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Systemoptimerad produktion av fordonsgas En miljö- och energisystemanalys av Söderåsens biogasanläggning
... Anläggning 1 hade en rapporterad elförbrukning år 2019-2020 på 80 kWh/ton substrat (Uppsala Vatten, 2020). Det är ett högt värde i jämförelse med vad som rapporterats i tidigare biogasstudier (Berglund and Börjesson, 2006;Lantz et al., 2009). Det är dock lägre än de 106 kWh/ton substrat som rapporterats från en energikartläggning vid samma anläggning år 2011 (Andersson, 2011 (Lantz et al., 2009), respektive 80 kWh/ton substrat, baserat på den specifika förbrukningen vid anläggning 1 där huvuddelen av avfallet krävde mycket förbehandling. ...
... Det är ett högt värde i jämförelse med vad som rapporterats i tidigare biogasstudier (Berglund and Börjesson, 2006;Lantz et al., 2009). Det är dock lägre än de 106 kWh/ton substrat som rapporterats från en energikartläggning vid samma anläggning år 2011 (Andersson, 2011 (Lantz et al., 2009), respektive 80 kWh/ton substrat, baserat på den specifika förbrukningen vid anläggning 1 där huvuddelen av avfallet krävde mycket förbehandling. ...
... Eftersom emissionerna av växthusgaser från spridningen av biogödsel normalt är mycket lägre än från lagringen och från den spridda biogödseln beräknades emissionerna från spridningen enbart från den genomsnittliga energiförbrukningen vid spridning av biogödsel (Lantz et al., 2009;Lantz and Börjesson, 2014 Indirekta lustgasutsläpp beräknades med ekvation 7 och 8 vilka är baserade på ekvation 11.9 och 11.10 i IPCCs NGHGG (Buendia et al., 2019). Frac GASx är den fraktion av applicerat kväve som avgår till atmosfären som NH 3 och NO x . ...
Biofertilizers is generated as a co-product to biogas when digesting organic material in anaerobically in a biogas plant. In this study, the climate impact of biofertilizers and biogas systems were studied using life cycle assessment methodology. The study was loosely based on data from two real facilities co-digesting organic waste materials. The effects on soil carbon stocks were also assessed, when applying biofertilisers continuously on agricultural soils. This effect was based on results from respirometer trials performed in a laboratory setting, using digestates from the two biogas plants that
were modelled in the life cycle assessment.
In this report, a background to the biogas production and use of biofertiliser in Sweden today is given, as well as a detailed description of the life cycle assessment, including the soil experiments and calculations that formed the basis for the soil carbon modelling.
The results indicate that biofertilizers and biogas systems contribute to reducing greenhouse gas emissions from the Swedish food production system already today. The contribution to soil organic carbon stocks most likely makes well designed and controlled biogas systems close to carbon neutral. Systems with very low resource use and emission levels might even achieve a global cooling effect due to the potential soil carbon stock changes.
The exact climate impact from a biogas plant is however highly variable, and depends to a high degree on its ability to avoid leakage of methane, which is a highly potent greenhouse gas. Even small leakages can increase the impact from the system significantly. It is therefore important to be aware of the risk of leakage, both from the pant and the storage of the digestates. The later can cause very high emissions if the material leaving the biogas process has not been well digested.
The potential of biofertilisers and biogas systems co-digesting municipal waste contributing further to achieving a climate neutral food production system in Sweden by 2045 is however limited. Generated waste should definitely be processed to produce biogas and biofertilizers, which is being done to a large extent already today. Reducing the amount of waste should however be an overarching goal for society, since that increases resource use efficiency and minimizes environmental impacts, including climate impact. This inevitably reduces the amount of available feedstock for municipal waste biogas plants.
... The reactors are assumed to be ideally stirred, giving effluent concentrations equal to those in the reactor. The digestate is stored in covered storage tanks, with a loss of TAN amounting to 1% of N [20]. Storage capacity for crop digestate sufficient for 12-months´ production is included. ...
... In the literature, there are several reports of internal heat demand for biogas plants utilizing different kinds of feedstock. A demand in the range of 70-130 MJ/t has been reported [16,20,30,31,32], but there are also examples where the reported heat demand is as high as 250-330 MJ/Mg [16,33,34]. For comparison, a theoretically calculated heat demand for the feedstocks in the current study (assuming an average feedstock temperature of 8 °C, a process temperature of 37 °C and a specific heat capacity of water and dry matter of 4.18 and 1.0 kJ/kg/K respectively) would be 89-109 MJ/Mg. ...
