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Abstract: This paper investigates the economics of integrated gasification polygeneration (IG-PG) facilities and assesses under which market conditions flexible facilities outperform static facilities. In this study, the facilities use Eucalyptus wood pellets (EP), torrefied wood pellets (TOPS) and Illinois #6 coal as feedstock to produce electricity, FT-liquids, methanol and urea. All facilities incorporate CCS. The findings show production costs from static IG-PG facilities ranging between 12 and 21€/GJ using coal, 19–33€/GJ using TOPS and 22–38€/GJ using EP, which is above the average market prices. IG-PG facilities can become competitive if capital costs drop by 10%–27% for coal based facilities. Biomass based facilities will need lower biomass pellet prices or higher CO2 credit prices. Biomass becomes competitive with coal at a CO2 credit price of 50–55€/t CO2. Variations in feedstock, CO2 credit and electricity prices can be offset by operating a feedstock flexible IG-PG facility, which can switch between coal and TOPS, thereby altering its electricity production. The additional investment is around 0.5% of the capital costs of a dedicated coal based IG-PG facility. At 30€/t CO2, TOPS will be the preferred feedstock for 95% of the time at a feedstock price of 5.7€/GJ. At these conditions, FT-liquids (gasoline/diesel) can be produced for 15.8€/GJ (116 $/bbl). Historic records show price variations between 5.7 and 7.3€/GJ for biomass pellet, 1.0–5.6€/GJ for coal and 0–32€/t CO2. Within these price ranges, coal is generally the preferred feedstock, but occasionally biomass is preferred. Lower biomass prices will increase the frequency of switching feedstock preference from coal to biomass, raising the desire for flexibility. Of the three investigated chemicals, an IG-PG facility producing FT-liquids benefits the most from flexibility. Our study suggests that if the uncertainty in commodity prices is high, a small additional investment can make flexible IG-PG facilities attractive. [Copyright &y& Elsevier]

Abstract: This article investigates technical possibilities and performances of flexible integrated gasification polygeneration (IG-PG) facilities equipped with CO2 capture for the near future. These facilities can produce electricity during peak hours, while switching to the production of chemicals during off-peak hours. Several simulations were performed to investigate the influence of substituting feedstock and production on IG-PG facility output, load and efficiency. These simulations were done using a detailed AspenPlus simulation model of a Shell entrained flow gasifier combined with conversion facilities. In this model carbon-rich feedstocks (oil residues, coal and biomass) were converted to a variety of products (H2, electricity, FT-liquids, methanol and urea) using state-of-the-art technology. The size of the gasifier was limited to the equivalent of 2000MWth Il #6 coal input. Overall efficiency of the simulated non-flexible configurations to convert pure coal or pure wood pellets to electricity (40%HHV vs 38%HHV), FT-liquids (60%HHV vs 55%HHV), methanol (53%HHV vs 49%HHV) or urea (51%HHV vs 47%HHV) are in good agreement with the literature. Using torrefied wood pellets instead of pure wood pellets reduces the penalty drop in efficiency compared to coal. Moreover, torrefied wood pellets have superior energetic density, handling and feeding compared to wood pellets. In this analysis, the H2:CO ratio of the sweet syngas was fixed to match FT-liquids criterion. As a result, overall CO2 capture rates are low, around 56–65%, depending on the feedstock used. Still, especially with FT-liquids and methanol production, CO2 emissions at the facility are significantly reduced; less than 20% of the carbon feedstock entering the facility is emitted with the flue gas. Applying biomass and CO2 capture shows great opportunities to produce CO2-neutral electricity or chemicals. When the biomass fraction exceeds 40% on an energy basis, production is CO2-neutral, independent of what is produced. Biomass can be co-fed up till 50% on an energy basis. Higher fractions cause significant fouling on cooling equipment. A small part-load penalty is observed during the substitution of coal by biomass. When changing from pure coal to pure wood pellets, the power case suffers a 2.5% efficiency drop, while all three chemical cases have an efficiency drop of less than 1%. At the same time total output is reduced to 67–69%, mainly because of the lower energy density of biomass. By over-dimensioning the gasifier and gas cleanup and optimisation section this drop can be eliminated. The syngas can be tailored to the desired composition regardless of the used feedstock. Therefore, the chemical conversion sections only have to cope with a reduction in syngas flow and not with a change in syngas composition. Altering production between chemicals and electricity is possible, although the load of the conversion sections should remain between 40% and 100% to prevent operational problems. This gives a high degree of flexibility. Complete substitution between chemical and power production while using the same feedstock is possible for the methanol and urea cases. The FT-liquids case is restricted to 60–100% load of the chemical conversion section to prevent that the gas turbine load is reduced below 40%. The economic aspects of flexible IG-PG facilities are addressed in part B. [Copyright &y& Elsevier]

