• Energy Research
• physical sciences close
• 13. Climate action close
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AbstractEnergy is the biggest crisis to humanity in the future. Nowadays, most of the energy used on earth comes from oil, gas and coal. According to the recent exploring and consuming rates, the energy will be exhausted in 50-100 years. Whether we can solve the crisis is closely related to the survival of humanity on the earth. The irradiation from the sun is the biggest energy source. Building PV power plant to utilize the energy from sun will be an only way to sustain the life cycle on the earth. However, the development of PV power plants require the huge supply of PV cell and the fabrication process may bring a quantity of pollution and waste, which is harmful to the environment. On the other hand, super large PV power plant will occupy huge land. If the land cannot be explored and used reasonably, this will not benefit the human life either. In this article, we address the discussions about the above problems and propose the initial suggestions about development trend of PV industry and the safety operation mode of super PV power plant.

AbstractUsing a low supply water temperature in heating conditions and a high water temperature during cooling can increase energy efficiency, use renewable energy sources, and provide a comfortable and healthy indoor climate. High temperature cooling and low temperature heating is achieved by reducing temperature difference in heat trans er and energy transportation process. The losses in temperature difference can be classified into three types: by heat/moisture exchange; by energy transportation through air/water circulation; by indoor terminal that releases heat/cooling to indoor condit oned space. The air handling process of HVAC system and indoor terminals are the key factor of reducing temperature differen e.Aiming at the losses in HVAC system, Annex 59, titled High Temperature Cooling & Low Temperature Heating in Buildings, is a new international cooperative work under the framework of International Energy Agency (IEA) Energy in Buildings and Communities (EBC). This paper introduc s the background, scope, objective, structure and deliverables of Annex 59. Annex 59 will try to present a new perspective and a new concept to analyze HVAC system in buildings. The goal of the Annex is to build up new concept of analyzing HVAC system from the perspective of reducing mixture loss and transfer loss and th n apply it in high temperature cooling and low temperature heating system.

Accurate estimation of extreme wave conditions is critical for offshore renewable energy activities and applications. Wave power is the transport of energy by wind waves, and the capture of that energy to do useful work. Wave energy converter (WEC) devices are designed to sustain the wave-induced loads that they experience during both operational and survival sea states. The extreme values of these forces are often a key cost driver for WEC designs. These extreme loads often occur during severe storms; therefore careful examination of harsh wave conditions during the device design process is needed. Consequently the development of a specific extreme condition modeling method is essential. This paper presents a novel method for estimating extreme wave statistics, based on the hourly measured wave height maxima at the location of interest. Wave measurements, analyzed in this paper, were collected at SEM-REV offshore sea station located near the coast of France, during years 2001–2010. Note that applied statistical methodology is general and can be well applied to a measured WEC response, and its technology risk assessment. Accurate estimation of extreme wave conditions is critical for offshore renewable energy activities and applications. SEM-REV is known French wave energy test site. The method, referred to as ACER method, is presented in brief detail. ACER method provides an accurate extreme value prediction, utilizing available data efficiently. In this study the estimated return level values, obtained by ACER method, are compared to the corresponding return level values obtained by Gumbel method. Based on the overall performance of the proposed method, it is concluded that the ACER method can provide a robust and accurate prediction of extreme wave height at a given location.

Diesel engine exhaust pipes are in a high-temperature and high-oxygen environment; the carbon soot formed by fuel combustion will be partially oxidized, and its physicochemical properties will change significantly after oxidation. In order to study the effect law of partial oxidation on carbon soot particles emitted from automobiles, commercial carbon black samples (Printex-U carbon) were selected to replace actual carbon soot particles in this paper, and experiments were conducted on a fixed-bed catalytic oxidation device to obtain carbon soot particles with four oxidation rates by varying the time duration of oxygen introduction. Subsequently, the microstructure images of the corresponding carbon soot particles were obtained using TEM and measured after image processing with ImageJ software. The results showed that the average particle size, particle layer spacing, and distortion of carbon soot particles gradually decreased with the increase in oxidation rate. Moreover, the basic particle edge structure of carbon soot particles gradually blurred, the disordered structure inside the carbon soot particles increased, and the structure was destroyed or oxidized away with the gradual oxidation of the outer layer. Lastly, the density degree inside the particles gradually increased, the outer carbon layer arrangement became more regular, and the graphitization degree gradually became larger. The oxidation of carbon soot particles followed the contraction model and the internal oxidation model.

