % (after 2018) it is 33.5 gCO2e/MJ.

LCB production, ethanol 21 MJ/l.

3.8 kg of bone dry stover is needed to get 1 L of ethanol.

All operations, from harvest to processing plant feeding - chopped material.

OUR PRELIMINARY CALCULATION OF GHG EMISSIONS

-only from feedstock supply-

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75%55%36%25.118.612.0Round bales 1.8x1.576%56%37%25.518.912.3Big rectangular bales98%72%46%32.824.115.4Chopped

120 km72 km24 km120 km72 km24 km

Share in max permitted emission, %Emission gCO2e/MJ

Reduced yield (extreme drought)

Common yield

65%49%33%21.916.411.0Round bales 1.8x1.566%50%33%22.216.711.2Big rectangular bales81%59%38%27.219.912.6Chopped stover

100 km60 km20 km100 km60 km20 km

Share in max permitted emission, %Emission, gCO2e/MJ

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6. CONCLUDING ISSUES

Many potential investors in heat generators for crop residues,

one potential investor for LCB plant, based on crop residues,

and few potential users of crop residues as co-substrate for biogas production,

waiting for answers and our assistance.

This is the last slide of the presentation!