... Electricity is used for feeding, stirring, pumping etc. and the demand is influenced by feedstock type and reactor design. In the literature, reported electricity input varies from 5-41 kWh/Mg [16,20,[31][32][33][34][35]. However, when the biogas is utilized for CHP, it is common that reported figures also include parasitic load for the production of CHP, which could represent 9-40% of the total electricity consumption [35]. ...
The vast majority of the biofuels presently used in the EU are so called first generation biofuels produced from crops. Concerns of food security, displacement of food crop production and indirect land use change (iLUC) has led to the introduction of measures to reduce the use of first generations biofuels and promote so called advanced biofuels based on feedstock that does not compete with food/feed crops, such as waste and agricultural residues. In Sweden, 60% of the biofuel consumption is already based on waste/residual feedstock, and a unique feature of the Swedish biofuel supply is the relatively large use of biogas for transport, representing 9% of the current use of biofuels. The use of waste/residues dominates the biogas production, but agricultural residues, representing a large domestic feedstock potential, are barely used at present. This could indicate that biofuels from such feedstock is non-competitive compared both to fossil fuels and to biofuels produced from crops and waste under existing policy framework. This study show that without subsidies, the production cost of biogas as biofuel from all non-food feedstocks investigated (grass, crop residues and manure) is higher than from food crops. A shift from food crops to residues, as desired according to EU directives, would thus require additional policy instruments favoring advanced biofuel feedstock. Investment or production subsidies must however be substantial in order for biogas from residues to be competitive with biogas from crops.
... Det antas också att samtliga anläggningar drivs under mesofila förhållanden och att materialet därför ska värmas upp till 37 o C. I litteraturen förekommer uppgifter om värmebehov från cirka 19 till 89 kWh per ton beroende på anläggningstyp och råvara (Berglund och Börjesson, 2006;Brown et al., 2011;FNR, 2006;FNR, 2010;Jury et al., 2010). Moderna svenska samrötningsanläggningar som i huvudsak rötar flytande biogasråvara uppger ett värmebehov på 24-34 kWh t -1 (Lantz et al., 2009;Lantz och Börjesson, 2014). ...
... Därutöver används också 0,11 kWh elektricitet per m 3 rågas för att uppgradera biogasen (Läckeby Water, 2012) och ytterligare 0,25 kWh per m 3 uppgraderad gas för att komprimera gasen från 0,4 till 20 MPa (Lantz et al., 2009). ...
I Skåne odlas 34 500 ha sockerbetor för sockerutvinning och i Sverige 36 000 ha
(Jordbruksstatistik årsbok 2014). Vid insamling och rötning av blasten från betorna i
Skåne skulle drygt 200 GWh biogas kunna produceras per år och driva minst 19 000 bilar
eller 1000 bussar. Men idag lämnas den i fält.
Tidigare studier har visat att betblast från sockerproduktion är på gränsen till lönsamt att
skörda och använda för biogasproduktion (Lantz, 2013b). I det här projektet har flera
forskare, en biogasproducent och en representant för betodlarna gemensamt tagit fram
och undersökt ett par förslag för hur skörd, lagring och rötning av betblast kan
genomföras och hur olika tillvägagångssätt påverkar kostnader och klimatpåverkan. Dessa
innefattar en jämförelse av två olika skördekedjor och undersökning av effekterna av att
fraktionera betblast före lagring och rötning på; biogasproduktion, ekonomi och
klimatpåverkan. För dessa beräkningar antogs att endast betblast rötades i en
biogasanläggning med en årlig produktion om 172 TJ (48 GWh) metan. Effekterna av att
introducera icke fraktionerad och fraktionerad betblast i en samrötningsanläggning
analyserades också. Dessutom arrangerades en skördedemonstration i oktober 2013 i
samarbete med Skånska Biobränslebolaget (länk till video). Analysen av skördeteknik har
begränsats till skörd av blast från betor odlade för sockerproduktion, vilket är det som
görs i Sverige idag. Om sockerbetor odlas endast för biogasproduktion kan andra
skördetekniker för betor och blast vara aktuella.
