Vesien tila hyväksi yhdessä : Tornionjoen vesienhoitoalueen vesienhoitosuunnitelma vuosiksi 2016-2012

Tähän vesienhoitosuunnitelmaan on koottu tiedot vesien tilasta sekä vesienhoitokaudella 2016–2021 tarvittavat toimenpiteet vesien tilan parantamiseksi ja ylläpitämiseksi Tornionjoen vesienhoitoalueella. Suunnitelma kattaa Suomalais-ruotsalaisen vesienhoitoalueen Suomen puoleisen alueen. Toimenpiteillä vähennetään rehevöitymistä ja vesiympäristölle vaarallisten ja haitallisten aineiden esiintymistä sekä vesistöjen rakenteessa ja hydrologiassa tapahtuneiden muutosten vaikutuksia. Vesienoitoalueen vesien tilaan on vaikuttanut niin haja- ja pistekuormitus kuin maa- ja vesiympäristön fyysinen muokkaaminen. Vesistöjä muuttavat tekijät painottuvat vesienhoitoalueen eteläosaan. Eniten vesistöjen tilaa ovat muuttaneet uittoperkaukset sekä suo- ja metsäojitukset. Tengeliönjoen vesistössä vesistöjen säännöstely ja rakentaminen ovat muuttaneet vesien tilaa. Alueen ihmistoiminnasta sisävesiin tulevasta ravinnekuormituksesta huomattava osuus tulee hajakuormituksena maa- ja metsätaloudesta sekä hajaasutuksesta. Pistemäinen ravinnekuormitus on pääosin peräisin teollisuudesta ja yhdyskuntien jätevesistä. Teollisuuden ja taajamien jätevesien puhdistukseen on panostettu viime vuosikymmeninä voimakkaasti ja pistekuormitus ei ole nykyisellään erityisen suuri vesiensuojelullinen ongelma. Kaivosteollisuus vesienhoitoalueella on mahdollisesti kasvussa, mikä lisää vesistöjen pilaantumisriskiä etenkin metallien ja vesille haitallisten aineiden osalta. Osalla pohjavesialueista kuormittava toiminta, kuten pilaantuneet maa-alueet, maa-ainesten otto, asutus, teollinen toiminta, polttoaineiden ja kemikaalien varastointi, liikenne ja kuljetukset voivat aiheuttaa vaaraa pohjavesien hyvälle laadulle. Vesienhoitoalueen vesistöt purkautuvat Perämereen, joka on kuormitukselle herkkä murtovesialue. Valtaosa sen ravinne- ja kiintoainekuormituksesta tulee jokivesien mukana, joten kuormituksen vähentäminen valuma-alueilla parantaa myös rannikkovesien tilaa. Rannikkovesiin kohdistuu myös suoraa kuormitusta teollisuuslaitoksista ja yhdyskuntien jätevedenpuhdistamoista. Rannikkovesien tilan parantaminen kytkeytyy merenhoidon suunnitteluun.

Dynamic model development of adiabatic compressed air energy storage

The share of variable renewable energy in electricity generation has seen exponential growth during the recent decades, and due to the heightened pursuit of environmental targets, the trend is to continue with increased pace. The two most important resources, wind and insolation both bear the burden of intermittency, creating a need for regulation and posing a threat to grid stability. One possibility to deal with the imbalance between demand and generation is to store electricity temporarily, which was addressed in this thesis by implementing a dynamic model of adiabatic compressed air energy storage (CAES) with Apros dynamic simulation software. Based on literature review, the existing models due to their simplifications were found insufficient for studying transient situations, and despite of its importance, the investigation of part load operation has not yet been possible with satisfactory precision. As a key result of the thesis, the cycle efficiency at design point was simulated to be 58.7%, which correlated well with literature information, and was validated through analytical calculations. The performance at part load was validated against models shown in literature, showing good correlation. By introducing wind resource and electricity demand data to the model, grid operation of CAES was studied. In order to enable the dynamic operation, start-up and shutdown sequences were approximated in dynamic environment, as far as is known, the first time, and a user component for compressor variable guide vanes (VGV) was implemented. Even in the current state, the modularly designed model offers a framework for numerous studies. The validity of the model is limited by the accuracy of VGV correlations at part load, and in addition the implementation of heat losses to the thermal energy storage is necessary to enable longer simulations. More extended use of forecasts is one of the important targets of development, if the system operation is to be optimised in future.

Liquid-phase alcohol promoted methanol synthesis from CO2 and H2

Methanol is an important and versatile compound with various uses as a fuel and a feedstock chemical. Methanol is also a potential chemical energy carrier. Due to the fluctuating nature of renewable energy sources such as wind or solar, storage of energy is required to balance the varying supply and demand. Excess electrical energy generated at peak periods can be stored by using the energy in the production of chemical compounds. The conventional industrial production of methanol is based on the gas-phase synthesis from synthesis gas generated from fossil sources, primarily natural gas. Methanol can also be produced by hydrogenation of CO2. The production of methanol from CO2 captured from emission sources or even directly from the atmosphere would allow sustainable production based on a nearly limitless carbon source, while helping to reduce the increasing CO2 concentration in the atmosphere. Hydrogen for synthesis can be produced by electrolysis of water utilizing renewable electricity. A new liquid-phase methanol synthesis process has been proposed. In this process, a conventional methanol synthesis catalyst is mixed in suspension with a liquid alcohol solvent. The alcohol acts as a catalytic solvent by enabling a new reaction route, potentially allowing the synthesis of methanol at lower temperatures and pressures compared to conventional processes. For this thesis, the alcohol promoted liquid phase methanol synthesis process was tested at laboratory scale. Batch and semibatch reaction experiments were performed in an autoclave reactor, using a conventional Cu/ZnO catalyst and ethanol and 2-butanol as the alcoholic solvents. Experiments were performed at the pressure range of 30-60 bar and at temperatures of 160-200 °C. The productivity of methanol was found to increase with increasing pressure and temperature. In the studied process conditions a maximum volumetric productivity of 1.9 g of methanol per liter of solvent per hour was obtained, while the maximum catalyst specific productivity was found to be 40.2 g of methanol per kg of catalyst per hour. The productivity values are low compared to both industrial synthesis and to gas-phase synthesis from CO2. However, the reaction temperatures and pressures employed were lower compared to gas-phase processes. While the productivity is not high enough for large-scale industrial operation, the milder reaction conditions and simple operation could prove useful for small-scale operations. Finally, a preliminary design for an alcohol promoted, liquid-phase methanol synthesis process was created using the data obtained from the experiments. The demonstration scale process was scaled to an electrolyzer unit producing 1 Nm3 of hydrogen per hour. This Master’s thesis is closely connected to LUT REFLEX-platform.