Lignotselluloossetest jäätmetest vedela biokütuse tootmiseks kemikaalivaba eeltöötlusmeetodi väljatöötamine ja optimeerimine

A Thesis for applying for the degree of Doctor of Philosophy in Engineering Sciences.Väitekiri filosoofiadoktori kraadi taotlemiseks tehnikateaduse erialal.Global energy consumption and demand are increasing every year. In 2018, the distribution of global energy consumption was as follows: 51% heat production, 17% electricity production and 32% transportation sector. There are a number of sustainable “green” alternatives to fossil resources for heat and electricity production however, alternative solutions for the transportation sector are lacking. Presently, the biofuels used to reduce the share of fossil fuels are mostly produced from sugar, starch or oil-rich food crops. In order to avoid competition between food and fuels, the greatest potential is seen in the second-generation biofuels, such as bioethanol, which are produced using different plant (lignocellulosic) residues as a feedstock. It is possible to produce bioethanol, biodiesel and, for example, synthesis gas, but compared to the first generation, the production is much more complex due to characteristics of raw material therefore requiring a higher energy input. The second-generation bioethanol production chain includes several steps: pretreatment, hydrolysis, fermentation, and distillation. The most important process in the entire production chain is pretreatment. The more efficient the pretreatment, the higher the yield of sugars and ethanol that can be achieved. In order to increase the competitiveness of the second-generation bioethanol as an alternative motor fuel, various pretreatment methods were studied in the framework of this doctoral thesis to ensure maximum cellular structure disruption with minimal energy and no chemical input. Freezing, as a potential zero-energy pre-treatment method for the Nordic climate, and explosive decompression method were investigated in order to determine the optimal pretreatment process parameters.Energia tarbimine ja nõudlus suureneb maailmas iga-aastaselt. 2018. aastal oli ülemaailmse energia tarbimise jaotus järgnev: 51% soojusenergia, 17% elektrienergia ja 32% transpordisektor. Kui soojus- ja elektrienergia tootmiseks on olemas mitmeid jätkusuutlikke „rohelisi“ alternatiive asendamaks fossiilsete ressursside osakaalu, siis transpordisektori puhul need suurel määral puuduvad. Praegusel hetkel kasutatakse fossiilset päritolu mootorikütuste osakaalu vähendamiseks enamasti esimese põlvkonna biokütuseid, mis on toodetud suhkru-, tärklise- või õlirikastest toidukultuuridest. Vältimaks toiduainete ja mootorikütuste omavahelist konkurentsi nähakse enim potentsiaali teise põlvkonna biokütustes nagu näiteks bioetanool, mille tootmisel kasutatakse toormeks erinevaid taimseid (lignotselluloosseid) jääkmaterjale. Toota on võimalik nii bioetanooli, biodiislikütust kui ka näiteks sünteesgaasi, kuid võrreldes esimese põlvkonnaga on tootmine toorme iseärasustest tingituna märksa keerukam ning vajab suuremat energeetilist sisendit. Lignotselluloossest biomassist bioetanooli tootmine nõuab toorme eeltöötlemist, hüdrolüüsimist, kääritamist ning destilleerimist. Kõige olulisem protsess kogu bioetanooli tootmisahelas on eeltöötlus. Mida efektiivsem on eeltöötlus, seda kõrgemaid suhkrute ja etanooli saagiseid on võimalik saavutada. Saavutamaks kõrgeimaid võimalikke saagiseid uuriti antud doktoritöö raames erinevaid eeltöötlusmeetodeid, tagamaks maksimaalne rakustruktuuri lõhkumine kemikaalivabalt ning minimaalse energeetilise sisendiga eesmärgiga suurendada teise põlvkonna bioetanooli kui alternatiivse mootorikütuse, konkurentsivõimet. Uuriti nii külmutamiste, kui potentsiaale nullenergeetilise sisendiga eeltöötlusmeetodit põhjamaisesse kliimasse, kui ka plahvatusliku rõhulangetuse meetodit, selgitamaks välja optimaalseimad eeltöötlusprotsessi parameetrid.Publication of this dissertation is supported by the Estonian University of Life Sciences. This study has been supported by Estonian University of Life Sciences, Institute of Technology, Doctoral School of Energy and Geotechnology III (Estonian University of Life Sciences ASTRA project “Value-chain based bio-economy), European Union Regional Development Fund via the Estonians Research Council´s Mobilitas Pluss (Projects MOBERA1 and MOBERA2), and base financed EULS P170025 TIBT and PM180107TIBT projects. Also Doctoral Studies and Internationalisation Programme DoRa, Dora Plus programme “The Smart Specialisation scholarship for PhD students which were carried out by Foundation Archimedes

