• Energy Research
• Closed Access close
• Embargo close
• 13. Climate action close
• 11. Sustainability close
• 6. Clean water close
• 15. Life on land close
• NL close

Space travel, often used by the authors as an equivalent to ‘space tourism’, and outer-space migration should become part of the sustainability discourse – that is the most tempting argument of the...

Psychrophilic anaerobic treatment is an attractive option for wastewaters that are discharged at moderate to low temperature. The expanded granular sludge bed (EGSB) reactor has been shown to be a feasible system for anaerobic treatment of mainly soluble and pre-acidified wastewater at temperatures of 5--10 degrees C. An organic loading rate (OLR) of 10--12 kg chemical oxygen demand (COD) per cubic meter reactor per day can be achieved at 10--12 degrees C with a removal efficiency of 90%. Further improvement might be obtained by a two-module system in series. Stabile methanogenesis was observed at temperatures as low as 4--5 degrees C. The specific activity of the mesophilic granular sludge was improved under psychrophilic conditions, which indicates that there was growth and enrichment of methanogens and acetogens in the anaerobic system. Anaerobic sewage treatment is a real challenge in moderate climates because sewage belongs to the 'complex' wastewater category and contains a high fraction of particulate COD. A two-step system consisting of either an anaerobic up-flow sludge bed (UASB) reactor combined with an EGSB reactor or an anaerobic filter (AF) combined with an anaerobic hybrid reactor (AH) is successful for anaerobic treatment of sewage at 13 degrees C with a total COD removal efficiency of 50% and 70%, respectively.

Abstract Climate change is a major challenge for the energy sector, particularly for wind energy onshore and offshore. Climate models are the only tool which is able to produce physical-based projections of future changes in response to increasing greenhouse gas emissions. In the present study, the Western Iberian offshore wind resource is analysed for present and future climates, using a set of regional climate models (RCMs) simulations produced in the framework of the CORDEX experiment at 0.11° resolution (∼12 km), and a regional climate simulation produced with the WRF model at higher resolution (9 km). All these simulations are firstly, evaluated against wind buoy measurements and Cross-Calibrated Multi-Platform (CCMP) wind data, and used to generate two high quality multi-model ensembles based on the individual model’s performance. The results of the WRF simulation and of the two multi-model ensembles are then used to describe the wind resource both for the present and future climates, according to the RCP4.5 and RCP8.5 emission scenarios. This allows the assessment of the climate change signal on the offshore wind and to provide an uncertainty measure of these projections. The vast majority of climate models project reductions of wind speed and wind power for all seasons, with the exception of summer. For the RCP8.5 emission scenario the multi-model ensembles project reductions in power density of around 7% for winter, 4% for spring and 12% for autumn, and increases of 5% for summer. In the latter, and increase up to 20% in power density is forecasted for the Iberian northwest coast. This is sufficient to offset the yearly balance, in as much as no change is expected at a yearly scale for this area. For the remaining west Iberian coast, a yearly reduction of less than 5% is estimated. These results are shared by the two multi-model ensembles and by WRF higher resolution simulation (9 km). The projected changes have the consequence of reducing the annual cycle of power density availability and of its yearly mean values. Finally, for the less aggressive scenario, RCP4.5, the changes have the same signal but with smaller values.

Global emission inventories with 1°x 1°resolution were compiled for nitrogen oxides (NO + NO2, together denoted as NO(x)), ammonia (NH3) and nitrous oxide (N2O) emissions. For NO(x) the estimated global anthropogenic emission for 1990 is about 31 million ton N year-1. The major anthropogenic sources identified include fossil fuel combustion (70%, of which the major sources are road transport and power plants) and biomass burning (20%). Natural sources contribute about 19 million ton N year-1, mainly lightning and soil processes. For NH3the estimated global emission for 1990 is about 54 million ton N year-1. The major sources identified include excreta from domestic animals and wild animals, use of synthetic N fertilisers, oceans and biomass burning. About half of the global emission comes from Asia, and about 70% is related to food production. For N2O the major sources considered include fertilised arable land, animal excreta, soils under natural vegetation, oceans, and biomass burning. The global source of N2O is about 15 million ton N2O-N year-1of which about 30% is related to food production. All three inventories are available on a sectoral basis on a 1°x 1°grid for input to global atmospheric models and on a regional/country basis for policy analysis.

