Seabed sediment : a natural seasonal heat storage feasibility study

The new discovery among renewable energy resources, seabed sediment, has been utilised as a heat source for 42 houses in Vaasa since 2008. Sediment heat is annually loaded by the Sun. In this study the amount of annually charged energy is estimated. The difference of sediment temperatures between the coldest and the warmest month during the year is a key value in the approximation of the loaded energy. Sediment temperatures are measured once per month via optical cable by distributed temperature sensing (DTS) method. The monitoring period is three years, 2014–2016. The estimation of incoming energy (575 MWh) versus known exploited energy (560 MWh) is reasonable. Despite of the extraction this seasonal heat storage in the seabed of the Baltic Sea seems to reload well annually.fi=vertaisarvioitu|en=peerReviewed

Reliable Renewable Hybrid Energy Solutions

Worldwide studies, including the Paris agreement, show that it is necessary to reduce dependency on the non-renewable energy sources and fossil fuels such as oil and coal. Transition to renewable energy is evident, and different reliable renewable energy systems are needed. The energy production with renewable energy sources is typically non-continuous when using only a single technique. This can be avoided by using a hybrid system and/or seasonal storage. This study introduces several hybrid systems and examples of storages operating mainly in Finland most of them in co-operation with University of Vaasa. Hybrid renewable energy systems (HRES) can be implemented in multiple different ways, scope varies from larger energy villages and other residential areas to single buildings. The amount of renewable energy generated by any HRES depends on both the technology and the meteorology. Some energy sources like different forms of geoenergy (geothermal energy) are available around the year. Instead, some renewable energy sources like solar and wind are often season dependent energy. To ensure constant production in HRES for the electric grid or the heating network, the energy storage or backup energy systems are in almost all cases needed. Advantages of the hybrid techniques are reliable, constant energy production and scalable energy production. When designing a hybrid system it also needs to be solved, what to do with the excess energy; whether to deliver it to the grid, use the dump loads or the storage systems.© SDEWES Centre, Conference on sustainable development of energy, water and environment systems.fi=vertaisarvioitu|en=peerReviewed

Strategies for lipid production improvement in microalgae as a biodiesel feedstock

In response to the energy crisis, global warming, and climate changes, microalgae have received a great deal of attention as a biofuel feedstock. Due to a high lipid content in microalgal cells, microalgae present as a promising alternative source for the production of biodiesel. Environmental and culturing condition variations can alter lipid production as well as chemical compositions of microalgae. Therefore, application of the strategies to activate lipid accumulation opens the door for lipid overproduction in microalgae. Until now, many original studies regarding the approaches for enhanced microalgal lipid production have been reported in an effort to push forward the production of microalgal biodiesel. However, the current literature demonstrates fragmented information available regarding the strategies for lipid production improvement. From the systematic point of view, the review highlights the main approaches for microalgal lipid accumulation induction to expedite the application of microalgal biodiesel as an alternative to fossil diesel for sustainable environment. Of the several strategies discussed, the one that is most commonly applied is the design of nutrient (e.g., nitrogen, phosphorus, and sulfur) starvation or limitation. Other viable approaches such as light intensity, temperature, carbon dioxide, salinity stress, and metal influence can also achieve enhanced microalgal lipid production.fi=vertaisarvioitu|en=peerReviewed

Thermal Response of Multiple Pipes and Fluids Using COMSOL for Geothermal Energy System Application

A geothermal system is modeled using COMSOL. The purpose is to study and evaluate the thermal response of the pipes and the fluids. The model is designed for a low energy network. A part of this network is used to collect energy from a sediment layer under water body. This model depicts a heating system in the low energy shallow network which brings out the thermal response and helps implementing an efficient geothermal system application. This model executes in COMSOL on a special pipe dedicated as a heat collector for the heating system, to study the heat transfer within the pipes and the fluids used as a heat carrier. It also presents the thermal response of multiple fluids and compares the simulated and the measured data of the actual working fluid within the system. The temperature distribution and the heat flux along the length of the pipe are also taken into account in multiple pipes.©2014 NAUNfi=vertaisarvioitu|en=peerReviewed

