A multiregional input-output model representing the world in the year 2000 was constructed based on statistical data, and combined with process specific data on a primary aluminium supply chain, to create a model of the global primary aluminium industry. Using input-output methodology, total emissions of eight substances due to primary aluminium production, their size and origins, were estimated and expressed in terms of global warming potential (GWP) and acidification potential (AP). Simulations from 2000 to 2030 were run based on final demand estimates from external GDP projections and three assumed development scenarios. The baseline, scenario 0, assumed no changes in technologies or relative production and trade patterns - only the model's response to the expected change in final demand was analyzed. By contrast, both scenarios 1 and 2 assumed that the additional aluminium production predicted by the baseline would be produced exclusively in China. Scenario 2 employed the added assumption that the Norwegian aluminium production would experience a steady decline from its 2000 level to zero by 2030. The baseline scenario showed rapidly increasing aluminium output towards 2030, following the expected GDP developments. Emissions followed the same trend, increasing about 3.3 times over the three decades. As for total cradle-to-gate impacts of primary aluminium production, the model showed large variations from one region to another. Emissions per ton of Chinese primary aluminium were high relative to most other regions, hence the total global GWP and AP from primary aluminium production rose more rapidly in scenarios 1 and 2 than in scenario 0. By 2030, the GWP in scenarios 1 and 2 were 11.4% and 12.5 higher than in the baseline, while AP were 50.0 and 51.9 higher.

Subsea processing can make production from otherwise unprofitable fields profitable. In subsea processing controlled cooling of the process fluid will often be required. Robust and simple solutions are desirable in subsea processing. Coolers that rely on natural convection from the surrounding seawater are therefore interesting, but control of the process fluid outlet temperature is hard to obtain in such coolers. In this study a calculation model for subsea coolers has been developed. The commercial software MATLAB has been used for developing a program. Heat transfer and frictional pressure drop correlations have been studied and recommendations are made for the model. The model is based on tubes in parallel, and the tubes can be oriented vertically or horizontally. The program allows for open, semi-open and closed arrangements on the waterside, and both natural and forced convection is implemented. The program has been tested through simulations of two test cases and found to be performing as desired.

The performance of a hot wire probe with three wires is investigated for two different flow cases. The wires are made of a platinum/rhodium alloy, and has a diameter of 5 micrometer. The three wires make a probe volume with acrossection of approximately 5 mm. A cosinus fit using the effective angle method gives a deviation of plus/minus 1 degree for a variation of yaw angle equal to plus/minus 20 degrees. First the probe was tested in a fully developed turbulent pipe flow, for Re_D = 10^5. Good results were obtained for |y/R|<0.8, both for mean velocities and turbulent stresses. Closer to the wall the mean flow gradient was to large relative to the probe resolution, giving large errors. The second flow case was a cylinder wake. A traverse of the flow at x/D = 10 was performed at Re_D = 3*10^3. The mean velocities and turbulent stresses was partly found to be in qualitative agreement with results found in litterature. The shear stresses uw and vw were however found to be unphysically large, this is belived to be due to the velocity gradient in the wake. Conditional averaging of the wake results with respect to shedding frequency was also conducted.

The process used by the Norwegian company Hydro for making Vinyl Chloride Monomer (VCM) from natural gas and sodium chloride has been studied. A three dimensional CFD model representing the firebox of the EDC cracker has been developed using the commercial CFD tool Fluent. Heat to the cracker is delivered by means of combustion of a fuel gas consisting of methane and hydrogen. In the developed CFD model used in this work, the combustion reaction itself is omitted, and heat is delivered by hot flue gas. With the combustion reaction left out, the only means of tuning the CFD model is through the flue gas inlet temperature. With the flue gas inlet temperature near the adiabatic flame temperature, the general temperature level of the EDC cracker was reported to be too high. The outer surface temperature of the coil was reported to be 3-400 K higher than what was expected. By increasing the mass flow of flue gas and decreasing the temperature, the net delivered heat to the firebox was maintained at the same level as the first case, but the temperature on the coil was reduced by 100-150 K. Further reductions in the flue gas inlet temperature and modifications in the mass flow of flue gas at the different burner rows, eventually gave temperature distributions along the reaction coil, and flue gas and refractory temperatures, that resemble those in the actual cracker. The one-dimensional reactor model for the cracking reaction represents the actual cracker in a satsifactorily manner. The cracking reaction was simulated using a simple, global reaction mechanism, thus only the main components of the process fluid, EDC, VCM and HCl, can be studied. The model is written in a way suitable for implementation of more detailed chemical reaction mechanisms. The largest deviation in temperature between measured and simulated data are about 5%. At the outlet the temperature of the process fluid is equal to the measured data. The conversion of EDC out of the firebox is assumed to be 50 wt-%, this value is met exactly by the model.

