COMPARING YIELDS OF MISCANTHUSX GIGANTEUS AND SORGHUM

BICOLOR FOR BIO-METHANE AS PROSPECTIVE ENERGY PLANTS

Pavol Porvaz

The qualitative parameters were studied as follows:Chemical analyses of biomass before and after fermentation:- chemical oxygen demand [mg l-1] – photometrically- sulphur content [mg l-1] – photometrically- total nitrogen content [mg l-1] – photometrically- dry matter content [%] – gravimetrically

Measured components of biogas using MADUR gas analyzer:- methane [% vol.] – by infrared dual-beam sensor- carbon dioxide [% vol.] – by infrared dual-beam

sensor- oxygen [% vol.] – electrochemically- hydrogen sulphide [ppm vol.] – electrochemically

2

Verification of prospective types of energy crops Miscanthus x giganteus and Sorghum bicolor variety Sole on extraction of bio-methane at Experimental workplace in Milhostov, Agroecology Research Institute in Michalovce, dry fermentation method in semi-operational conditions of Experimental workplace Kolíňany SUA in Nitra.

Localization of Experimental workplace Milhostov

3

Miscanthus x giganteus

Plant characteristics:Øbotanically it belongs to the family of the Poaceae and the Andropogoneae; it is a perennial plant of C4 type

Øproduction potential under favorable conditions is over 30 t ha-1

dry matter in terms of irrigation to 40 t ha-1 dry matter

Growing conditions – soil-climatic conditions:Ølighter structural soils (loam till loamy-sand soils)Øthe transpiration coefficient is about 250 l kg-1 of dry matter and

it is a value between sorghum (200 l kg-1 DM) and maize (300 l kg-1 DM)

Øfor 40 t ha-1 dry matter yield 1000 mm of water are needed

Øresults from field treatment of the NAFC – Agroecology Research Institute Michalovce (average 2004 and 2005 years = 38.8 t ha-1) verify suitability of Miscanthus species for cultivating for energy purposes

4

Miscanthus substrate adjusted to the dry fermentation process before to the test

5

Miscanthus x giganteussmall plot field experimentswere based on in vitroseedlings on Experimentalworkplace in Milhostov andGleyic Fluvisol by randomarrangement.

6

Course of production of biogas and methane content by fermentation of substrate mixed Miscanthus x

giganteus – 1. cycle

►Production of biogas on adaily basis for measuring thetemperature and bio-methane content of biogas.

► The bio-methane content onthe third day of fermentationreached a production curve of60 % or more until the end ofthe cycle, with the fermentertemperature at 39-41 °C curve.

0

10

20

30

40

50

60

70

80

90

100

110

26.02.20

1327.02.20

1328.02.20

1301.03.20

1302.03.20

1303.03.20

1304.03.20

1305.03.20

1306.03.20

1307.03.20

1308.03.20

1309.03.20

1310.03.20

1311.03.20

1312.03.20

1313.03.20

1314.03.20

1315.03.20

1316.03.20

1317.03.20

1318.03.20

1319.03.20

1320.03.20

1321.03.20

1322.03.20

1323.03.20

1324.03.20

1325.03.20

13

Metán

,%,Prod

ukcia,l/de

ň,Tep

lotavoferm

entore,st.C

dni

metán

produkcia

teplotavofermentore

7

The flow of methane, carbon dioxide, oxygen and hydrogen sulphide in biogas – 1. cycle

The tested substrate showed low hydrogen sulphide production during fermentation – in average of 10.92 ppm

► Biogas must be modified before use as fuel in a gas engine.

8

The average values of Miscanthus x giganteus monitored parameters –

1. cycle (from 4th to 29th day)

MaterialCH4 H2S CO2

Prod. BP

obj. % ppm obj. % l/day

Substrate (fermentation + Miscanthus x

giganteus)

58.67 10.07 33.33 39.13

The average values of Miscanthus x giganteus monitored parameters –

1. cycle

Parameter Unit

Samples of substrates

Inputs values

pH - 4.799

temperature °C 30.4

TS % 33.57

VSS % 31.54OTS %TS 94.23COD mg/l 125 500VFA mg/l 4 000Ekv. acetic acid mg/l 2 000Ntot mg/l 9 540SO4

2- mg/l 759

where: TS – dry matter content; OTS – organic dry matter; VSS – losses by ignition; COD – dichromate value; Ntot – total nitrogen content; SO4

2- - sulphate anions

9

Dipl. Ing. Gábrš – grower of Miscantus x giganteus – locality Pukanec Štiavnické Hills– area 13 hectares

10

60 liter containers containing Miscanthus x giganteus cut phytomas and Sorghum bicolor variety Sole depressed, airless, prepared for dry fermentation experiment.