Studien har visat att när biogas från betblast ersatte fossil energi som drivmedel så sänktes
utsläppen av klimatgaser kraftigt, med 80 %. Därmed uppfylldes EUs hållbarhetskriterier
för biodrivmedel, både enligt dagens direktiv (35 % reduktion) och föreslagna framtida
(60 % reduktion). Viktigt i detta sammanhang är att blasten är en restprodukt och den
konkurrerar inte om åkermark för livsmedelsproduktion.
I Skåne skulle ca 200 GWh biogas kunna produceras från betblast vid dagens
sockerbetsproduktion. Men, även för den andel av blasten som skördas under september
(motsvarande ca 40 GWh), då det är mer gynnsamt än vid senare skörd, är det svårt att
hitta ekonomisk hållbarhet.
Studien tyder på att kostnader och klimatpåverkan är de samma om betblast fraktioneras
eller ej. I fallstudien framkom att fraktionering av betblasten gav praktisk möjlighet att ta
emot mer material i den studerade samrötningsanläggningen. Vätskefraktionen kunde då
ersätta vatten i förbehandlingen och mera torrsubstans (TS) kunde tas emot med den fasta
fraktionen innan uppehållstiden begränsade mängden i rötningsprocessen. Att ersätta
vatten i förbehandlingsanläggningen ger mindre kapitalkostnader per producerad MWh
jämfört med om man skulle röta denna fraktion i en dedikerad anläggning. Men, inte
heller i fallstudien medförde fraktionering lägre kostnader per producerad mängd metan.
Blastskörden visade sig vara högre i september, 3,6 ton torrsubstans per hektar (t TS/ha),
än i oktober, 3,2 t TS/ha, vilket gör det fördelaktigare att samla in blast i september än
oktober. Av de skörde- och transportkedjor som teoretiskt utvärderades i projektet var det
ekonomiskt mest fördelaktigt med en skördekedja där en mindre mängd blast samlades in
(55 % av tillgänglig mängd) för att minimera maskinernas väntetider. Alternativet har
dock nackdelen att en större andel kvarlämnad blast gör att en större andel av fältets yta får ojämn förfruktseffekt i efterföljande gröda jämfört med ett scenario då större andel av
blasten samlas in.
Priset för skörd (i september) och lagring beräknades till 1,7–2,1 kr/kg TS både med och
utan fraktionering. Detta är högre än det pris som tidigare beräknats (Gissén et al. 2014),
vilket bedöms som underskattat.
Tester av fraktionering av betblast gjordes i liten skala med en äppeljuicepress.
Metanpotentialtester gjordes på de olika fraktionerna. Pressning av strimlad blast (13 %
TS) gav en vätskefraktion (7 % TS) motsvarande en fjärdedel av våtvikten och 3 fjärdedelar
återstod som fast fraktion (15 % TS). Den fasta fraktionen gav dubbelt så högt
metanutbyte per kg våtvikt som vätskefraktionen, men ingen signifikant skillnad i
metanutbyte per kg organiskt material. Ingen inverkan av sortval på betblastskörden eller
metanutbyte per kg organiskt material kunde hittas vid test av fem sockerbetssorter som
förädlats fram för sockerproduktion.
När fraktionerad blast används kan möjlighet finnas att dubbelanvända lager för den våta
fraktionen och rötrest. Det gäller även för andra flytande substrat som behöver lagras.
Studien visar att dubbelanvändning kan påverka investeringskostnaderna för rötrestlagret
signifikant och en närmare undersökning av om det är praktiskt möjligt vore intressant.
När flera positiva faktorer samspelar kan det finnas möjlighet att med dagens
förhållanden producera biogas som biodrivmedel från betblast på ett ekonomiskt hållbart
sätt. Exempel på identifierade positiva faktorer är: högt blastutbyte, användning av
underutnyttjade jordbruksredskap, rötning i befintliga anläggningar för att fylla ut
substratluckor, korta transportsträckor och direktanvändning av färsk betblast utan
lagring. Det är troligtvis endast för en liten del av den totala mängden blast som tillräckligt
många positiva faktorer samspelar för att den idag ska kunna vara ekonomiskt intressant
att använda för biogasproduktion.
... [114]; b [115]; c [116]; d [117]; e [118]; f [119]; g [58]; h [57]; i [120]; j [121]; k [122]; l [123]; m [124]. Sources: a [125]; b [126]; c [127]; d [128]; e [32]; f [129]; g [130]. Electricity use was modelled using the dataset Electricity, low voltage {Europe without Switzerland}| market group for | APOS, S from Ecoinvent. ...