This master thesis describes a quadratic programming model used to calculate the spot prices in an efficient multi-area power market. The model has been adapted to Northern Europe, with focus on Denmark West and the integration of large quantities of wind power. In the model, demand and supply of electricity are equated, at an hourly time resolution, to find the spot price in each area. Historical load values are used to represent demand which is assumed to be completely inelastic. Supply is modeled according to the type of generation: Thermal generators are represented by piecewise linear, upward sloping, marginal cost curves. Historical wind generation data is used to model the fluctuating wind power output, and wind power is considered to have zero marginal cost. Hydro power is modeled by one aggregate reservoir for Norway and one for Sweden; the marginal cost of hydro power is set as a function of the difference between the reservoir level and the historical median reservoir level. Additionally, decentral combined heat and power plants in Denmark are considered to operate irrespective of the market. Six separate price areas constitute the model: Denmark West, Denmark East, Norway, Sweden/Finland, Germany, and Central Europe. The areas are modeled as having no internal bottlenecks and are connected by tie-lines constrained by active power limits. This report quantifies the impact the installed wind power capacity has on the power price in Denmark West by scaling up the wind power output in the model. Because wind power has a marginal cost close to zero, it will force prices down. The effect will be most prominent during high wind speed hours in a power system with substantial amounts of wind power. Results show that the impact is modest; average power prices fall by only 10% if the installed wind power capacity is doubled, and thermal generation will set the power price in all hours until wind energy exceeds 50% of domestic demand in Denmark. Since prices fall the most during hours with high wind power output, income to wind turbine owners will decline quickly as the installed capacity becomes large. The effect is most pronounced at wind energy shares above 40%, thereafter the income -- per MWh sold -- falls rapidly. In absence of government subventions, this effect will limit the economically viable level of installed wind power capacity. Expansion of the cross-border transmission capacity and higher thermal generation costs can both help offset the income reduction to wind turbine owners from higher wind power penetration. Alone, a 30% increase in thermal generation costs can allow 50% of wind energy and still retain todays income to wind turbine owners. Use of the Norwegian hydro reservoirs to balance out fluctuations in wind power output is found to stabilize and reduce the price. This benefits both consumers and wind turbine owners in Denmark. Expansion of transmission capacity to Norway will further stabilize the price; a new 1000MW cable lets the Danish market easily accomodate 50% wind energy. With lower and more volatile prices as a result of high wind power penetration, a load can profit by being flexible. Water electrolysis is one such load; it uses electricity to produce hydrogen, and production can quickly be ramped up and down in accordance with the power price. Presently, steam methane reforming is the least expensive method of producing hydrogen, but with higher wind power penetration, electrolysis might become competitive. Using a previously developed model to assess the cost of electrolysis, in combination with the power market model developed here, this report finds that wind energy must exceed 85% of domestic demand in Denmark, combined with higher natural gas prices, for electrolysis to break even with steam methane reforming.

A measurement of the hydraulic turbine efficiency at the Vessingfoss hydro power station by the thermodynamic method has been attempted, but has not given the desired results. Two problems have been encountered. The high pressure side temperature measurements show an abnormal scatter resulting in standard deviations of sy=0.05ºC. The reason for the scatter may be temperature layers in the reservoir lake Nesjø. This theory has been investigated, but needs further work. The other problem has been the mechanical strength of the low pressure side collector probes. Two different collectors have been tried, and both have broken down. The second attempt was made with a collector design based on wire rope, which failed because the turnbuckles were under-dimensioned. With proper dimensions, this solution is interesting in the future, as it was easy to install and may contribute to lose collector weight. The relative turbine efficiency has been calculated based on pressures and levels measured during the thermodynamic test. An uncertainty analysis of the result has been carried out. The head loss has been calculated based on technical drawings of the penstock and loss coefficients from the literature.