Effects of sulphur on the storage stability of the bio and fossil fuel blends

In this study, the aim was to find out if mixing two common fuels together could be beneficial for both the environment and storage stability of fuel. It is obvious, that adding biodiesel to fossil fuel will decrease its sulphur content and reduce its carbon monoxide and hydrocarbon, sulphur dioxide and soot emissions. But will the high sulphur content enhance the storage stability of the biodiesel? Four B20 samples were produced, consisting of 20 vol% biodiesel and 80 vol% fossil diesel. The samples were prepared from rapeseed methyl ester (RME), low sulphuric fossil diesel fuel and high sulphuric diesel solvent. The blends had different sulphur contents of 6, 76, 149 and 226 mg kg-1. For these B20 fuel samples, the parameters were compared that correlate with the storage stability of the fuel blends. The studied parameters were the oxidation stability (OSI, according to EN 15751:2015), acid number (AN, according to EN 14104:2003) and kinematic viscosity (KV, by Stabinger SVM 3000 rotational viscometer). The measurements were carried out straight after mixing the blends, and again after 4, 8 and 12 weeks. According to the results, the fuel containing less sulphur slightly lost its oxidation stability within three months. Instead, the oxidation stability of high sulphuric samples improved within the same time frame. As a conclusion, the study gave a reason to assume that – in spite of its known drawbacks – the sulphur may be favourable to fuel blends’ storage stability but the phenomenon and chemistry should be studied in more detail.fi=vertaisarvioitu|en=peerReviewed

A questionnaire case study to investigate public awareness of smog pollution in China's rural areas

Smog pollution is one of China’s most pressing public health issues today and has therefore received significant attention worldwide. Not only cities but also villages in China are suffering from smog pollution, especially since 2013. However, there is limited information available about public awareness on smog pollution in China, especially for where it concerns the residents living in villages. Based on a questionnaire survey, this study aims to help fill this gap. The results of the study show that the income of the majority of respondents comes from working in the city, accounting for 31.6% of the total income. The percentages for respondents related to access to smog information from various channels are as follows: TV (28.5%), radio (24.2%), neighbors (13.5%), Internet (9.8%), newspapers (8.3%) and others (7.8%). As for attitudes regarding the severity degree and main cause of smog pollution, most respondents (33.7%) thought smog pollution in villages was somewhat severe, while 26.3% agreed that the main contributor to smog pollution was industrial emissions, followed by coal burning at power plants (20.9%) and vehicle emissions (17.7%). The results also indicate that most of the respondents were satisfied with the government’s performance in terms of smog control. However, 67.9% of respondents indicated they would remain silent and not intervene when confronted by an activity that causes smog pollution. This study can help to improve an understanding of public awareness regarding smog pollution in China’s rural areas and thereby activate positive public participation in smog pollution prevention and management in the search for sustainable development.fi=vertaisarvioitu|en=peerReviewed

Seabed Sediment as an Annually Renewable Heat Source

Thermal energy collected from the sediment layer under a water body has been suggested for use as a renewable heat source for a low energy network. A prototype system for using this sediment energy was installed in Suvilahti, Vaasa, in 2008 and is still in use. It provides a carbon-free heating and cooling solution as well as savings in energy costs for 42 houses. To be a real, renewable heat source, the thermal energy of the sediment layer needs to replenish annually. The goal of this paper is to verify the possible cooling or annual heat regeneration. The sediment temperatures were measured and analyzed in the years 2013–2015. The data were compared to the same period in 2008–2009. All measurements were taken in the same place. This paper also confirms the potential of the sediment heat, especially in the seabed sediment, using the temperature differences between the lowest and the highest values for the year. The results demonstrate that the collection of the heat energy does not cause permanent cooling of the sediment. This result was obtained by calculating the temperature difference between measurements in the warmest month and the month with the coldest temperatures. This indicates the extracted energy. The difference was found to be around 9.5 °C in 2008–2009, rising to around 11 °C for the years 2013–2014 and 2014–2015. This indicates the loaded energy. The energy utilization is sustainable: the sediment temperature has not permanently decreased despite the full use of the network for the heating and cooling of houses between 2008 and 2015.fi=vertaisarvioitu|en=peerReviewed