Abstract The Serpens Molecular Cloud is one of the most active star-forming regions within 500 pc, with over 1000 young stellar objects (YSOs) at different evolutionary stages. The ages of the member stars inform us about the star formation history of the cloud. In this paper, we develop a spectral energy distribution (SED) fitting method for nearby evolved (diskless) young stars from members of the Pleiades to estimate their ages, with a temperature scale adopted from APOGEE spectra. When compared with literature temperatures of selected YSOs in Orion, the SED fits to cool (<5000 K) stars have temperatures that differ by an average of ≲50 K and have a scatter of ∼210 K for both disk-hosting and diskless stars. We then apply this method to YSOs in the Serpens Molecular Cloud to estimate ages of optical members previously identified from Gaia DR2 astrometry data. The optical members in Serpens are concentrated in different subgroups with ages from ∼4 to ∼22 Myr; the youngest clusters, W40 and Serpens South, are dusty regions that lack enough optical members to be included in this analysis. These ages establish that the Serpens Molecular Cloud has been forming stars for much longer than has been inferred from infrared surveys.

AbstractAn automatic pump is developed using low water‐head hydropower. The energy conversion efficiency η of the gas‐water energy conversion equipment is the focus. In this equipment, low‐head water normally drains to the vertical downcomer. When water particles separate via gravity, a vacuum is generated, and air is mixed into the water spontaneously. High‐pressure gas is ultimately produced at the end of the pipe. To discuss the effects of the air intake pipe diameter, river drop and water flow rate on η, a full‐scale experiment is conducted, and an analytical solution based on the separation of water particles is derived. The air intake pipe diameter has almost no effect on η, but η changes dramatically as the water flow rate varies. Meanwhile, η initially increases and then decreases as the river drop increases. These findings enable the development of a method for low water‐head hydropower utilization.

Plutonium mononitride is one of the main fuels for Generation IV reactors and can be prepared from nitrogenation of plutonium hydride. We investigated the adsorption and dissociation of nitrogen on PuH2 (111) surface to elaborate the initial stage of nitrogenation. The adsorption energies varied greatly with respect to the adsorption sites and orientations of the adsorbed molecule. The nitrogen exhibited preferential adsorption above the ccp site, where the molecular nitrogen was nearly parallel to the PuH2 surface and pointed to the nearest Pu atom. The orbital hybridization and the electrostatic attraction between the Pu and N weakened the N-N bond in the adsorbed molecule. The mechanism of the dissociation process was investigated within transition state theory, and the analysis of the activation barrier indicated that dissociation of nitrogen is not the rate-determining step of nitrogenation. These findings can contribute to a better understanding of the nuclear fuel cycle.

Abstract With the plan to increase nuclear generating capacity to 58 GWe and more than 30GWe under construction by 2020, China would have to confront the challenge from the transportation safety of nuclear material. In this paper, based on the analysis of transportation systems and the accident scenarios, the safety evaluation index system of spent fuel road transportation was established by using analytic hierarchy process (AHP), and the transportation safety evaluation model was constructed by weighted nearest neighbor method. By using the model, the safety evaluation of spent fuel road transportation in DaYa Bay nuclear power plant was carried out. The evaluation results showed that the whole transportation was safe, though it has safety risk caused by the weather and the junctions of the bridges and tunnels. In addition, the results from the fuzzy comprehensive evaluation method and the weighted nearest neighbor method are compared, which indicated that the weighted nearest neighbor method supplied a better decision support during the spent fuel road transportation.