• Energy Research
• 7. Clean energy close
• NL close

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.

Abstract A comprehensive numerical model for selective low-pressure chemical vapor deposition (LPCVD) of tungsten from hydrogen and WF 6 in a single-wafer reactor has been developed. The computational fluid dynamics (CFD) code PHOENICS-CVD is used for transient solutions of the two-dimensional transport equations of heat, momentum and chemical species in the reactor. A detailed model is used for the kinetics of tungsten deposition at the surface. A model for the nucleation of intermediates, which are formed at the surfaces where tungsten is deposited and are transported through the gas phase, is used to describe the loss of selectivity. This opens the way for qualitative study of the influence of process conditions and reactor configurations on the selectivity of this process. The selectivity is found to improve at high flow rates, low total pressures and low partial pressures of WF 6 .

The application of Next Generation Growing (NGG, in Dutch “Het Nieuwe Telen”) in Dutch greenhouses has resulted in energy savings, accompanied by the extensive use of screens. The latter has affected the control of greenhouse climate which strongly depends on the air and humidity exchange between the top and bottom greenhouse compartment, as they are separated by the screen itself. When the screens are fully deployed an air exchange/mix system (VentilationJet) that blows dry and cold air from the top compartment into the greenhouse can be used to lower the greenhouse air temperature and relative humidity in a controllable way. The effect of this greenhouse climate control equipment use on vertical air temperature profile as well as on energy use was studied in a commercial greenhouse. Effects of artificial lighting, heating with pipes below the crop, activation of vertical fans and air exchange rate were analyzed during the winter of 2018. It was observed that when significant heat input (radiation) at the top of the crop occurred a vertical temperature gradient up to 2°C exists, with the bottom of the crop being colder than the top. This temperature gradient cannot be reduced by using only vertical air circulation fans but it can be minimized by additional heat input at the bottom; this may result in excess heat that has to be removed through either natural ventilation or with the use of VentilationJet when the screens are deployed. During the studied period about a quarter of the daily gas use for heating took place at the same time as the VentilationJet was removing warm and humid air from the top of the greenhouse.

Artículos en revistas Numerical models of transmission-constrained electricity markets are used to inform regulatory decisions. How robust are their results? Three research groups used the same data set for the northwest Europe power market as input for their models. Under competitive conditions, the results coincide, but in the Cournot case, the predicted prices differed significantly. The Cournot equilibria are highly sensitive to assumptions about market design (whether timing of generation and transmission decisions is sequential or integrated) and expectations of generators regarding how their decisions affect transmission prices and fringe generation. These sensitivities are qualitatively similar to those predicted by a simple two-node model. info:eu-repo/semantics/publishedVersion

In the face of the rapidly dwindling carbon budgets, negative emission technologies are widely suggested as required to stabilize the Earth’s climate. However, finding cost-effective, socially acceptable, and politically achievable means to enable such technologies remains a challenge. We propose solutions based on negative emission technologies to facilitate wealth creation for the stakeholders while helping to mitigate climate change. This paper comes up with suggestions and guidelines on significantly increasing carbon sequestration in coffee farms. A coffee and jackfruit agroforestry-based case study is presented along with an array of technical interventions, having a special focus on bioenergy and biochar, potentially leading to “negative emissions at negative cost.” The strategies for integrating food production with soil and water management, fuel production, adoption of renewable energy systems and timber management are outlined. The emphasis is on combining biological and engineering sciences to devise a practically viable niche that is easy to adopt, adapt and scale up for the communities and regions to achieve net negative emissions. The concerns expressed in the recent literature on the implementation of emission reduction and negative emission technologies are briefly presented. The novel opportunities to alleviate these concerns arising from our proposed interventions are then pointed out. Our analysis indicates that 1 ha coffee jackfruit-based agroforestry can additionally sequester around 10 tonnes of CO2-eq and lead to an income enhancement of up to 3,000–4,000 Euros in comparison to unshaded coffee. Finally, the global outlook for an easily adoptable nature-based approach is presented, suggesting an opportunity to implement revenue-generating negative emission technologies on a gigatonne scale. We anticipate that our approach presented in the paper results in increased attention to the development of practically viable science and technology-based interventions in order to support the speeding up of climate change mitigation efforts.

This paper addresses the application of direct drive machines in wave energy conversion, with special focus on the AWS full scale prototype tested offshore Portugal in 2004. A short introduction to wave energy is given, describing its features as a renewable resource, the principles and the challenges behind its capture and conversion. The AWS wave energy conversion concept is described, as well it's full scale prototype design process, construction and installation. Furthermore, experimental results from offshore tests are presented.

Abstract Multinary Cu(In,Ga)(Se,S) 2 absorbers (abrev. CIGSSe) are promising candidates for reducing the cost of photovoltaics well below the cost of crystalline silicon. Shell Solar has pioneered production of this new thin film technology and is now with the first generation at a volume of well over 1 MW/year. In a separate pilot line for second generation products we have further improved the performance of CIGSSE based solar modules. We developed a novel CIGSSE formation technique called stacked elemental layer rapid thermal processing (SEL-RTP). This process has recently been scaled up from initial laboratory sized mini-modules (10 × 10 cm 2 ) to full sized power modules of 60 × 90 cm 2 . The present paper concentrates on in situ and ex situ characterization techniques that were developed to control and further improve large area CIGSSE processing. The crystalline thin film formation process has been analyzed with in situ thin film calorimetry and in situ X-ray diffraction (XRD). That work has added fundamental insights and accelerates the optimization process. The depth distribution of gallium and sulfur has been determined by secondary ion mass spectroscopy (SIMS) for different selenization and sulfurization processes. Appropriate profiles of these elements allow for a deliberate bandgap profiling within the Cu(In,Ga)(S,Se) 2 absorber. In addition further quality control tools like X-ray fluorescence analysis and Raman spectroscopy for stoichiometry monitoring, photoluminescence lifetime mapping and thermographic imaging have been developed in order to improve large area uniformity and reproducibility. Some first full sized modules from the new pilot line look very promising: Aperture area efficiencies of up to 13.1% for monolithic thin film circuits on 0.54 m 2 and a module power of 65 W represent an international champion value for large are thin film solar modules.