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The main task of this thesis is to find the ICT activator of a carotenoid spheroidenone in the pigment-protein complex LH1 of Rhodobacter sphaeroides. The ICT state is characterized by a red-shifted positive transient absorption signal around 750 - 800 nm. We hypothesize that the presence of the ICT state is associated with the pigment-protein interaction of a carotenoid keto group and specific amino acid in the protein. To perform the experiment, four mutant complexes with amino acids substitutions, which should result in decreased intensity of the ICT signal due to a weaker or missing pigment-protein interaction, were obtained and measured using femtosecond time resolved pump-probe spectroscopy.

Environment has become a major concern for society, which awareness of the importance of an environmentally respectful development has been growing during the last decades. Economic reasons have encompassed this transition to a more planet friendly conception of human development. In fact, this transition has been parallel to the growing prices of fossil fuels, facing a clear perspective of a shortage on its availability, insufficient to cope with a growing demand in the near future. Within this context, the role of renewable energies in order to stop depending on fossil fuels and to reduce greenhouse gases emissions has become crucial.   Because of its climate, heating represents a major source of energy consumption in Sweden, accounting for almost 60% of the residential and services sector energy use. Maximizing the efficiency of heating systems and using renewable, environmentally friendly and economically sustainable sources of energy may have an enormous impact on both environment and economy.   In this thesis the use of district heating and ground heat pump for a multi-dwelling building is evaluated, both from the economic and environmental points of view. Both are recognized to be efficient heating systems, allowing important savings of other sources of energy, and respectful with the environment.   An installation combining both district heating and ground heat pump, for a multi-dwelling building in Gävle has been analyzed. Different scenarios have been considered, and results obtained show that when installing a ground heat pump, both economic savings and CO2 emissions reduction are obtained. Annual economic savings account for 16,8% when providing 60% of the thermal energy with the ground heat pump, and considering the investment associated to the recent installation of a new heat pump (in the case studied, boreholes were already drilled), the payback time is 7,4 years. CO2 emissions reduction for a normal year reaches 34%. However, if we look at the wider picture of electricity and heat production from a community (local, regional, national or even international) point of view, several considerations have to be taken into account, which are discussed in the report.

In modern society in terms of economics and environmental impact, it is important to ensure that a company is as energy efficient as possible to reduce the amount of energy used. About 10 TWh of electricity used annually to pump drives in Swedish industry. Therefore, pumping system has great potential for energy savings. The objective of this report was to determine how much energy and money that can be saved with the insertion of variable speed drive to six pumps on Bleach plant 4 in Skutskär Mill. The work was performed with electrical measurements during one week, analysis of pump curves and the compilation of production data over a year. The results show that four of these six pumps were profitable and yielded an annual saving of 1172 MWh of electricity and 560 000 SEK. With an economic lifetime of 10 years and a discount rate of 6.8% the final result for the entire life-cycle savings became 3 355 000 SEK. The conclusion was that it is preferred to introduce variable speed drive on pumps with a motor power above 50 kW.

This thesis is an analysis of the simulated performance of two indirect heat pump assisted solar domestic hot water (i-HPASDHW) systems compared to two base systems: an electric domestic hot water (DHW) system and a traditional solar domestic hot water (SDHW) system. In this study, the four systems of interest were modeled in the TRNSYS software and simulated for a year in order to compare their performances. All of the systems had the same load profile and aimed to deliver domestic hot water at a constant temperature. This insured that each system delivered approximately the same amount of energy for the simulated period, thereby creating a common basis for comparison. The heat pump was introduced into the system configuration in an attempt to further improve the performance. Theoretically, the heat pump should send colder fluid to the collector which will extend the solar collection periods, both daily and seasonally when compared to the traditional SDHW system, as well as increase the efficiency of the collector. This will help to reduce the reliance on the electric auxiliary heaters and thus decrease the total electricity consumption. Both i-HPASDHW systems considered for this thesis collected more solar energy over the course of the simulated year compared to the base traditional SDHW system. They also consumed less electricity than the two base systems, which directly correlated to lower annual operating costs. It was concluded that the two i-HPASDHW systems analyzed in this study proved to be feasible configurations that performed more efficiently than the two base systems under the simulation conditions. However, it is important to understand that the results presented apply to the specific configurations. While the potential has been shown, prototypes must be built and tested with properly sized equipment for specific applications to get an accurate idea of the potential benefits. Also, equipment costs must be considered to determine payback periods for each system.

With the continued development of economy, the energy demand increases continually . The industry is interested in evaluating the technology of heat pump, with applications mostly for water heater. This thesis analyzes and compares the heating efficiency of electric heater, gas heater and heat pump heater . A fuzzy theory is employed to the developed heating algorithm to raise the efficiency of the heat pump heater and suppress the unnecessary heating at the high temperature. According to the experiment, the heat pump heater could reach 60% energy saving while gas heater could attain 23% in comparison with the electric heater under the same temperature, The system could work all year around and can provide users with water at a proper temperature. In the winter, COP of heat pump heater could reache 2.1~2.5 while in the summer around 2.61~2.95. The energy saving is obvious.