Abstract: Solar cell performance parameters (open circuit voltage, short circuit current, fill factor and efficiency) are derived for different solar cell types for the irradiance range 0.1–1000W/m2. Also it is demonstrated how spectral mismatch factors for indoor lighting conditions are calculated. The presented methods and particular results may aid product designers in selecting appropriate solar cells for Product Integrated PV (PIPV) operated indoors and allow for more certainty in energy balance estimations of PIPV design concepts. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we show that photovoltaic (PV) energy yields can be simulated using standard rendering and ray-tracing features of Computer Aided Design (CAD) software. To this end, three-dimensional (3-D) sceneries are ray-traced in CAD. The PV power output is then modeled by translating irradiance intensity data of rendered images back into numerical data. To ensure accurate results, the solar irradiation data used as input is compared to numerical data obtained from rendered images, showing excellent agreement. As expected, also ray-tracing precision in the CAD software proves to be very high. To demonstrate PV energy yield simulations using this innovative concept, solar radiation time course data of a few days was modeled in 3-D to simulate distributions of irradiance incident on flat, single- and double-bend shapes and a PV powered computer mouse located on a window sill. Comparisons of measured to simulated PV output of the mouse show that also in practice, simulation accuracies can be very high. Theoretically, this concept has great potential, as it can be adapted to suit a wide range of solar energy applications, such as sun-tracking and concentrator systems, Building Integrated PV (BIPV) or Product Integrated PV (PIPV). However, graphical user interfaces of ‘CAD-PV’ software tools are not yet available. [Copyright &y& Elsevier]

The technical and economical feasibility of CO2 sequestration in deep coal layers combined with enhanced coalbed methane (ECBM) production in the Netherlands has been explored. Annually, 3.4 Mtonne CO2 from chemical installations can be delivered to sequestration locations at 15 €/tonne and another 55 Mtonne from power generating facilities at 40–80 €/tonne. Four potential ECBM areas have been assessed, of which Zuid Limburg is the best location for a test site, while the Achterhoek is more suitable for future large-scale CO2 sequestration. Between 54 Mtonne and 9 Gtonne CO2 can be sequestered in the four areas together, heavily depending on available technology for accessing the coal seams. At the same time, between 0.3 and 60 EJ of coalbed methane can be produced. The optimal configuration may have 1000 m spacing between production wells, and extreme inseam drilling. The price of coalbed methane may become competitive with natural gas when a bonus for CO2 sequestration is applied of about 25 €/tonne. For the long term, on-site hydrogen or power (SOFC) production with direct injection of produced CO2 seems most attractive. Further study is required, most notably more accurate geological surveys, assessment of drilling costs in Dutch context, and environmental impacts of ECBM. [Copyright &y& Elsevier]

Abstract: This work assesses the viability of regional biomass chains by comparing the economic performance of potential bioenergy crops with the performance of current agricultural land uses. The biomass chains assessed are ethanol production from Miscanthus and from sugar beet in the North of the Netherlands. The competitiveness of bioenergy crops is assessed by comparing the Net Present Value (NPV) of perennial crops, current rotations, and rotation schemes which include additional years of sugar beet. The current land use and soil suitability for present and bioenergy crops are mapped using a geographical information system (GIS) and the spatial distribution of economic profitability is used to indicate where land use change is most likely to occur. Bioethanol production costs are then compared with petrol costs. The productions costs comprise costs associated with cultivation, harvest, transport and conversion to ethanol. The NPVs and cost of feedstock production are calculated for seven soil suitability classes. The results show that bioenergy crops are not competitive with current cropping systems on soils classed as “suitable”. On less suitable soils, the return on intensively managed crops is low and perennial crops achieve better NPVs than common rotations. Our results showed that minimum feedstock production costs are 5.4€/GJ for Miscanthus and 9.7€/GJ for sugar beet depending on soil suitability. Ethanol from Miscanthus (24€/GJ) is a better option than ethanol from sugar beet (27€/GJ) in terms of costs. The cost of bioethanol production from domestically cultivated crops is not competitive with petrol (12.34€/GJ) production under current circumstances. We propose that the method demonstrated in this study, provides a generic approach for identifying viable locations for bioenergy crop production based on soil properties and current land use. [Copyright &y& Elsevier]