11

ThestandofSorghumbicolorvarietySole–Milhostov- ExperimentalworkplaceofNAFC– AgroecologyResearchInstituteMichalovce

►Harvest of silage and Sorghum bicolorfor extraction of bio-methane Sole variety– at dry matter content 30 – 35 %.

► At dry matter content 30 – 35 % theplants of Sorghum bilocor variety Sole washarvest for extraction of bio-methane.

12

The course of biogas production and methane content in fermentation of silage from sorghum - variety Sole

►Process was realized from 10October to 27 October 2013, i.e. for18 days. Throughout the cycle,biogas production in terms of l.d-1,biogas composition and percolatepH was evaluated daily.

► The methane content increasedon the 4. day of fermentation over53.46%. Starting on the 6. day, themethane value was higher than 60% and values close to 60 % werereached until the end of theexperiment.

► The highest methane content ofmore than 62.02 % was achievedalready on the 6. day of theexperiment.

13

The course of biogas production and methane content at fermentation of sorghum silage – variety Sole

►During fermentation process, tested substrate shown low value of hydrogen sulphide output – in average 12.65 ppm.

► Such bio-gas, before its using as fuel for gas-engine, isn’t needful to adjust.

14

During an 18-day experiment inexperimental fermenter, the totalproduction of biogas from 6 kg ofsorghum variety Sole was mixedwith 13 kg of 571.4 l liquidsubstrate, which represents inaverage daily production of 29.986 lper day.

►The dry matter (DM) content ofthe feedstock, at average dryweight of 25.62 %, was 4.867 kg.

►Production of biogas, calculatedon a dry weight basis, was 117.4 l /kg of DM substrate.

15

The average values of monitored parameters of Sorghum bicolor variety

Sole - (from 4th to 18th day)

Material

CH4 H2S CO2Prod.

BP

obj. % ppm obj. % l/day

Substrate (fermentation +Sorghum)

60.12 10.26 25.944 29.986

Average values of monitored parametersand the chemical composition of the

substrates

Parameters Unit Samples of substrates

EntrypH - 8.174temperature °C 12.1TS % 19.39VSS % 16.9OTS %TS 87.74COD mg/l 332 500VFA mg/l 4 400Ekv. acetic acid mg/l 2 200Ntot mg/l 16 975SO4

2- mg/l 2 385

where: TS – dry matter content; OTS – organic dry matter; VSS –losses by ignition; COD – dichromate value; Ntot – total nitrogen content; SO4

2- - sulphate anions

16

The substrate Sorghum bicolor variety Sole - fermentation before fermenting.

Sorghum bicolor variety Sole adapted to the dry fermentation process before starting the experiment.

17

The stand of Sorghum bicolor for bio-methane production –interest of farmers from South-east Slovakia.

18

Ø "Dry fermentation" technologies can be used for energy recovery of biomasswith dry matter 20 up to 60%.

Ø The optimal dry matter content usually varies between 30 and 35% independence on the biomass to be processed.

Ø Based on the results obtained, it can be concluded that the tested biomassconsisting of both Chinese and sorghum are suitable for biogas productionby anaerobic dry fermentation technology.

Ø The biogas production in Sorghum bicolor variety Sole, calculated on a dryweight unit, was 117.4 l / kg DM substrate.

Ø Miscanthus x giganteus biogas production per dry unit was 68.433 l / kg DMsubstrate.

Ø By comparing the biogas yield of 1 kg of dry matter of the substrates beingtested, sorghum is the most advantageous sugar crop for biogasproduction, but it is a one year old plant.

Ø The Chinese as a biogas plant is very interesting from the point of view ofbiogas production, especially the duration of 20 - 25 years on the site, whichadvises her between prospective crops for biogas stations.

CONCLUSION

19

Thank you very much for your

attention.