Thermochemical gasification of local lignocellulosic biomass via fixed-bed and fluidized-bed reactors

DoktorgradsavhandlingThe government in Norway aims to double the bioenergy use from 14 TWh to 28 TWh between the year 2008 and 2020. This calls for major changes in the current energy practice and an increase in the biomass based energy applications in the total energy mix. One effort to this end is the replacement of existing space heating oil burners with heat from biomass combustion. However, this strategy alone could not be able to adequately meet the target of further bioenergy expansion. Neither will it help in achieving the Kyoto aim of reducing CO2 emission. So an alternative such as gasification could be a part of the solution. Gasification offers many advantages, but a major concern towards this technology is the logistics. A highly efficient gasification process would mean very little to a technical viability if efficient biomass supply is not guaranteed. Thus maintaining a smooth biomass supply to the conversion plant is important in perspective of which local lignocellulosic biomass could be an interesting option. In terms of the availability of lignocellulosic biomass, Norway is strategically well placed due thanks to its abundant forest reserves. Norway and forest are the two sides of the same coin which makes this country ever attractive in developing and practicing local bioenergy research, which is partly why this study is conducted. The main objective of the present project was to utilize local forest crops birch, oak and spruce and energy crops like poplar and willow as feedstocks for labscale fixed bed downdraft gasification. Further to evaluate the gasification performance interaction with biomass characteristics and process parameters, experimental work consisted of series of gasification tests was optimized over a range of air equivalence ratio (ER) between 0.19 and 0.45. The key results in terms of gas lower heating value (LHV), gas yield, cold gas efficiency (CGE) and carbon conversion efficiency (CCE) indicated that the producer gas obtained from all types of woodchips species gasification exhibited a great potential to be utilized for further downstream applications. Besides wood, in many places of the world the lion’s share of the biomass is contributed from herbaceous biomass. Hence this research also focused on two local herbaceous biomasses, alfalfa and wheat straw (in pellets) from Spain and one local herbaceous biomass common reed (in briquettes) from Norway for investigating gasification via two fluidized bed configurations being pilot-scale and lab-scale, and one fixed-bed downdraft gasifier respectively. Pilot-scale 4.7 kg/h air-blown gasification of sole alfalfa pellets was carried out at a variable ER between 0.25 and 0.30. The resulting bed temperature was ca 780 C and the maximum producer gas lower heating value (LHV) was ca 4.2 MJ/Nm3 which suits for combined heat and power application. Pilot-scale test also yielded producer gas composition rich in H2 composition (around 13 % dry basis vol.), indicating the potential of this gas to be utilized for hydrogen production. In addition to the pilot-scale tests, a series of lab-scale fluidized bed gasification on alfalfa and wheat straw pellets were conducted for a wide range of ER (0.20- 0.35) achieved by varying both fuel and air input. The optimized gasification performance attained for the two feedstocks differed in respect to the operational ER with a higher ER (0.35) for alfalfa and a lower ER (0.30) for wheat straw respectively. At the optimum condition, the gas produced from both the feedstocks exhibited a good LHV value above 4.1 MJ/Nm3 which can be recommended for engine or, turbine application. However, owing to the poor H2 composition of 4 %, this technology may not suit downstream H2 production. The fixed bed gasification on common reed briquettes on the other hand is a very recent addition to the current project which is not fully developed yet. Therefore the preliminary results obtained from a solitary test run were not representative. The measured parameters so far indicated that the gas LHV, bed temperature and ER range of 2.9 MJ/Nm3, 498 C and 0.35-0.86 respectively can be achieved. Last but not the least, a techno-economic modeling considering a producer gas generator in a 100 % renewable energy hybrid plant was performed for a standalone household in Grimstad by using HOMER (a commercial hybrid energy optimization tool). The results showed that producer gas generator together with the other renewable energy options is capable of fulfilling the annual electricity demand of a remote household with a constraint of a producer gas price less than 0.1$/Nm3. This system also provided environmental gain worth ~22,000 kg/year of CO2 equivalent savings. All in all, the influence of diverse local biomass feedstock on diverse gasification techniques is proved to be feasible in aspects of technology, economy and sustainability

Magnetic moments of A=3A = 3 nuclei with chiral effective field theory operators

Chiral effective field theory ($\chi$EFT) provides a framework for obtaining internucleon interactions in a systematically improvable fashion from first principles, while also providing for the derivation of consistent electroweak current operators. In this work, we apply consistently derived interactions and currents towards calculating the magnetic dipole moments of the $A=3$ systems Triton and Helium-3. We focus here on LENPIC interactions obtained using semilocal coordinate-space (SCS) regularization. Starting from the momentum-space representation of the LENPIC $\chi$EFT vector current, we derive the SCS-regularized magnetic dipole operator up through N2LO. We then carry out no-core shell model calculations for Triton and Helium-3 systems, using the SCS LENPIC interaction at N2LO in $\chi$EFT, and evaluate the magnetic dipole moments obtained using the consistently derived one-nucleon and two-nucleon electromagnetic currents. As anticipated by prior results with $\chi$EFT currents, the current corrections through N2LO provide improved, but not yet complete, agreement with experiment for the Triton and Helium-3 magnetic dipole moments.Comment: 30 pages, 2 figure

