| 1. |
- Abubaker, Jamal, et al.
(författare)
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Biogas residues as fertilisers - Effects on wheat growth and soil microbial activities
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 99, s. 126-134
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Tidskriftsartikel (refereegranskat)abstract
- Residues from the biogas process are a relatively new type of organic fertiliser with composition varying with origin of the raw material fed into the biogas process. The performance of four different biogas residues (BRs) was evaluated and compared with that of pig slurry (PS) and mineral fertiliser (NPK) in pots filled with sandy soil and fertilised at rates corresponding to 35,70 and 140 kg NH4+-N ha(-1). After sowing with spring wheat, the pots were incubated in a growth chamber. Total biomass yield and relative yields of ear, straw and root fractions were measured at harvest. Nitrogen mineralisation capacity (NMC) and potential ammonium oxidation rate (PAO) in soil were assessed. The fertilisation based on NH4+-N led to high addition of Tot C, Org N, Tot P, Tot K, Tot Mg and Zn at application of PS compared with BR. Biomass yields generally increased with increasing fertiliser rate but the response varied between the fertilisers. The BR yields compared well with NPK, but PS resulted in significantly higher yields. PS gave lower relative biomass of ears and higher relative biomass of roots compared with BR and NPK. The BR treatment yielding the lowest overall biomass also produced plants with the lowest relative root biomass, but partly compensated for this by increasing the relative ear biomass with increasing fertiliser rate. The NMC and PAO in soil had increased by the end of the experiment in almost all treatments. The high NMC in the PS treatment resulted in calculated mineralised N corresponding to 50-82 kg ha(-1) during the experimental period. In conclusion, fertilisation with biogas residues gave similar biomass yields but increased NMC and PAO in soil compared with NPK. Pig slurry gave the overall highest yields and NMC, but a PAO comparable to most BR. (C) 2012 Elsevier Ltd. All rights reserved.
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| 2. |
- Acuña, José, 1982-, et al.
(författare)
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Distributed thermal response tests on pipe-in-pipe borehole heat exchangers
- 2013
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 109:SI, s. 312-320
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Tidskriftsartikel (refereegranskat)abstract
- Borehole Thermal Energy Storage systems typically use U-pipe Borehole Heat Exchangers (BHE) having borehole thermal resistances of at least 0.06 K m/W. Obviously, there is room for improvement in the U-pipe design to decrease these values. Additionally, there is a need for methods of getting more detailed knowledge about the performance of BHEs. Performing Distributed Thermal Response Tests (DTRT) on new proposed designs helps to fill this gap, as the ground thermal conductivity and thermal resistances in a BHE can be determined at many instances in the borehole thanks to distributed temperature measurements along the depth. In this paper, results from three heat injection DTRTs carried out on two coaxial pipe-in-pipe BHEs at different flow rates are presented for the first time. The tested pipe-in-pipe geometry consists of a central tube inserted into a larger external flexible pipe, forming an annular space between them. The external pipe is pressed to the borehole wall by applying a slight overpressure at the inside, resulting in good thermal contact and at the same time opening up for a novel method for measuring the borehole wall temperature in situ, by squeezing a fiber optic cable between the external pipe and the borehole wall. A reflection about how to calculate borehole thermal resistance in pipe-in-pipe BHEs is presented. Detailed fluid and borehole wall temperatures along the depth during the whole duration of the DTRTs allowed to calculate local and effective borehole thermal resistances and ground thermal conductivities. Local thermal resistances were found to be almost negligible as compared to U-pipe BHEs, and the effective borehole resistance equal to about 0.03 K m/W. The injected power was found to be almost evenly distributed along the depth.
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| 3. |
- Akhtar, Farid, et al.
(författare)
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Colloidal processing and CO2 capture performance of sacrificially templated zeolite monoliths
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 97, s. 289-296
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Sacrificial templating of suspension cast and subsequently thermally treated zeolite monoliths with glassy carbon spheres and fibers yielded zeolite 13X and silicalite-1 monoliths with macroporosities up to 50 vol%. Homogeneous distribution of the macroporosity in hierarchically porous monoliths was obtained by tailoring the surface chemistry of the carbon particles by polyelectrolyte-assisted adsorption of zeolite particles. The effect of amount of kaolin binder and temperature for the thermal treatment on the monoliths strength, surface area and CO2 uptake was studied by diametral compression tests, electron microscopy, X-ray diffraction and gas adsorption. Cyclic adsorption and regeneration measurements showed that zeolite 13X monoliths display a high CO2 uptake while the silicalite-1 monoliths could be regenerated with a relatively low energy penalty.
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| 4. |
- Amiri, Shahnaz, et al.