In the process of upgrading biogas to biomethane for gas grid injection or use as a vehicle fuel, biogenic carbon dioxide (CO₂) is separated and normally emitted to the atmosphere. Meanwhile, there are a number of ways of utilizing CO₂ to reduce the dependency on fossil carbon sources. This article assesses the climate performance of liquefied biomethane for road transport with different options for utilization or storage of CO₂. The analysis is done from a life cycle perspective, covering the required and avoided processes from biogas production to the end use of biomethane and CO₂. The results show that all of the studied options for CO₂ utilization can improve the climate performance of biomethane, in some cases contributing to negative CO₂ emissions. One of the best options, from a climate impact perspective, is to use the CO₂ internally to produce more methane, although continuous supply of hydrogen from renewable sources can be a challenge. Another option that stands out is concrete curing, where CO₂ can both replace conventional steam curing and be stored for a long time in mineral form. Storing CO₂ in geological formations can also lead to negative CO₂ emissions. However, with such long-term storage solutions, opportunities to recycle biogenic CO₂ are lost, together with the possibility of de-fossilizing processes that require carbon, such as chemical production and horticulture.
... Lantz et al. (2009) We have assumed large-scale modern plants which tend to have better performance. ...
Ensuring future food and energy security will require large changes in consumption and production patterns, including enhanced animal and human excreta recycling. Although these shifts are considered in many scenario studies, their implications on the logistical requirements for effective recycling are rarely analysed. Here we translated two existing stakeholder co-designed food system scenarios for Sweden to 5 × 5 km resolution maps of animals, crops, and humans. We used optimization modelling to identify biogas plant locations to minimize transport costs and maximize nutrient reuse. We then compared scenarios, including full recycling under current landscape configuration, through Life Cycle Assessment. The reduction in meat consumption and imported food in both co-designed scenarios, by definition, led to less nutrients available in manure for recycling back on cropland, and less material available for digestion. Less excreta meant lower national benefits, for example 50% less greenhouse gas emissions savings in the most divergent scenario. However on a per transport basis the benefits of recycling were more important: recycling remained a net financial benefit even if transport costs were to increase. Although fewer biogas plant locations were necessary (184 and 228 for alternative futures, vs 236 under current conditions) to process human and animal excreta, the regional clustering of locations did not change substantially across scenarios. Regions such as Skåne and Västra Götaland consistently required the most biogas plant locations across scenarios. Focusing early construction investments in these regions would be resilient to a large array of food system futures. Our spatially-explicit open access scenario maps can be used to explore logistics for such planning, and explore the impact of landscape configuration on other sustainability priority areas.
... Our model biogas production system receives 25000 of sorted and collected FW in biodegradable bags. Detailed information about the system and the assumptions can be found in the supplementary materials, mostly drawn from biogas literature [10,29,30,[36][37][38][39][40][41][42][43][44][45][46][46][47][48][49][50][51][52][53][54]. The anaerobic digestion is assumed to be a wet mesophilic system, including a hygienization step. ...
The anaerobic digestion of food waste can not only enhance the treatment of organic wastes, but also contributes to renewable energy production and the recirculation of nutrients. These multiple benefits are among the main reasons for the expansion of biogas production from food waste in many countries. We present methodological insights and recommendations on assessing the environmental and economic performance of these systems from a life-cycle perspective. We provide a taxonomy of the value chain of biogas from food waste which describes major activities, flows, and parameters across the value chain with a relatively high detail. By considering the multiple functions of biogas production from food waste, we propose a few key performance indicators (KPI) to allow comparison of different biogas production systems from the perspectives of climate impact, primary energy use, nutrients recycling, and cost. We demonstrate the operational use of our method through an example, where alternatives regarding the heat supply of the biogas plant are investigated. We demonstrate how global and local sensitivity analyses can be combined with the suggested taxonomy and KPIs for uncertainty management and additional analyses. The KPIs provide useful input into decision-making processes regarding the future development of biogas solutions from food waste.
... As presented earlier, the digestate is spread as a fertiliser on arable land. In this study, the increased amount of NH4-N and P that is spread compared to spreading of undigested manure is assumed to replace mineral fertilisers (Börjesson et al., 2009;Tufvesson et al. 2013). Thus, the biogas system benefits from avoided emissions from the production and spreading of mineral fertilisers. ...