The effect of sulphur content on B20 fuel stability

The aim of this study was to investigate if a high amount of sulphur is favourable for the fuel blends' storage stability. The parameters that correlate with the storage stability of the fuel blends were compared with two B20 fuel samples consisting of 20 vol% biodiesel and 80 vol% fossil diesel. The studied parameters were the oxidation stability (OSI), acid number and kinematic viscosity. The measurements were carried out straight after mixing the blends, and again after 4 and 9 weeks. One of the B20 samples was prepared from rapeseed methyl ester (RME) and fossil diesel fuel containing 6.6 mg kg-1 sulphur and the other from the same RME but the fossil diesel fuel contained 186 mg kg-1 of sulphur. According to the results of this study, the fuel containing less sulphur had slightly better quality during the entire study. Though, the OSI of the fuel containing more sulphur decreased less in percentages than it did for the fuel containing less sulphur. As a conclusion, the study gives a reason to assume that the sulphur may be favourable to fuel blends’ storage stability but it should be studied for a longer time to confirm this statement.fi=vertaisarvioitu|en=peerReviewed

Kinematic viscosity studies for medium-speed CI engine fuel blends

Engine - driven power plants, run by diesel fuel or gas, will be needed for peaking power to keep the electricity grids stable when the production of renewable electricity, e.g. utilizing wind or solar power, is increased. The choice of the alternative, renewable fuels for engine - driven power plants and marine applications is at the moment quite narrow. The amount of renewables of all liquid fuels is at present less than 2%. Biodiesels, FAMEs, have been studied for long time and apparently, despite of the problems they may have, they are still in the great interest. One import ant increment to the category of alternatives is fuels that are produced from e.g. oil wastes, i.e., recycled fuels. They are not renewable, but recycling of potential energy raw materials is still one step forward in increasing the suitable and more susta inable options. To utilize the blends in medium - speed engines for power production, accurate knowledge of the physical and chemical properties of fuel blends is very important for the optimization of engine performance. The determination of the fuel kinema tic viscosity is needed to create proper fuel atomization. The injection viscosity affects directly the combustion efficiency and the engine power. Consequently, this study focused on measuring kinematic viscosity curves for seven fuel blends, as well as t he neat fuels used for blending. The temperature range was 10 – 90 °C. The fuels used for blending were rapeseed methyl ester, animal - fat based methyl ester, hydro - treated vegetable oil, light fuel oil and marine gas oil produced from recycled lubricating oi ls.fi=vertaisarvioitu|en=peerReviewed

Analysis of ground heat exchanger for a ground source heat pump : A study of an existing system to find optimal borehole length to enhance the coefficient of performance

Ground Source Heat Hump is one of the emerging technic to utilize the reservoir of geothermal energy in Europe. The crucial factor is to find the optimal length of the borehole to successfully design a heating system. The length of the borehole varies depending on the geographical area, the capacity of the heat pump and heat load of the desired building in consideration. Several methods have been theorized and validated using the experimental measurements to find the optimal length of the borehole. The most commonly used methods are American Society of Heating, Refrigeration and Air-conditioning Engineers and International Ground Source Heat Pump Association for sizing borehole heat exchanger. In this paper, an existing system is analyzed, for a 60 kilo Watts heat pump in an area of Finland with a ground source 250 meters of Borehole Heat Exchanger. Coefficient of Performance for current scenario is calculated, an optimal length is found for the heat capacity of the heat pump to enhance the performance of the system. Improved coefficient of performance is presented along with an easy method of finding the optimal length of the ground source.fi=vertaisarvioitu|en=peerReviewed