(författare)
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Possibilities and consequences of deregulation of the European electricity market for connection of heat sparse areas to district heating systems
- 2010
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 87:7, s. 2401-2410
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the study is to analyse the conditions for connection of residential buildings in heat sparse areas to district heating systems in order to increase electricity production in municipal combined heat and power plants. The European electricity market has been assumed to be fully deregulated. The relation between connection of heat sparse areas, increased electricity and heat production as well as electricity prices, fuel prices and emissions rights is investigated. The results of the study show that there is potential to expand the district heating market to areas with lower heat concentrations in the cities of Gavle, Sandviken and Borlange in Sweden, with both economic and environmental benefits. The expansion provides a substantial heat demand of approximately 181 GWh/year, which results in an electricity power production of approximately 43 GWh/year. Since the detached and stand-alone houses in the studied heat sparse areas have been heated either by oil boiler or by direct electricity, connection to district heating also provides a substantial reduction in emissions of CO(2). The largest reductions in CO(2) emissions are found to be 211 ktonnes/year assuming coal-fired condensing power as marginal electricity production. Connection of heat sparse areas to district heating decrease the system costs and provide a profitability by approximately 22 million EURO/year for the studied municipalities if the price of electricity is at a European level, i.e. 110 EURO/MWh. Sensitivity analysis shows, among other things, that a strong relation exists between the price of electricity and the profitability of connecting heat sparse areas to district heating systems.
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| 5. |
- Andersson, Jan-Olof, et al.
(författare)
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Improved energy efficiency in juice production through waste heat recycling
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 130:S1, s. 757-763
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Tidskriftsartikel (refereegranskat)abstract
- Berry juice concentrate is produced by pressing berries and heating up the juice. The by-products are berry skins and seeds in a press cake. Traditionally, these by-products have been composted, but due to their valuable nutrients, it could be profitable to sell them instead. The skins and seeds need to be separated and dried to a moisture content of less than 10 %wt (on dry basis) in order to avoid fermentation. A berry juice plant in the north of Sweden has been studied in order to increase the energy and resource efficiency, with special focus on the drying system. This was done by means of process integration with mass and energy balance, theory from thermodynamics and psychrometry along with measurements of the juice plant. Our study indicates that the drying system could be operated at full capacity without any external heat supply using waste heat supplied from the juice plant. This would be achieved by increasing the efficiency of the dryer by recirculation of the drying air and by heat supply from the flue gases of the industrial boiler. The recirculation would decrease the need of heat in the dryer with about 52%. The total heat use for the plant could thereby be decreased from 1262 kW to 1145 kW. The improvements could be done without compromising the production quality.
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| 6. |
- Andersson, Jan-Olof, et al.
(författare)
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Improved energy efficiency in sawmill drying system
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 113, s. 891-901
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Tidskriftsartikel (refereegranskat)abstract
- The worldwide use of biomass has increased drastically during the last decade. At Swedish sawmills about half of the entering timber becomes lumber, with the remainder considered as by-product (biomass). A significant part of this biomass is used for internal heat production, mainly for forced drying of lumber in drying kilns. Large heat losses in kilns arise due to difficulties in recovering evaporative heat in moist air at low temperatures. This paper addresses the impact of available state-of-the-art technologies of heat recycling on the most common drying schemes used in Swedish sawmills. Simulations of different technologies were performed on an hourly basis to compare the heat and electricity demand with the different technologies. This was executed for a total sawmill and finally to the national level to assess the potential effects upon energy efficiency and biomass consumption. Since some techniques produce a surplus of heat the comparison has to include the whole sawmill. The impact on a national level shows the potential of the different investigated techniques. The results show that if air heat exchangers were introduced across all sawmills in Sweden, the heat demand would decrease by 0.3 TWh/year. The mechanical heat pump technology would decrease the heat demand by 5.6 TWh/year and would also produce a surplus for external heat sinks, though electricity demand would increase by 1 TWh/year. The open absorption system decreases the heat demand by 3.4 TWh/year on a national level, though at the same time there is a moderate increase in electricity demand of 0.05 TWh/year. Introducing actual energy prices in Sweden gives an annual profit (investment cost excluded) on national level for the open absorption system of almost 580 million SEK. For the mechanical heat pump technology the profit is 204 million SEK and for the traditional heat exchanger the profit is significant lower. It has been found that a widespread implementation of available energy recovery technologies across Swedish sawmills would result in substantial savings of biomass for other purposes in the society
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| 7. |
- Andersson, Jan-Olof, et al.
