In today?s society there is an increasing demand for renewable energy sources such as sun and wind power. These sources are intermittent, and energy storage is therefore needed to ensure a constant power supply. This report compares pumped hydro energy storage (PHES), compressed air energy storage (CAES), flywheels, batteries, super magnetic energy storage (SMES) and hydrogen energy storage.The opportunities for further development are limited for PHES and CAES in comparison with the other technologies. Lithium-ion batteries and hydrogen energy storage are considered to have the most potential in the future.

Results have shown that flow batteries may be a solution in the future as an effective and environmental friendly method to an Energy storage system (ESS). The technology is reliable and has a high efficiency that comes with low energy losses and a long lifetime. The range of possible fields is suitable for cutting energy peaks in the power grid, by always have a ready and available energy storage that balances the production. By comparing the advantages of flow batteries with conventional batteries it is mainly the fact that they can conserve energy for a long time without being self-discharged thanks to that the storage capacity is in principle endless and limited by the size of the electrolytes tanks that makes them a great Energy storage system. The batteries won?t take any damage or decrease in performance when charging or discharging it or if you exhausts it to 100 % and leave it discharged for a long time.

Humanity stands before a huge challenge to lower its emissions of carbon dioxide and its use of energy at the same time as the global population is rising and the developing countries are being industrialized. A lot of newly built buildings are due to this challenge, designed to be more energy efficient but also use renewable energy resources instead of pollutant fossil fuels .Solar energy is one of the purest forms of energy that exists in abundant amounts, which is why it is most likely that it could come to play a major part in the future energy market. The main purpose of this report is to investigate the possibility to implement a sustainable energy system with solar thermal heat and  heat storage as main sources of energy in the neighborhood ?kvarteret Lagern?, which is the area where the old football stadium ?Rasunda Stadion? was located. New developments within different heat storage techniques have opened up new approaches to enable buildings an all year round heat supply from solar energy. This report will focus on heat storage in boreholes. At the present here is only a preliminary plan of how the neighborhood is supposed to be designed.

Norconsult AB has developed a solarhousing concept, a house designed for the warm climate in the Middle East andwith large quantities of solar panels installed. The cooling system for the house was designed in an earlier report, the purpose of this thesis is to investigate the possibility of short and long term storage of thermal energy via an underground energy storage volume.Two different designs of the storage and three different filling materials have been integrated into a model to simulate different cases. The first design consisted of pipes installed in the ground, without insulation. The second design consisted of an insulated concrete box installed to prevent thermal energy from the surrounding soil to flow towards the lower temperature regions within the storage. The three different filling materials were dry saudi sand, water saturated saudi sand and the filling material used by the client for energy storage in Sweden.The results from the simulations show that neither of the designs, regardless of the filling material, managed to extract enough thermal energy from the house to the ground to uphold the demands of indoor climate.

The constant need of energy is something that affects us all no matter our current situation. Whether we are driving our car to work, taking the elevator or using the oven to cook dinner we end up relying on energy. Our whole society is continuously striving to achieve a higher grade of efficiency and the process of supplying ourselves with energy is no exception. The importance of appliances in our everyday life cannot be exaggerated and thus the importance of their high efficiency.Efficiency is already a keyword in the appliance industry with labels, stars and numbers helping us choosing the most suitable option for the task ahead. No matter how efficient appliances often use pure electricity as their energy source.

With increased deployment ofintermittent renewable energy, such aswind and solar power, energy storagebecomes necessary to help reduceproduction peaks. Thermoelectric EnergyStorage is a method still in researchphase, which stores electricity in hotwater at a temperature of 120 ° C. Thisthesis aims to examine whether theThermoelectric Energy Storage would bepossible to integrate into existingpower generation such as a combined heatand power plant, and how the technologypotentially could function in theelectricity market. ThermoelectricEnergy Storage consists of a chargingprocess and a discharging process, bothoperating by the working fluid CO2. Toincrease the efficiency of theThermoelectric Energy Storage, wasteheat from the district heating networkis integrated.A model of the Thermoelectric EnergyStorage has been developed and it wascalculated by thermodynamic propertiesof the working fluid, CO2, in thevarious process steps.

Latent heat storage is a way to store thermal energy when a phase change material undergoes a phase change. The advantage of latent heat storage is the capability to store more energy per mass unit than other heat storage methods. The most commonly used phase change in latent heat storage is the transition between solid and liquid. Phase change materials can be divided into organics, inorganics and eutectics.In the Nordic electricity market the price of electricity is set every hour by Nordpool spot, which leads to price fluctuations because of changes in demand. The main goal of this report is to create a latent heat storage system in a single-family home and investigate the possibility to save money by charging the latent heat storage system when the price of electricity is low, and discharge when the price is high.The thermodynamic model consisted of a ?tube-in-tube? heat exchanger with phase change material in the outer tube and water as the heat transfer fluid in the inner tube.