Calculations of p(n,γ)dp(n,\gamma )d reaction in chiral effective field theory

We present a calculation of the radiative capture cross section $p(n,\gamma )d$ in the low-energy range, where the $M1$ reaction channel dominates. Employing the LENPIC nucleon-nucleon interaction up to the fifth order (N4LO) that is regularized by the semi-local coordinate space regulators, we obtain the initial and final state wave functions, and evaluate the phase shifts of the scattering state and deuteron properties. We derive the transition operator from the chiral effective field theory up to the next-to-next-to leading order (N2LO), where we also regularize the transition operator using regulators consistent with those of the interactions. We compute the capture cross sections and the results show a converging pattern with the chiral-order expansion of the nucleon-nucleon interaction, where the regulator dependence of the results is weak when higher-order nucleon-nucleon interactions are employed. We quantify the uncertainties of the cross-section results due to the chiral-order truncation. The chirally complete and consistent cross-section results are performed up to N2LO and they compare well with the experiments and other theoretical predictions.Comment: 13 pages, 3 tables, 1 figur

Ab Initio No Core Shell Model with Leadership-Class Supercomputers

Nuclear structure and reaction theory is undergoing a major renaissance with advances in many-body methods, strong interactions with greatly improved links to Quantum Chromodynamics (QCD), the advent of high performance computing, and improved computational algorithms. Predictive power, with well-quantified uncertainty, is emerging from non-perturbative approaches along with the potential for guiding experiments to new discoveries. We present an overview of some of our recent developments and discuss challenges that lie ahead. Our foci include: (1) strong interactions derived from chiral effective field theory; (2) advances in solving the large sparse matrix eigenvalue problem on leadership-class supercomputers; (3) selected observables in light nuclei with the JISP16 interaction; (4) effective electroweak operators consistent with the Hamiltonian; and, (5) discussion of A=48 system as an opportunity for the no-core approach with the reintroduction of the core.Comment: 23 pages, 7 figures, Conference Proceedings online at http://ntse.khb.ru/files/uploads/2016/proceedings/Vary.pd

Thermochemical gasification of local lignocellulosic biomass via fixed-bed and fluidized-bed reactors

The government in Norway aims to double the bioenergy use from 14 TWh to 28 TWh between the year 2008 and 2020. This calls for major changes in the current energy practice and an increase in the biomass based energy applications in the total energy mix. One effort to this end is the replacement of existing space heating oil burners with heat from biomass combustion. However, this strategy alone could not be able to adequately meet the target of further bioenergy expansion. Neither will it help in achieving the Kyoto aim of reducing CO2 emission. So an alternative such as gasification could be a part of the solution. Gasification offers many advantages, but a major concern towards this technology is the logistics. A highly efficient gasification process would mean very little to a technical viability if efficient biomass supply is not guaranteed. Thus maintaining a smooth biomass supply to the conversion plant is important in perspective of which local lignocellulosic biomass could be an interesting option. In terms of the availability of lignocellulosic biomass, Norway is strategically well placed due thanks to its abundant forest reserves. Norway and forest are the two sides of the same coin which makes this country ever attractive in developing and practicing local bioenergy research, which is partly why this study is conducted. The main objective of the present project was to utilize local forest crops birch, oak and spruce and energy crops like poplar and willow as feedstocks for labscale fixed bed downdraft gasification. Further to evaluate the gasification performance interaction with biomass characteristics and process parameters, experimental work consisted of series of gasification tests was optimized over a range of air equivalence ratio (ER) between 0.19 and 0.45. The key results in terms of gas lower heating value (LHV), gas yield, cold gas efficiency (CGE) and carbon conversion efficiency (CCE) indicated that the producer gas obtained from all types of woodchips species gasification exhibited a great potential to be utilized for further downstream applications. Besides wood, in many places of the world the lion’s share of the biomass is contributed from herbaceous biomass. Hence this research also focused on two local herbaceous biomasses, alfalfa and wheat straw (in pellets) from Spain and one local herbaceous biomass common reed (in briquettes) from Norway for investigating gasification via two fluidized bed configurations being pilot-scale and lab-scale, and one fixed-bed downdraft gasifier respectively. Pilot-scale 4.7 kg/h air-blown gasification of sole alfalfa pellets was carried out at a variable ER between 0.25 and 0.30. The resulting bed temperature was ca 780 C and the maximum producer gas lower heating value (LHV) was ca 4.2 MJ/Nm3 which suits for combined heat and power application. Pilot-scale test also yielded producer gas composition rich in H2 composition (around 13 % dry basis vol.), indicating the potential of this gas to be utilized for hydrogen production. In addition to the pilot-scale tests, a series of lab-scale fluidized bed gasification on alfalfa and wheat straw pellets were conducted for a wide range of ER (0.20- 0.35) achieved by varying both fuel and air input. The optimized gasification performance attained for the two feedstocks differed in respect to the operational ER with a higher ER (0.35) for alfalfa and a lower ER (0.30) for wheat straw respectively. At the optimum condition, the gas produced from both the feedstocks exhibited a good LHV value above 4.1 MJ/Nm3 which can be recommended for engine or, turbine application. However, owing to the poor H2 composition of 4 %, this technology may not suit downstream H2 production. The fixed bed gasification on common reed briquettes on the other hand is a very recent addition to the current project which is not fully developed yet. Therefore the preliminary results obtained from a solitary test run were not representative. The measured parameters so far indicated that the gas LHV, bed temperature and ER range of 2.9 MJ/Nm3, 498 C and 0.35-0.86 respectively can be achieved. Last but not the least, a techno-economic modeling considering a producer gas generator in a 100 % renewable energy hybrid plant was performed for a standalone household in Grimstad by using HOMER (a commercial hybrid energy optimization tool). The results showed that producer gas generator together with the other renewable energy options is capable of fulfilling the annual electricity demand of a remote household with a constraint of a producer gas price less than 0.1$/Nm3. This system also provided environmental gain worth ~22,000 kg/year of CO2 equivalent savings. All in all, the influence of diverse local biomass feedstock on diverse gasification techniques is proved to be feasible in aspects of technology, economy and sustainability