(författare)
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Improving energy efficiency of sawmill industrial sites by integration with pellet and CHP plants
- 2013
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 111, s. 791-800
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Tidskriftsartikel (refereegranskat)abstract
- An essential strategy to lower energy and resources consumption is the development of highly integrated industrial sites including different kind of plants complementing one another. Sawmills are huge biomass suppliers to other industries, such as pulp and paper mills, pellet plants and CHP plants, and part of the biomass is also used for the internal heat requirement. In this paper the integration of a sawmill with a pellet plant and a CHP plant is investigated using advanced process integration techniques, so that the thermal energy and the electricity produced in the CHP plant by burning part of the sawmill biomass output are used for the heat and power requirements of the other two industries. The results show that up to 18% of the biomass by-products from the sawmill can be saved, but from the economic point of view the ratio between prices of the thermal energy sold for district heating and the low quality biomass has to be lower than the present one to make the integrated design solution more attractive than separate plant operation.
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| 8. |
- Andersson, Jan-Olof, et al.
(författare)
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Surplus biomass through energy efficient kilns
- 2011
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 88:12, s. 4848-4853
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Tidskriftsartikel (refereegranskat)abstract
- The use of biomass in the European Union has increased since the middle of the 1990s, mostly because of high subsidies and CO2 emission regulation through the Kyoto protocol. The sawmills are huge biomass suppliers to the market; out of the Swedish annual lumber production of 16.4 Mm3, 95% is produced by medium to large-volume sawmills with a lumber quotient of 47%. The remaining part is produced as biomass. An essential part (12%) of the entering timber is used for supply of heat in their production processes, mostly in the substantial drying process. The drying process is the most time and heat consuming process in the sawmill. This study was undertaken to determine the sawmills’ national use of energy and potential magnitude of improvements. If the drying process can be made more effective, sawmills’ own use of biomass can be decreased and allow a considerably larger supply to the biomass market through processed or unprocessed biomass, heat or electricity production. The national electricity and heat usage when drying the lumber have been analysed by theoretical evaluation and experimental validation at a batch kiln. The main conclusion is that the heat consumption for drying lumber among the Swedish sawmills is 4.9 TW h/year, and with available state-of-the-art techniques it is possible to decrease the national heat consumption by approximately 2.9 TW h. This additional amount of energy corresponds to the market’s desire for larger energy supply.
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| 9. |
- Andersson, Jim, et al.
(författare)
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Techno-economic analysis of ammonia production via integrated biomass gasification
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 130:S1, s. 484-490
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Tidskriftsartikel (refereegranskat)abstract
- Ammonia (NH3) can be produced by synthesis of nitrogen and hydrogen in the Haber–Bosch process, where the economic challenge is the hydrogen production. Currently, substantial amounts of greenhouse gases are emitted from the ammonia industry since the hydrogen production is almost exclusively based on fossil feedstocks. Hydrogen produced via gasification of lignocellulosic biomass is a more environmentally friendly alternative, but the economic performance is critical. The main objective of this work was to perform a techno-economic evaluation of ammonia production via integrated biomass gasification in an existing pulp and paper mill. The results were compared with a stand-alone production case to find potential technical and economic benefits deriving from the integration. The biomass gasifier and the subsequent NH3 production were modelled using the commercial software Aspen Plus. A process integration model based on Mixed Integer Linear Programming (MILP) was used to analyze the effects on the overall energy system of the pulp mill. Important modelling constraints were to maintain the pulp production and the steam balance of the mill. The results showed that the process economics and energy performance are favourable for the integrated case compared to stand-alone production. The main conclusion was however that a rather high NH3 selling price is required to make both production cases economically feasible.
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| 10. |
- Andersson, Martin, et al.
(författare)
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Review on Modeling Development for Multiscale Chemical Reactions Coupled Transport Phenomena in Solid Oxide Fuel Cells
- 2010
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 87:5, s. 1461-1476
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Forskningsöversikt (refereegranskat)abstract
- A literature study is performed to compile the state-of-the-art, as well as future potential, in SOFC modeling. Principles behind various transport processes such as mass, heat, momentum and charge as well as for electrochemical and internal reforming reactions are described. A deeper investigation is made to find out potentials and challenges using a multiscale approach to model solid oxide fuel cells (SOFCs) and combine the accuracy at microscale with the calculation speed at macroscale to design SOFCs, based on a clear understanding of transport phenomena, chemical reactions and functional requirements. Suitable methods are studied to model SOFCs covering various length scales. Coupling methods between different approaches and length scales by multiscale models are outlined. Multiscale modeling increases the understanding for detailed transport phenomena, and can be used to make a correct decision on the specific design and control of operating conditions. It is expected that the development and production costs will be decreased and the energy efficiency be increased (reducing running cost) as the understanding of complex physical phenomena increases. It is concluded that the connection between numerical modeling and experiments is too rare and also that material parameters in most cases are valid only for standard materials and not for the actual SOFC component microstructures.
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