This thesis considers the use of an oldrock cavern as thermal energy storage.With a large system of differentchillers a model was created to find anappropriate future system. There aremainly two trajectories to take. Eitheran installation of chillers needs to bemade or the rock cavern can be used tomeet the future demand of districtcooling in Solna, Sweden. Additionallythis thesis investigates the possibleuse of different techniques to utilizethe phase change energy of water.Simulation shows that it?s possible toutilize the phase-change energy of afluid; however it?s not economicallyfeasible due to the thermodynamiceffects on the Carnot cycle.

Geothermal energy can be extracted from an aquifer, where the groundwater is used as heatexchange medium while heat and cold are stored in the surrounding material in the aquiferand to some extent in the groundwater. Application of aquifer storage for the use ofgeothermal energy is mainly used in large scale facilities and is limited to sites with suitableaquifers in the form of ridges, sandstone and limestone aquifers.Löwenströmska hospital in the municipality of Upplands Väsby, north of Stockholm, islocated nearby the northern part of the Stockholm esker. This means that it can be profitableand environmentally beneficial for the hospital to examine the possibilities of aquifer storagein the esker material next to its property.The purpose of this master thesis has been to investigate if geothermal energy storage with aseasonal storage of heat and cold can be applied within Löwenströmska hospital?s propertyarea using groundwater modeling. A hydraulic groundwater model was constructed inMODFLOW based on a simplified conceptual model of the groundwater system.

Increased resource efficiency in an energy system could result in large economic and environmental benefits. Tekniska verken i Linköping AB (Tekniska verken) is responsible for the district heating network in Linköping. Their vision is to create the world?s most resource efficient region. An important step towards this vision is more efficient usage of produced heat, something which could be achieved through integration of a seasonal heat storage in the energy system.

The purpose with this study is to compare different systems of grain storage from a financial point of view. Grain that is supposed to be fed to laying hens. The systems that were compared were different airtight storage of grain and a system of conventional storage. To make this case study I choose to compare four different systems. In the case study there was one system with bin drying of the grain, two systems with airtight storage of the grain and one system where you buy dried grain during the season. I made several of capital investment appraisal where I found the cost of each system, then I took the cost and divided it with the total grain use and calculated the cost for each kilogram of grain, and also the cost of the feed. Then I compared the cost from my case study with the cost of buying feed. All the systems except for one, gave a lower cost for the hen feed than buying feed from a dealer The best system, witch were bin drying lower the cost with about 80 000:- SEK.

The purpose with this report is to examine how the implemented energy efficiency measures on Bokelundskolan in Växjö have had impact on the energy use. The measures which have been implemented are, new ventilation system, new heating system, optimized adjustment of the heating system, new windows with U-value 1.2 and lower window height, insulation under windows and in the crawl space. The school's energy use before and after rebuilding has been calculated with the calculation program, Vip-Energy 1.5.5.Calculations of energy use for the school with windows on U-value, 0.9 and 0.7 have also been done. The replacement of windows has been studied from a cost perspective. The conclusion is that the exchange of heat and ventilation system was the biggest contributor to reduced energy use on Bokelundskolan.

When the Swedish Forestry Act was changed in 1994, brushing of young stands became non mandatory. Since then the annual need for brushing in the country has increased by about 100 000 hectares per year. In later years the price for biomass energy has increased to the same level as pulp wood. The high price on biomass energy and the large areas of stands in the need of brushing has created a new market with its own technical, economical and environmental conditions. There is a development of various techniques to manage the forestry stands with late brushing.

Most of the portable electronic devices use a battery as a primary power source. Nowadays, when the applications are becoming smaller and smaller and more power efficient, the designer needs to concentrate more on reducing power consumption, using secondary power sources and introducing power storage devices. Multiple power source availability and a power storage device on the board will make the applications much more useful and efficient in everyday use. This thesis proposes a power supply unit (PSU) for wireless sensor platforms which is capable of supplying a sensor node with energy from multiple sources, as well as status information from the PSU. Present power storage devices, like electric double-layer capacitors (EDLCs) and batteries, have become more and more common as their characteristics have developed.

The sun is a huge energy source with great potential of providing energy to the heating of homes and other buildings in an environmentally sustainable manner. In order to provide buildings with energy from the sun it is necessary to transfer the energy supply over time to when the demand arises. By storing the heat in a seasonal storage, solar energy from the summer can be used in the winter when the demand for heating is greatest.Today's existing plants are mainly in Europe and particularly in Germany. These facilities are designed to supply heat demands greater than 400 MWh and covers about 40-50 % of this need which consists of energy for space heating and domestic hot water. How much of the heat demand that is covered, the solar fraction, is partly due to losses from the storage which in turn is connected to the surface area of the storage.