Exploring biogas potential data of cattle manure and olive cake to gain insight into farm and commercial scale production

This article presents raw data of volumetric biogas and its methane composition obtained from anaerobic digestion experiments conducted under lab scale condition. A commercial biogas industry in Trondheim (Norway) developed interest in using olive cake from a Danish farm (Combineering A/S, Birkerød, Denmark) as a substrate for its existing biogas plant. Moreover, local cattle farm owners wanted to evaluate the possibility of investing on a biogas plant using cattle manure generated on their own farmlands. Accordingly, an evaluation of biogas production potential of these substrates was performed and the obtained data in brief are presented

By-products of fish-oil refinery as potential substrates for biogas production in Norway: a preliminary study

Norway is one of the biggest fish exporters in the world, and the fish industry is the second biggest economy of the country after oil and natural gas. As fish industries expand rapidly, the resulting fish-oil refining by-products are also receiving an upsurge interest, giving an enormous window of opportunity in generating bioenergy through this route. A number of fish-oil refinery by-products such as soapstock, glycerol, ethyl monoesters (light and dark) were utilized in the present study where the anaerobic digestion feasibility of these by-products as co-substrates with fish ensilage (acidified fish waste) was investigated. The method utilized was biomethane potential experiment by employing a series of 0.5 ​L batch bottles as anaerobic digesters operated at total feeding of about 7.0 ​g with co-substrates feeding ranging between 0.6 and 2.0 ​g per bottle. The digestion environment was set at extreme mesophilic having temperature of 39 ​± ​1 ​°C. During the ~65 days of experiment, it was found that accumulated volumetric biogas yield (in mL) from co-digestion of monoesters and fish ensilage was much higher than that of the mono digester operated with fish ensilage alone. The accumulated yield from light and dark monoesters co-digesters amounted to ~2100 ​mL and ~1950 ​mL respectively. In terms of specific biogas yield, highest yield was obtained from the soapstock co-digesters with an average peaking to 775 mL/gTS. The average methane content in biogas for all the digesters over the course of the experiment was found as ca 61%. The study concludes that fish-oil refinery by-products as co-substrates with fish ensilage upon utilization to anaerobic digestion plants can potentially offer Norwegian fish refineries an excellent opportunity to contribute heavily in local bioeconomy

Exploring biogas potential data of cattle manure and olive cake to gain insight into farm and commercial scale production

This article presents raw data of volumetric biogas and its methane composition obtained from anaerobic digestion experiments conducted under lab scale condition. A commercial biogas industry in Trondheim (Norway) developed interest in using olive cake from a Danish farm (Combineering A/S, Birkerød, Denmark) as a substrate for its existing biogas plant. Moreover, local cattle farm owners wanted to evaluate the possibility of investing on a biogas plant using cattle manure generated on their own farmlands. Accordingly, an evaluation of biogas production potential of these substrates was performed and the obtained data in brief are presented