EXPLORATION OF THE POSSIBILITIES FOR THE PRODUCTION OF TABLEWARE FROM THE BRAN OF VARIOUS CEREALS

Biodegradable and compostable tableware is significantly more environment and nature friendly than disposable tableware and drinkware made of plastic. Tableware made of wheat bran, but also corn and rice bran is already commercially available. It is reasonable to use the by-products of the milling of also other cereals, like rye bran, barley bran and oat bran, for the production of tableware. The aim of this research was to explore the possibilities for the production of tableware and drinkware from the by-products of the milling of wheat and also other cereals like rye and oat bran. In order to achieve the aim, compacts were moulded from rye bran and oat bran and mixtures of bran (wheat bran and rye bran) using various work modes. The moulding of the compacts included different temperatures of the mould, moulding durations and compressive forces. The mechanical properties like density and flexural strength of the compacts were determined and the compostability of the compacts was studied. The test bodies were placed inside a compost bin to check their compostability and to determine the duration of composting.Biodegradable and compostable tableware is significantly more environment and nature friendly than disposable tableware and drinkware made of plastic. Tableware made of wheat bran, but also corn and rice bran is already commercially available. It is reasonable to use the by-products of the milling of also other cereals, like rye bran, barley bran and oat bran, for the production of tableware. The aim of this research was to explore the possibilities for the production of tableware and drinkware from the by-products of the milling of wheat and also other cereals like rye and oat bran. In order to achieve the aim, compacts were moulded from rye bran and oat bran and mixtures of bran (wheat bran and rye bran) using various work modes. The moulding of the compacts included different temperatures of the mould, moulding durations and compressive forces. The mechanical properties like density and flexural strength of the compacts were determined and the compostability of the compacts was studied. The test bodies were placed inside a compost bin to check their compostability and to determine the duration of composting

Comparison of different chemical-free pretreatment methods for the production of sugars, ethanol and methane from lignocellulosic biomass

Received: February 19th, 2023 ; Accepted: June 3rd, 2023 ; Published: July 3rd, 2023 ; Correspondence: [email protected], [email protected] pretreatment methods for lignocellulosic biomass use strong chemicals, such as sulphuric acid and ammonia, to open up the cellular structure of plant biomass. However, those chemicals are not environmentally friendly and their use leads to safety risks. As a result, different chemical-free pretreatment methods have been developed, which focus on the usage of pressure, high or low temperatures and mild chemicals. Freezing pretreatment and explosive decompression pretreatments, using different operating gases, such as nitrogen and steam, are compared in the context of glucose, ethanol and methane yield in this review. For the methane production, the stillage from bioethanol production is used. The usage of this waste improves the overall valorisation of lignocellulosic biomass. The review also investigates, whether the nitrogen explosive decompression pretreatment is suitable for the treatment of softwoods, hardwoods and herbaceous materials. In the comparison of different chemical-free pretreatment methods, it is concluded that heat and water are the most influential parameters for opening up the lignocellulosic biomass structure. The operating gas and pressure in the pretreatment reactor are less relevant. Steam explosion, nitrogen explosive decompression pretreatment and autohydrolysis pretreatment are the most suitable chemical-free pretreatment methods for lignocellulosic biomass