A multi-reactor, multi-temperature, waste-heat driven biomass thermochemical converter is proposed and simulated in the process simulation tool Aspen Plus™. The thermochemical converter is in Aspen Plus™ integrated with a gas turbine power cycle and a combined fuel cell/gas turbine power cycle. Both power cycles are recuperative, and supply the thermochemical converter with waste heat. For result comparison, the power cycles are also integrated with a reference conventional single-reactor thermochemical converter, utilizing partial oxidation to drive the conversion process. Exergy analysis is used for assessment of the simulation results. In stand-alone simulation, the proposed thermochemical shows high performance. Cold gas efficiency is 108.0% and syngas HHV is 14.5 MJ/kg on dry basis. When integrated with the gas turbine power cycle, the proposed converter fails to improve thermal efficiency of the integrated cycle significantly, compared to reference converter. Thermal efficiency is 41.8% and 40.7%, on a biomass HHV basis, with the proposed and the reference converter respectively. This is despite superior cold gas efficiency for the proposed converter, and the gas turbine cycle is found not to be able to properly take advantage of the high chemical energy in the syngas of the proposed converter. When integrated with the combined fuel cell/gas turbine power cycle, the proposed converter significantly improves the thermal efficiency of the integrated cycle, compared to the reference converter. Thermal efficiency is 56.0% and 51.2%, on a biomass HHV basis, with the proposed and the reference converter respectively. The fuel cell is found to be able to take advantage of the high chemical energy in the syngas of the proposed converter, which is the main cause of increase in thermal efficiency. Operation of the proposed thermochemical converter is found to be feasible at a wide range of operating conditions, although low operating temperatures in the converter may cause problems at very high carbon conversion ratios.

In this work, a 23-1 designed experiment has been performed to evaluate the effect of selected operating conditions on PEMFC performance and durability. Relative humidity, clamping pressure and back pressure were studied at two levels for Gore MEAs and GDLs. Two replicated experiments were performed. An ON/OFF test cycle was used to accelerate degradation. Total duration of the tests, after a break in procedure suggested by Gore, was ten days. In addition to sampling of voltage and current response and ohmic resistance, effluents were manually sampled from both electrodes every 24 hours and analyzed. Experiments with low humidification levels showed inferior durability. The combination of high relative humidity (100 %), high clamping pressure (10 barg) and high back pressure (1.5barg) result in the best performance and the lowest degradation rate. Results indicate that relative humidity is important both for performance and durability. Generally, fluoride emission rates (FER) showed an increasing trend with time. Higher rates were observed at the cathode. For the experiment with low relative humidity (25 %), low clamping pressure (5 barg) and high back pressure (1.5 barg) FER was significantly higher compared to the other experiments. For all tests the sulfur emission rates (SER) are initial high. Rates are higher at the anode. For the experiment with high relative humidity, low clamping pressure and no back pressure, the SER was significantly higher than for the other experiments. The sustained high levels of sulfur are probably a result of sulfuric acid residue from production of the MEA and/or GDL. High humidification of gases appears to more effectively wash out the sulfur.

