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Abstract In the context of the rural electrification challenge, sharing-based nanogrids represent an innovative approach for affordable and sustainable electricity. The peer-to-peer topology of these nanogrids is targeted at organic growth and thus requires real time monitoring and optimization. A data analysis tool has been developed, aiming at achieving an efficient power flow and real time optimization of generation, storage, load and distribution capacities. This paper elaborates the core algorithms of the network topology optimization and provides first results based on data from a pilot nanogrid in Bangladesh.

AbstractWorld-wide coal reserves can supply the global demand for primary energy for several centuries. However, low thickness and structural complexity may constrain the economic exploitation of many coal deposits. Taking into account these circumstances, underground coal gasification (UCG) can offer an economical and sustainable approach for coal exploitation and subsequent feedstock generation from the syngas. The UCG process produces a high-calorific synthesis gas mainly consisting of methane, hydrogen and carbon dioxide, which can be used for electricity generation or feedstock production at the surface. Considering the latter, the Urea process can be applied to establish the nitrogen based fertilizer carbamide (CH4N2O). The required feedstock for carbamide production in the Urea process can be supplied by UCG syngas. The aim of the present study was the development of an integrated carbon utilisation concept based on the coupled UCG-Urea process. A significant amount of carbon dioxide from the UCG synthesis gas is required for carbamide production in the Urea process, while the excessive carbon dioxide can be re-injected into the cavities resulting in the coal seams and surrounding strata after the gasification process. Thus, a new approach for utilisation of carbon dioxide resulting from coal combustion was developed to provide a coupled technology also comprising geological storage of excessive carbon dioxide. A theoretical feasibility study considering UCG-Urea process economics and potentials of UCG and carbon dioxide storage in the gasified strata was conducted for a selected study area in northern Bangladesh revealing the high competitiveness of the combined technology on the international feedstock markets.

AbstractThe CO2-neutral self-supply of heat and electric energy is an important objective for new and existing buildings in the future [1,2]. Therefor the energy autonomous house (EAH) as a new concept for single-family buildings in central Europe is presented. It represents a further development of the solar and efficiency house concepts based on full self-sufficiency in thermal (partly provided by a fireplace) and electrical energy (100%). Two occupied houses have been built in Germany and they are under an extensive scientific monitoring with real user behavior since 2014. This contribution is focused on thermal energy balances and the differences due to different user behavior and the influence of weather conditions. The evaluated solar fraction was fsol, th ≥ 71.4% and fsol, el ≥ 91.8% for both houses in 2014. So far the 100% autonomy in electricity could not be reached due to the unusual low irradiation in Jan. and Dec. 2014 (-24% / -37% compared to long term values). Nevertheless the planned low electricity consumption of ∼ 2000 kWh/year could nearly be achieved, whereby a self-consumption rate of electric energy gains of ≥ 31.8% were assumed. Further findings of 1 ½ years of monitoring of the two EAH are presented within the paper.

Abstract This study aims at determining the technology combination that provides the lowest emissions and energy cost for the food-industrial sector. Using a linear optimization objective function in determining the least-cost pathway, data from various sources were compiled to perform simulations on two scenarios; a business as usual (BAU) case and an 80% greenhouse gas (GHG) emissions reduction. Even in the base case, the emission level reaches 21% of 1990 levels; a reduction of 39% over the simulation period. This indicates that even without the imposition of GHG constraints on the food sector, it is economically more beneficial for the industry to migrate from fossil fuels. This migration takes place by replacing energy from LPG, LFO, Kerosene, HFO, Coal and Natural gas with biomass, biogas and CHP electricity. Economic benefits arise from the fact that biogas and biomass are produced from wastes which are generated onsite within food factories, hence the avoidance of purchasing energy feedstock from the market. The change in energy consumption between the two scenarios is similar due to the prevalence of least-cost solutions and similar energy and food demand requirements. However, the reduction in emissions are greater in the 80%-GHG case than the BAU case; 52% compared to 39% for the BAU case, for 2050 relative to 2010. This is largely owing to decarbonization of grid electricity. This study finds that the food-industrial sector has the potential to exceed this 80% reduction target to a value of 92%, due to the availability of onsite feedstocks to generate biogas. In this simulation, of all waste produced, 92% of waste feedstock is consumed in AD and CHPs, whilst the remaining 8% is dried and processed to be burned in biomass boilers.

AbstractConventional solar compound parabolic concentrators are fitted with one tubular receiver situated along the axis of the two parabolas. This work investigates the potential of using two tubular receivers in one compound parabolic concentrator. Using advanced ray tracing technique, the optical efficiency of a compound parabolic concentrator with two tubular receivers aligned horizontally and vertically was predicted. Results show that the horizontal configuration outperforms both the single and the vertical configurations by up to 15%. Horizontally aligned elliptical single tube was also investigated and results showed an increase in the average daily optical efficiency compared to the single tube configuration by 17%. This work highlights the potential of using either two tubular receivers or single elliptical one aligned horizontally in one concentrator to improve the optical efficiency.

AbstractWe measured dissolved inorganic carbon (DIC) stable isotopes (813CDIC in ‰) of brine from an observation well within the first aquifer above the CO2 reservoir at the Ketzin pilot site, to test weather these can detect potential CO2 leakage. The monitoring revealed that DIC concentrations and 813CDIC values were masked by the used high alkaline drilling mud, even eight months after well development. However, subsequent changes in 813CDIC and DIC from of -27 ‰ and 165mg L−1 to -23.5 ‰ and 116mg L−1 reflect most likely a shift towards pristine values of the aquifer.

AbstractAs a developing industry, CCS in the UK can be modeled as a technical innovation system (TIS) which will likely develop in a highly non-linear fashion, relying on feedbacks from a range of system functions including R&D, market creation and learning-by-doing.Following similar work in other nations the TIS is analysed by an expert questionnaire and in-depth systems analysis. The results include input from 34 CCS experts from all areas of the TIS and allow potential weaknesses that may hamper development to be identified. An update on system functions since the survey is also then included to gauge recent developments.