Degradation of lignocellulosic raw material using explosive decompression

Töö eesmärgiks oli uurida lämmastikplahvatuse eeltöötlusmeetodi sobivust linnahaljastuses tekkivate jäätmete töötlemiseks sihiga toota bioetanooli ning analüüsida praktilistele katsetustele toetudes hetkel kütustelaboris kasutatava seadmestiku puudusi, mille põhjal pakkuda välja tehniline lahendus nende puuduste likvideerimiseks ja eeltöötluse efektiivsemaks muutmiseks. Praktiliste katsetuste eesmärgiks oli määrata seadmele esitatavad minimaalsed nõudmised temperatuuri ja rõhu suhtes, millele toetuvad antud töös teostatud arvutused. Hetkel kasutusel oleval seadmestikul esineb mitmeid puudusi, mille likvideerimine muudaks protsessi oluliselt efektiivsemaks: 1. Seadmestik töötab tsükliliselt, mis tingib suure ajakulu. Korraga töödeldava biomassi hulk on väike. 100 g kuiva biomassi töötlemiseks ehk ühe katse teostamiseks kulunud aeg 125°C-ga oli keskmiselt 2,5 tundi ja 175°C-ga 3,5 tundi. 2. Reaktoris puudub segisti ja küttekeha on otseses kontaktis reaktori seinaga, mistõttu osa biomassi söestub reaktori seintele. 3. Jääksoojuse kasutamist ei toimu. Magistritöö tulemusena väljapakutud seadmestiku eelised hetkel kasutusel oleva seadmestiku ees: 1. Ajakulu vähendamiseks ja seadme tootlikkuse tõstmiseks on uus tehniline lahendus pidevprotsessiline ja võimaldab töödelda antud juhul 1000L biomassi segu ööpäevas (100 kg kuiva lignotsellulooset biomassi). 2. Välja pakutud lahendus on varustatud segistiga, mis ei lase biomassil ladestuda mahuti seintele. Segamisega tagatakse ka parem kontakt süsteemis kasutatava lämmastikuga. Biomassi soojendamine algab eelsoojendamisega mahutites ja jätkub spiraalses torureaktoris kuuma õli vahendusel. 3. Välja pakutud lahenduse puhul kasutatakse eeltöötluse läbinud biomassi jahtumisel eralduvat jääksoojust biomassi eelsoojendamiseks.The aim of this master’s thesis was to analyse the advantages and disadvantages of different equipment for the pre-treatment of lignocellulosic biomass, used to produce bioethanol, and to provide a technical solution for a continuous nitrogen explosion pre-treatment apparatus. Practical experiments were carried out using two different lignocellulosic urban waste: autumn maple leaves (V. Leht) and a mixture of leaves, grass and twigs (HJ). The aims of these experiments were to determine the effectiveness of the nitrogen explosion pre-treatment method and to determine the drawbacks of the apparatus used in fuel laboratory at present. The objective was to provide a pre-treatment apparatus which would work in continuous process and would not have the faults that the apparatus currently in use has