Abstract: The feasibility of deploying a socio-economic and environmental impact analysis for large-scale bioenergy production on a regional level is analyzed, based on a set of defined criteria and indicators. The analysis is done for La Pampa province in Argentina. The case study results in conclusions in how far the criteria can be verified ex ante based on available methodologies and data sources. The impacts are analyzed for two bioenergy chains (soybeans and switchgrass) for a set of defined land use scenarios. The carbon stock change for switchgrass ranges from 0.2 to 1.2tonC/ha/year and for soybean from −1.2 to 0tonC/ha/year, depending on the scenario. The GHG emission reduction ranges from 88% to 133% for the switchgrass bioenergy chain (replacing coal or natural gas) and from 16% to 94% for the soybean bioenergy chain (replacing fossil fuel) for various lifetime periods. The annual soil loss, compared to the reference land use system is 2–10ton/ha for the soybean bioenergy chain and 1–2ton/ha for the switchgrass bioenergy chain. In total, nine sustainability principles are analyzed. In the case of switchgrass, most environmental benefits can be achieved when produced on suitable land of abandoned cropland. Soybean production for bioenergy shows a good overall sustainability performance if produced on abandoned cropland. The production of switchgrass on degraded grassland shows socio-economic and environmental benefits, which is not the case for soybean production. The production of bioenergy production on non-degraded grassland is not preferred. It is concluded that the scenario approach enables understanding of the complexity of the bioenergy chain and the underlying factors influencing the sustainability principles. It is difficult to give ex ante a final conclusion whether a bioenergy chain is sustainable or not as this depends not only on the previous land use system but also on other factors as the selection of the bioenergy crop, the suitable agroecological zone and the agricultural management system applied. The results also imply that it is possible to steer for a large part the sustainability performance of a bioenergy chain during project development and implementation. Land use planning plays a key role in this process. [Copyright &y& Elsevier]

Abstract: This study focuses on the economic feasibility for large-scale biomass production from soybeans or switchgrass from a region in Argentina. This is determined, firstly, by estimating whether the potential supply of biomass, when food and feed demand are met, is sufficient under different scenarios to 2030. On a national level, switchgrass has a biomass potential of 99×106 (1.9 EJ) to 243×106 tdm (4.5 EJ)/year depending on the scenario. Soybean (crude vegetable oil content) production for bioenergy has a potential of 7.1×106 (0.25 EJ) to 13.8×106 tdm (0.5 EJ)/year depending on the scenario. The most suitable region (La Pampa province) to cultivate energy crop production is selected based on a defined set of criteria (available land for biomass production, available potential for both crops, proximity of logistics and limited risk of land use competition). The available potential for bioenergy in La Pampa ranges from 1.2×105 to 1.8×105 tdm/year for soybean production (based on vegetable oil content) and from 6.3×106 to 18.2×106 tdm/year for switchgrass production, depending on the scenario. Bioenergy chains for large-scale biomass production for export or for local use are further defined to analyse the economic performance. In this study, switchgrass is converted to pellets for power generation in the Netherlands or for local heating in Argentina. Soybeans are used for biodiesel production for export or for local use. Switchgrass cultivation costs range from 33–91US$/tdm (1€=1.47 US$ based on 19 February 2008). Pellet production costs are 58–143US$/tdm for local use and 150–296US$/tdm until delivery at the harbour of Rotterdam. Total conversion costs for electricity in the Netherlands from switchgrass pellets range from 0.06–0.08US$/kWh. Heating costs in Argentina from switchgrass pellets range from 0.02–0.04US$/kWh. Soybean cultivation costs range from 182–501US$/tdm depending on the scenario. Biodiesel production costs are 0.3–1.2 US$/l for local use and 0.5–1.7 US$/l after export to the Netherlands. Key parameters for the economic performance of the bioenergy chains in La Pampa province are transport costs, cultivation costs, pre-processing and conversion costs and costs for fossil fuels and agricultural commodities. [Copyright &y& Elsevier]

