The ambitious CO2 emission reduction targets for the transport sector set in the Paris Climate Agreement require low-carbon energy solutions that can be commissioned rapidly. The production of gasoline, kerosene, and diesel from renewable methanol using methanol-to-olefins (MTO) and Mobil’s Olefins to Gasoline and Distillate (MOGD) syntheses was investigated in this study via process simulation and economic analysis. The current work presents a process simulation model comprising liquid fuel production and heat integration. According to the economic analysis, the total cost of production was found to be 3409 €/tfuels (273 €/MWhLHV), corresponding to a renewable methanol price of 963 €/t (174 €/MWhLHV). The calculated fuel price is considerably higher than the current cost of fossil fuels and biofuel blending components. The price of renewable methanol, which is largely dictated by the cost of electrolytic hydrogen and renewable electricity, was found to be the most significant factor affecting the profitability of the MTO-MOGD plant. To reduce the price of renewable fuels and make them economically viable, it is recommended that the EU’s sustainable transport policies are enacted to allow flexible and practical solutions to reduce transport-related emissions within the member states.
A traditional sand filter for treatment of household wastewater was constructed in the fall of 2012 at Biolinja 12, Turku, Finland. Construction work was led and monitored by an authorized wastewater treatment consultant. The filter was placed on a field bordered by open ditches from all sides in order to collect excess rain and snowmelt waters. The filter was constructed and insulated from the environment so that all outflowing water was accounted for. Untreated, mainly municipal, wastewater from Varissuo suburb was pumped from a sewer separately via three septic tanks (volume = 1 m3 each) into the filters. Normally, wastewater was distributed to ground filters automatically according to pre-programmed schedule. Initially, the daily flow was 1200 L day−1 to reflect the average organic load of a household of five persons (load: ca 237 g day−1 BOD; 73 g day−1 total N; and 10.4 g day−1 total P). Later in the test, the flow rate was decreased first to 900 and then to 600 L day−1 to better reflect the average volume produced by five persons. Volumes of inlet wastewater as well as treated water were monitored by magnetic flow meters. Samples were withdrawn from the inlet water, from the water entering the filters after the third septic tank, and from the outflowing water. After an initial adaption time, the reductions in BOD and chemical oxygen demand were constantly between 92 and 98%, showing that the biological degradation process in the filters functioned optimally and clearly comply with the national and EU standards. The reduction in total nitrogen and total phosphorus, however, reached required levels only during the first months of testing, apparently when buildup of microbial biomass was still ongoing. After this initial period of 3 months showing satisfactory reduction levels, the reduction of total nitrogen varied between 5 and 25% and total phosphorus mostly between 50 and 65%. Nitrification was efficient in the filter, but as indicated by high nitrate levels and poor nitrogen reductions, denitrification was inefficient or absent. During the winter period, the temperature in the filter dropped to near freezing, but at all time points, the flow of water was unaffected by freezing. During snowmelt and heavy rain, occasional flooding was observed. Such situations may lead to dilution rather than purification of the wastewater. In conclusion, the sand filter tested worked well for reduction of the organic load in municipal wastewater but failed to sufficiently reduce nitrogen and phosphorus levels.
Buildings and construction are responsible for about 40% of the energy and process-related CO2 emissions worldwide. At present, the renewal rate of building stock is relatively low, for example in Finland, which is the case under study in this work, it is 1.5% per year. With respect to the target of a carbon neutral world by 2050, the effect on emissions of existing building stock must be considered. In this paper, we present the results of analysis of energy efficiency improvement investment in 12 city-owned buildings in two Finnish cities. Using measured heat and electrical energy consumption data, a model was developed for analyzing the impact of active and passive energy efficiency improvement investment options per building. The examined active technologies were heat pumps, solar photovoltaic panels, and heat recovery in ventilation system, and the passive improvement compared was structural improvements in the building envelope. The results show that investments in energy efficiency improvements can reduce the yearly energy-related operating costs of the buildings by 35% on average. The study further finds that usually investment in active energy efficiency improvements provides a bigger return on investment than passive improvements. The profitability of examined measures makes Public–Private Partnership a feasible way to provide funding for renovation of public buildings.Graphical abstract
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