The overall objective of this comparative systems study is to analyse and describe, from a well-to-wheel (WTW) perspective, the energy, greenhouse gas (GHG) and cost performance of existing and potential, new, methane-based vehicle systems solutions. Both thermal gasification (TG) sys-tems using forest residues, anaerobic digestion (AD) systems using organic waste and residues, and natural gas (NG) systems are included, as well as different upgrading technologies and distribution systems including compressed and liquefied methane, gas grids and containers transported by trucks etc. The end-use technologies included are light-duty and heavy-duty vehicles using spark-ignited (SI) otto engines and dual-fuel (DF) diesel engines. The reference systems consist of gaso-line-fuelled, light-duty vehicles and diesel-fuelled, heavy-duty vehicles. The GHG calculations are based on the methodology stated in the EU Renewable Energy Directive (RED), and the methodol-ogy recommended in the ISO standard of life cycle assessment.
The overall conclusion regarding the well-to-tank (WTT) GHG performance of the various renewa-ble methane supply systems, is that these vary only to a limited degree. Thus, the selection of sup-ply and distribution systems will have a minor impact on the WTW GHG performance. A similar conclusion can be drawn for the end-use technologies (tank-to-wheel, TTW), where the minor in-put of fossil diesel in DF trucks is partly compensated for by the higher energy conversion effi-ciency, compared with SI engine trucks. The WTW GHG reduction for the renewable methane sys-tems analysed, compared with the reference gasoline and diesel systems, amounts to roughly 80% or more when the RED calculation methodology is applied. The corresponding reductions for NG-based systems are approximately 10%.
Applying the ISO calculation methodology will give similar reduction levels, but a somewhat changed interrelation between the TG and AD supply systems. Critical aspects regarding the WTW GHG performance are methane losses throughout the fuel chain. One example is methane boil-off emissions from on-board storage tanks of liquefied methane, which may occur if the trucks are not in operation for several days. The relative amount of diesel in DF trucks will also affect the GHG performance, which will be affected by driving patterns and transport operations, as well as the fuel consumption efficiency for SI engine trucks using compressed NG.
The WTW primary energy input is somewhat higher in methane-fuelled vehicle systems than in comparable gasoline- and diesel-fuelled vehicle systems, vaying from +3% up to +33% depending on the type of methane-based powertrain system. The WTW primary energy input in the systems using compressed methane in trucks with SI engines is in the range of 10-15% higher than systems using liquefied methane in DF trucks. If liquefied methane is used as energy carrier in methane-fuelled SI engine trucks, instead of compressed methane, the corresponding total primary energy input increases slightly. A critical aspect regarding the WTW energy efficiency for methane-fuelled SI engine trucks is the fuel consumption, since this may vary due to driving patterns and transport operations. It is assumed that the fuel efficiency of DF trucks and diesel trucks is similar.
The WTT costs of biogas (produced by AD) and bio-methane (produced by TG) vehicle fuel sys-tems are estimated to be similar but these costs from smaller gasification systems are somewhat higher than the costs from the AD systems and larger TG systems. The costs of the different post-treatment and distribution systems of renewable methane are also comparable, and represent in the range of 20-40% of the total WTT costs. Thus, from an economic perspective, the selection of different production, post-treatment and distribution systems of renewable methane vehicle fuel systems are of minor importance. However, there are uncertainties in the WTT cost calculations per-formed, especially regarding the production costs of biogas and bio-methane.
The WTW costs of compressed methane-fuelled, light-duty vehicles are estimated to be in the range of 15-20% higher than the cost of gasoline-fuelled cars, independently of renewable me-thane or NG. The WTW costs include the current market price of the fossil-based fuels, excluding VAT but including other relevant taxes, and the additional vehicle cost of methane-fuelled cars and trucks (thus not the complete cost of the vehicle). For light-duty vehicles, the additional vehicle cost is estimated to represent some 25% of the WTW cost. The WTW costs are sensitive to changes in the market price of fossil-based fuels, including changes in taxes for both fossil and renewable vehicle fuels.
Liquid biogas- and bio-methane-fuelled DF trucks have WTW costs similar to corresponding diesel trucks, whereas liquid NG-fuelled DF trucks have slightly lower WTW costs. Compressed me-thane-fuelled trucks are estimated to have roughly 15-20% higher WTW costs than diesel trucks. The additional TTW costs of methane-fuelled trucks are estimated to represent some 10% of the WTW costs, but this may vary from 5 to 15%. It is estimated that the additional vehicle cost for DF trucks and SI trucks are similar. The uncertainties in the production costs of biogas and bio-me-thane will have a significant impact on the WTW costs. The highest and lowest WTT costs includ-ed in the uncertainty analysis lead to 30-50% higher, and 25% lower WTW costs, respectively, for the renewable methane-fuelled trucks, compared with diesel-fuelled trucks.