Abstract: Measured and modelled JV characteristics of crystalline silicon cells below one sun intensity have been investigated. First, the JV characteristics were measured between 3 and 1000W/m2 at 6 light levels for 41 industrially produced mono- and multi-crystalline cells from 8 manufacturers, and at 29 intensity levels for a single multi-crystalline silicon between 0.01 and 1000W/m2. Based on this experimental data, the accuracy of the following four modelling approaches was evaluated: (1) empirical fill factor expressions, (2) a purely empirical function, (3) the one-diode model and (4) the two-diode model. Results show that the fill factor expressions and the empirical function fail at low light intensities, but a new empirical equation that gives accurate fits could be derived. The accuracy of both diode models are very high. However, the accuracy depends considerably on the used diode model parameter sets. While comparing different methods to determine diode model parameter sets, the two-diode model is found to be preferred in principle: particularly its capability in accurately modelling VOC and efficiency with one and the same parameter set makes the two-diode model superior. The simulated energy yields of the 41 commercial cells as a function of irradiance intensity suggest unbiased shunt resistances larger than about 10kΩcm2 may help to avoid low energy yields of cells used under predominantly low light intensities. Such cells with diode currents not larger than about 10−9 A/cm2 are excellent candidates for Product Integrated PV (PIPV) appliances. [Copyright &y& Elsevier]

Abstract: A solar powered wireless computer mouse (SPM) was chosen to serve as a case study for the evaluation and optimization of industrial design processes of photovoltaic (PV) powered consumer systems. As the design process requires expert knowledge in various technical fields, we assessed and compared the following: appropriate selection of integrated PV type, battery capacity and type, possible electronic circuitries for PV-battery coupling, and material properties concerning mechanical incorporation of PV into the encasing. Besides technical requirements, ergonomic aspects and design aesthetics with respect to good “sun-harvesting” properties influenced the design process. This is particularly important as simulations show users can positively influence energy balances by “sun-bathing” the PV mouse. A total of 15 SPM prototypes were manufactured and tested by actual users. Although user satisfaction proved the SPM concept to be feasible, future research still needs to address user acceptance related to product dimensions and user willingness to pro-actively “sun-bath” PV powered products in greater detail. [Copyright &y& Elsevier]

Abstract: With its increasing use, the production costs of primary forest fuel (PFF) have declined over the last three decades in Sweden. The aims of this study are to quantify cost reductions of PFF production as achieved in Sweden over time, to identify underlying reasons for these reductions, and to determine whether the experience curve concept can be used to describe this cost reduction trend. If applicable, the suitability of this concept for future cost reduction analysis and for use in other countries is explored. The analysis was done using average national PFF price data (as a proxy for production costs), a number of production cost studies and data on annual Swedish production volumes. Results show that main cost reductions were achieved in forwarding and chipping of PFF, largely due to learning-by-doing, improved equipment and changes in organization. The price for wood fuel chips does follow an experience curve from 1975 to 2003 (over nine cumulative doublings). The progress ratio (PR) is calculated at 87%. However, given the uncertainty in data on PFF price and annual production volumes, the PR may range between 85% and 88%. It is concluded that in combination with the available supply potential of PFF and with bottom-up assessment of cost reduction opportunities, experience curves can be valuable tools for assessing future PFF production cost development in Sweden. A methodological issue that needs to be further explored is how learning took place between Sweden and other countries, especially with Finland, and how the development of technology and PFF production in these countries should be combined with the Swedish experiences. This would allow the utilization of the experience curve concept to estimate cost developments also in other countries with a large potential to supply PFF, but with less developed PFF supply systems. [Copyright &y& Elsevier]