This aim of this special section is to present applications of electrical energy storage. The issue summarizes the most recent research and development and it identifies issues that must be addressed for the successful application of storage technologies. We were extremely impressed by the number of papers submitted in response to the call for papers and the spectrum of interests that the international community has for energy storage. The papers solicited discuss a broad range of environmental, economic, technical, market, and policy considerations associated with the application of energy storage on power systems. Out of 83 submissions, we were able to accept 22 exceptional contributions. The final paper selection was made based on the quality of the papers and an attempt to balance a broad topical representation. The final papers were divided into five topical areas as follows: 1) Hybrid Storage Management System and its Applications in Microgrids; 2) Storage for Active Distribution Networks; 3) Energy Storage for Provision of Ancillary Services; 4) Energy Storage for Integration of Renewable Resources; and 5) Operation of Energy Storage for Reliability.

Abstract The state of the art of hydrolysis-fermentation technologies to produce ethanol from lignocellulosic biomass, as well as developing technologies, is evaluated. Promising conversion concepts for the short-, middle- and long-term are defined. Their technical performance was analysed, and results were used for economic evaluations. The current available technology, which is based on dilute acid hydrolysis, has about 35% efficiency (HHV) from biomass to ethanol. The overall efficiency, with electricity co-produced from the not fermentable lignin, is about 60%. Improvements in pre-treatment and advances in biotechnology, especially through process combinations can bring the ethanol efficiency to 48% and the overall process efficiency to 68%. We estimate current investment costs at 2.1 k€/kW HHV (at 400 MW HHV input, i.e. a nominal 2000 tonne dry/day input). A future technology in a 5 times larger plant (2 GW HHV ) could have investments of 900 k€/kW HHV . A combined effect of higher hydrolysis-fermentation efficiency, lower specific capital investments, increase of scale and cheaper biomass feedstock costs (from 3 to 2 €/GJ HHV ), could bring the ethanol production costs from 22 €/GJ HHV in the next 5 years, to 13 €/GJ over the 10–15 year time scale, and down to 8.7 €/GJ in 20 or more years.

The large thermal potentials with geothermal gradient of abandoned wells provide the possibility and opportunity for carbon-neutrality transition of district heating systems, whereas energy harvesting from abandoned geothermal wells is full of challenges, due to the considerable initial investment in economic cost, system performance degradation, and so on. In this chapter, a systematic and comprehensive review on the application techniques of abandoned wells is presented, in terms of advanced thermal/power conversions, renewable integrations for district heating, and strategies for performance enhancement. Discussions on real applications have been conducted and future prospects presented, from perspectives of lifetime system performance, techno-economic feasibility analysis, and potential assessment of abandoned wells for carbon-neutrality transition. The results of this chapter can provide preliminary knowledge and cutting-edge technologies on renewable integrations with abandoned wells, so as to demonstrate techno-economic-environmental potentials of abandoned wells and contributions toward carbon-neutrality transition. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Design & Construction Management

Increasing energy efficiency is discussed as an effective way to protect the climate, even though this is frequently associated with additional (investment) costs when compared to standard technologies. However, the investment costs of emerging energy-efficient technologies can be reduced by economies of scale and experience curve effects. This also brings about higher market penetration by lowering market barriers. Experience curves have already been analyzed in detail for renewable energy technologies, but are not as well documented for energy-efficient technologies despite their significance for energy and climate policy decisions. This work provides empirical evidence for effects of economies of scale and experience on the costs of energy-efficient electric motors. We apply a new methodology to the estimation of learning effects that is particularly promising for energy-efficient technologies where the very low data availability did not allow calculations of learning rates so far. Energy-efficient electric motors are a highly relevant energy technology that is responsible for about 55% of German electricity consumption. The analysis consists of three main steps. First, the calculation of composite price indices based on gross value added statistics for Germany which show the changes in cost components of electric motors over the period 1995 to 2006; second, an estimation of the corresponding learning rate which is, in a third step, compared with learning rates observed for other energy-efficient technologies in a literature review. Due to restrictions of data availability, it was not possible to calculate a learning rate for the differential costs of energy-efficient motors compared to standard motors. Still, we estimated a learning rate of 9% for “Eff2” motors in a period when they penetrated the market and replaced the less efficient “Eff3” motors. Furthermore, we showed the contribution of different effects to these cost reductions, like a reduction of material use per motor produced by 15% and an improvement of labor productivity of 43%.