Coal is the most common fossil resource for power production worldwide and generates 40% of the worlds total electricity production. Even though coal is considered a pollutive resource, the great amounts and the increasing power demand leads to extensive use even in new developed power plants. To cover the world's future energy demand and at the same time limit our effect on global warming, coal fired power plants with CO2 capture is probably a necessity. An Integrated Gasification Combined Cycle (IGCC) Power Plant is a utilization of coal which gives incentives for CO2 capture. Coal is partially combusted in a reaction with steam and pure oxygen. The oxygen is produced in an air separation process and the steam is generated in the Power Island. Out of the gasifier comes a mixture of mainly H2 and CO. In a shift reactor the CO and additional steam are converted to CO2 and more H2. Carbon dioxide is separated from the hydrogen in a physical absorption process and compressed for storage. Hydrogen diluted with nitrogen from the air separation process is used as fuel in a combined cycle similar to NGCC. A complete IGCC Power Plant is described in this report. The air separation unit is modeled as a Linde two column process. Ambient air is compressed and cooled to dew point before it is separated into oxygen and nitrogen in a cryogenic distillation process. Out of the island oxygen is at a purity level of 95.6% and the nitrogen has a purity of 99.6%. The production cost of oxygen is 0.238 kWh per kilogram of oxygen delivered at 25°C and 1.4bar. The oxygen is then compressed to a gasification pressure of 42bar. In the gasification unit the oxygen together with steam is used to gasify the coal. On molar basis the coal composition is 73.5% C, 22.8% H2, 3.1% O2, 0.3% N2 and 0.3% S. The gasification temperature is at 1571°C and out of the unit comes syngas consisting of 66.9% CO, 31.1% H2, 1.4% H2O, 0.3% N2, 0.2% H2S and 0.1% CO2. The syngas is cooled and fed to a water gas shift reactor. Here the carbon monoxide is reacted with steam forming carbon dioxide and additional hydrogen. The gas composition of the gas out of the shift reactor is on dry basis 58.2% H2, 39.0% CO2, 2.4% CO, 0.2% N2 and 0.1% H2S. Both the gasification process and shift reactor is exothermal and there is no need of external heating. This leads to an exothermal heat loss, but parts of this heat is recovered. The gasifier has a Cold Gas Efficiency (CGE) of 84.0%. With a partial pressure of CO2 at 15.7 bar the carbon dioxide is easily removed by physical absorption. After separation the solvent is regenerated by expansion and CO2 is pressurized to 110bar to be stored. This process is not modeled, but for the scrubbing part an energy consumption of 0.08kWh per kilogram CO2 removed is assumed. For the compression of CO2, it is calculated with an energy consumption of 0.11kWh per kilogram CO2 removed. Removal of H2S and other pollutive unwanted substances is also removed in the CO2 scrubber. Between the CO2 removal and the combustion chamber is the H2 rich fuel gas is diluted with nitrogen from the air separation unit. This is done to increase the mass flow through the turbine. The amount of nitrogen available is decided by the amount of oxygen produced to the gasification process. Almost all the nitrogen produced may be utilized as diluter except from a few percent used in the coal feeding procedure to the gasifier. The diluted fuel gas has a composition of 50.4% H2, 46.1% N2, 2.1% CO and 1.4% CO2. In the Power Island a combined cycle with a gas turbine able to handle large H2 amounts is used. The use of steam in the gasifier and shift reactor are integrated in the heat recovery steam generator (HRSG) in the steam cycle. The heat removed from the syngas cooler is also recovered in the HRSG. The overall efficiency of the IGCC plant modeled is 36.8%. This includes oxygen and nitrogen production and compression, production of high pressure steam used in the Gasification Island, coal feeding costs, CO2 removal and compression and pressure losses through the processes. Other losses are not implemented and will probably reduce the efficiency.

In 2003 the European Commission introduced the Directive 2003/54/EC and Regulation 1228/2003/EC which increased the focus on the liberalization of the European electricity market. The international electricity trade has increased and created new challenges related to cross-border transmission and compensation mechanisms. The focus of the report has been to discuss the development of the electricity market in Europe, and the status of international exchange. The report also discusses the concept of cross-border trade and transit, and investigates a proposed ITC model and whether correct investment incentives are given. Price data from the main power exchanges in Europe indicate that the market is experiencing increasingly integration and efficiency. There has also been a trend towards market based congestion management methods. Regional markets have successfully developed in Spain and Portugal (the Iberian market) and between France, Belgium and The Netherlands (the Trilateral Market Coupling, TLC). Further plans for regional coupling are also underway (see chapter 5. The most common definition of transit is the one adopted by ETSO (Association of European Transmission System Operators), where transit is defined as the minimum between exports and imports. This definition could create opportunities for market participants to manipulate transit income (discussed in chapter 5.3). The Inter-TSO compensation (ITC) model used in this report is based on the With-and-Without transit algorithm. The model only focuses on costs and load flow, and do not include market incentives or evaluation of benefits. The model bases the compensation calculation on the transit term, which can lead to misguided identification of network responsibility. Two scenarios were compared with a base case scenario in order to identify possible investment incentives. The first scenario included a situation where one of the cross-border lines in the network was constrained. Results from this simulation indicate that the transmission system operators involved would experience increased ITC payment, and therefore not receive investment incentives. The TSOs involved would benefit from the bottleneck in form of increased revenue (assuming Cost-Of-Service regulation). In the second scenario an extra cross-border line was implemented, and the situation was compared to the base case. The results from this simulation show that the TSOs involved would receive a positive effect in form of reduced ITC cost. The ITC mechanism would in this case be in line with the European Commission’s Regulation 1228/2003/EC, and give the involved TSOs correct investment incentives. The lack of correlated results in these two cases indicates that the ITC mechanism (in this case modeled by the WWT algorithm) cannot be regarded as relevant from an investment incentive perspective (more information found in chapter 7.3).