Briquetting Technologies and Standards for Solid Biofuels

Töös on käsitletud erinevaid tehnoloogiaid muundamaks tootmises tekkivaid jäätmeid kasutuskõlbulikuks kütuseks tavatarbijatele. Töö käigus sooritatud katsete järgi on arvutatud MWh-i soojusenergia maksumus. Esitatud on ka tahkete biokütuste standardid, mida peavad järgima kõik Euroopa Liidu liikmesriikide ja kandidaatriikide standardiseerimisametid. Vastavalt standardites EVS-EN15210-2:2010 ja EVS-EN 15103:2010 esitatud tingimustele on valminud ka mehaanilise vastupidavuse katsestendi ja puistetiheduse määramise konteineri eskiisjoonised. Praegusel hetkel on müügil brikette, mis on toodetud nii põhust kui ka saepurust, kuid nendest saadava soojusenergia MWh-i maksumus on vastavalt 29,5 % ja 35,8 % kallim kui tavalisel halupuidul. Suurest hinna erinevusest tingituna eelistatakse siiski kütteks kasutada halupuitu või turbast toodetud briketti, mis on peaaegu sama hinnaga. Katsetes kasutatud materjalidest pressitud briketid sobivad tavatarbijale kasutamiseks nii pliidi kui ka ahju kütmiseks. Ainukese materjalina ei sobi tavatarbijale koduseks kasutamiseks rehvi pürolüüsi jääde, kuna see oli väga määrivate omadustega. Briketid ja pelletid võimaldavad kasutada automatiseeritud küttesüsteeme erinevalt halupuidust ja kivisöest. Viimaste puhul pole automatiseerimine eratarbija puhul suuresti võimalik. Läbi viidud briketeerimis katsetest selgus, et tavatarbija jaoks oleks majanduslikult parimaks lahenduseks kasutada küttematerjalina siiski kivisütt või halupuitu, kuna nende puhul tuleks ühe MWh soojusenergia maksumus tavatarbijale madalaim. Samas oleks briketeerimine erinevate tööstusjääkide kütuseks väärindamisel küllalt perspektiivikas, mistõttu tasuks edasistes uuringutes kindlasti keskenduda ka briketeerimisele, kui ühele tööstusjääkide utiliseerimise võimalusele.The purpose of this research paper is to analyse advantages and disadvantages of different briquetting technologies. The research also gives an overview of the standards for solid biofuels used in Estonia and describes the methods for determining briquettes’ parameters, such as ash content, total moisture, bulk density, mechanical durability and calorific value according to these standards. The research paper also introduces pretreatment processes before briquetting. Depending on the material used for briquetting, different pretreatment processes are used to produdce homogenous and high-quality briquettes. Different production residues were used during the experiments. The experimental briquettes were analyzed as potential alternative fuel to fossil fuels

The Efficiency of Nitrogen and Flue Gas as Operating Gases in Explosive Decompression Pretreatment

As the pretreatment process is the most expensive and energy-consuming step in the overall second generation bioethanol production process, it is vital that it is studied and optimized in order to be able to develop the most efficient production process. The aim of this paper was to investigate chemical and physical changes in biomass during the process of applying the explosive decompression pretreatment method using two different gases—N2 and synthetic flue gas. The explosive decompression method is economically and environmentally attractive since no chemicals are used—rather it is pressure that is applied—and water is used to break down the biomass structure. Both pre-treatment methods were used at different temperatures. To be able to compare the effects of the pretreatment, samples from different process steps were gathered together and analysed. The results were used to assess the efficiency of the pretreatment, the chemical and physical changes in the biomass and, finally, the mass balances were compiled for the process during the different process steps of bioethanol production. The results showed that both pre-treatment methods are effective in hemicellulose dissolution, while the cellulose content decreases to a smaller degree. The high glucose and ethanol yields were gained with both explosive pretreatment methods at 175 °C (15.2–16.0 g glucose and 5.6–9.0 g ethanol per 100 g of dry biomass, respectively)

Biomass Pretreatment with the Szego Mill™ for Bioethanol and Biogas Production

Results from an investigation of the mechanical size reduction with the Szego Mill™ as a pretreatment method for lignocellulosic biomass are presented. Pretreatment is a highly expensive and energy-consuming step in lignocellulosic biomass processing. Therefore, it is vital to study and optimize different pretreatment methods to find a most efficient production process. The biomass was milled with the Szego Mill™ using three different approaches: dry milling, wet milling and for the first time nitrogen assisted wet milling was tested. Bioethanol and biogas production were studied, but also fibre analysis and SEM (scanning electron microscope) analysis were carried out to characterize the effect of different milling approaches. In addition, two different process flows were used to evaluate the efficiency of downstream processing steps. The results show that pretreatment of barely straw with the Szego Mill™ enabled obtaining glucose concentrations of up to 7 g L−1 in the hydrolysis mixture, which yields at hydrolysis efficiency of 18%. The final ethanol concentrations from 3.4 to 6.7 g L−1 were obtained. The lowest glucose and ethanol concentrations were measured when the biomass was dry milled, the highest when nitrogen assisted wet milling was used. Milling also resulted in an 6–11% of increase in methane production rate during anaerobic digestion of straw