The overall conclusions of this study are that the use of renewable methane vehicle fuel systems leads to significant WTW GHG benefits, compared with fossil-based vehicle fuel systems, that the WTW energy efficiency will be comparable or slightly lower than comparable gasoline- and diesel-fuelled vehicles, and that the WTW costs will be comparable or slightly higher, based on current market prices of fossil fuels. The selection of post-treatment and distribution system of renewable methane vehicle fuel systems will be of minor importance regarding the WTW GHG, energy efficiency and cost performance. Thus, there is an incentive to develop and commercially implement all of the various renewable methane systems assessed in this study.
A circular biobased economy must be able to sustainably manage multiple resources simultaneously. Nutrient (nitrogen, phosphorus, and potassium) recycling and renewable energy production (biogas) can be compatible practices but require substantial transport of heavy organic waste. We combine a spatial optimization model and Life Cycle Assessment (LCA) to explore how Sweden could maximize its use of excreta resources. We use 10×10 km2 resolution data on the location of animal and human excreta and crop demand and model both optimal biogas plant locations and transport of nutrients to and from these plants. Each type of biogas plant (given 4 realistic mixes of excreta) is then evaluated for global warming potential, primary energy use and financial resource costs. Moving excreta through biogas plants, as opposed to simply reapplying on fields, to meet crop nutrient demands comes at a similar cost but the climate and primary energy savings are substantial. As much as 91% of phosphorus and 44% of nitrogen crop demand could be met via optimally transported excreta and the country would avoid about 1 450 kt of CO2-eq, save 3.6 TWh (13 000 tera-joules) of primary energy, and save 90 million euros per year. Substituting mineral fertilizers with recycled nutrients results in savings across all indicators, but the added energy and avoided greenhouse gas emissions associated with biogas production make a large difference in the attractiveness of nutrient recycling. Although the numeric values are theoretical, our results indicate that carefully coordinated and supported biogas production could help maximize multi-resource benefits.
Cassava produces about 10 times more carbohydrates than most cereals per unit area, and are ideal for production in marginal and drought prone areas. Cassava, which originated from tropical South America, is a perennial woody shrub with an edible root, which today is grown in tropical and subtropical regions of the world where it provides energy food and serves as a veritable source of food and income for over a billion people. This handbook provides new research on the production, consumption and potential uses of cassava.
Ph.D. is a mechanical engineer with experience in building systems energy efficiency, mechanical design in hydroelectric facilities, and solar thermal applications. Currently she provides technical support to the Northwest Combined Heat and Power Application Center with a focus in forest products, dairy digesters and wastewater treatment facilities. With the Washington State University Extension Energy Program, she provides technical assistance to commercial and industrial clients on energy system efficiency topics. Carolyn can be contacted by email at roosc@energy.wsu.edu.
A computerized empirical model for estimating the crop yield losses caused by machinery-induced soil compaction and the value of various countermeasures is presented, along with some examples of estimations made with it. The model is based mainly on results of Swedish field trials, and predicts the effects of compaction in a tillage system that includes mouldboard ploughing. It is designed for use at farm level and predicts four categories of effects: (1) Effects of recompaction after ploughing. The calculations are based on the wheel track distribution in the field and the relationship between “degree of compactness” of the plough layer and crop yield. (2) Effects of plough layer compaction persisting after ploughing. Crop yield losses are estimated from traffic intensity in Mgkm ha−1 (Mgkm = the product of the weight of a machine and the distance driven), soil moisture content, tyre inflation pressure and clay content. (3) Effects of subsoil compaction. The calculations are similar to those presented under point (2), but only vehicles with high axle load are considered. These effects are the most persistent. (4) Effects of traffic in ley crops. The estimations are based on wheel track distribution, soil moisture content and several other factors.
Energy-efficiency improvements resulting from the use of information technology for reheating furnaces in an integrated steel plant are evaluated. An energy-use model based on data recorded for 12 years is identified by using regression techniques. Links between efficiency changes and process modifications taken in the past are searched by comparing measured and model data. The model is also used to evaluate the impact on energy efficiency resulting from the installation of new measurement and control equipment. The results show that information technology has contributed to increased energy efficiency.