Abstract

A variety of energy-saving concepts that exploit the special characteristics of electric drives are introduced. The confluence of three emerging concepts in transportation, namely electric drives, autonomous driving, and networked vehicles, enables the optimization of transportation efficiency in a way that drastically changes modern transportation, especially for passenger and commercial road vehicles. The paper addresses both, urban as well as highway driving situations and the associated optimization problems. It is shown that if the only term in the cost function is transportation energy, and all other conditions are formulated as constraints, quite substantial energy cost reductions are possible. Exploiting weather and environmental conditions is another important topic that is analyzed. The paper illustrates key ideas via several simulation examples.

Abstract

Surface polaritonic modes like surface plasmon polaritons (SPPs) and surface phonon polaritons (SPhPs) at interfaces can significantly enhance near-field radiative transfer between nanostructured surfaces. In this work, we study the near-field heat transfer between graphene/SiC composite nanostructures. It is demonstrated that thermally excited SPPs and SPhPs in such composite nanostructures lead to a significant enhancement in nearfield heat transfer rate. To further analyze the underlying mechanisms, we calculate energy transmission coefficients and obtain the near-field dispersion relations. The dispersion relations of composite nanostructures are substantially different from those of isolated graphene or SiC films, which are due to the strong coupling effects between different polaritonic modes. We further identify four pairs of strongly coupled polaritonic modes with considerable Rabi frequencies, which mainly contribute to the enhancement in near-field heat transfer. This work provides a route to utilize strongly coupled surface polaritonic modes to manipulate near-field heat transfer, which has potential applications in waste heat recovery and heat management.

Abstract

This article analyses drivers and barriers for renewable energy investments, and provides three suggestions to reduce investment risk.

Abstract

This paper suggests a model for optimization of societal carbon footprints one person at a time through the decentralization of electricity use and accounting. Our model describes steps involved with developing a decentralized accounting system considering electricity as a “credit product”. While describing the basic characteristics of both schemes, we also emphasize capabilities of the proposed model for reducing carbon footprints from other societal choices, for example, purchasing water (energy-water nexus), managing waste, or designing sustainable transportation systems. A simple yet complex model involved with familiar societal financial systems’ rules and routines is proposed for achieving a resilient, sustainable, and prosperous future. The proposed model calls for creating a dynamic society (as a system) that can be efficiently adopted to take on challenges threatening the function, survival, and future developments of the societies.

Abstract

Hydrogen is recognized as an environmentally clean energy source for electricity generation, alternative fuel and other applications since it is zero emission. Coal is one important source for hydrogen production, which has special value for China because it’s rich in coal but limited in natural gas and oil. More important, coal can be utilized in low carbon way through integrating CO2 capture into hydrogenation production process. However, with the current technology, the energy efficiency of producing hydrogen from coal is around 60%, which limits the full chain efficiency of coal utilization. It is therefore extremely important to develop more efficient methods of H2 production from coal. In this paper, a new type of hydrogen production process with a three-step coal gasification is introduced. The Aspen Plus Software is selected to simulate the system. Then the Exergy-Utilization Diagram (EUD) analyses are applied to disclose the mechanism of key processes. The result reveals that the efficiency of hydrogen production can be upgraded to 67% due to removing air separation unit and CO2 separation process. Thereby the hydrogen production process introduced in this paper has a good thermodynamic performance and may provide a quite promising way for high efficient and clean coal utilization.

Abstract

The focus of this paper is on the estimation of building roof area for solar PV systems, potential solar PV installed capacity and power generation in Vasteras, a typical Swedish municipality. The following sectioning of different building types has been investigated: Residence, Industry, Social function, Business, Economy, Complement, and Others. In the following sections, an estimate of available roof area potential is calculated by considering factors such as rooftop orientation, shadows and obstacles. With appropriate rooftops covered with commercial solar cells, combined with the average solar irradiation, PV panel efficiencies and other system parameters, the total solar power potential PV peak power output from the region is considered and the potential annual energy production is calculated. This will give a picture of how much the electricity demand will be met by rooftop PV deployment. We get those new understanding of roof area distribution and potential outputs that can largely help solar energy policy formulation in the city.

Abstract

Dense oxygen permeable membrane supported water splitting is a potential technology for high purity hydrogen production. It utilizes thermochemical energy to split water to hydrogen with the membrane separating the products so that the water splitting extent is not constrained by its thermodynamic equilibrium. Meanwhile, when methane partial oxidation is integrated into the other side of the membrane, syngas is co-produced with stoichiometry H2/CO = 2. The carbon species will not mix with the H2/H2O mixture on the water side since the dense membrane is selective to oxygen permeation only. In this paper, the co-production of high purity hydrogen and syngas is studied in a monolith membrane reactor, and a computational model is developed to study the reactor performance and the associated material cost. Two types of membranes are investigated, i.e., La0.9Ca0.1FeO3-δ (LCF) and BaCoxFeyZrzO3-δ (BCFZ) membranes. Results show that the required BCFZ membrane surface area for the production of 100 kmol H2/h (from water splitting) is 5.3 times smaller than the required LCF area under base case conditions. Moreover, the cost study shows that the raw material cost depends on the price of the critical minerals such as cobalt, which are uncertain due to the demand and supply imbalance. Therefore, developing membrane materials with less critical minerals can benefit the implementation of the membrane reactor in an industry-scaled hydrogen production plant.

Abstract

In order to alleviate energy shortages and environmental pollution problems, new energy vehicles have become an important development direction of the automotive industry today, including electric vehicles, hybrid vehicles, hydrogen-powered vehicles and so on. At present, China has the advantage of becoming the world’s largest electric vehicle market, accounting for about half of global sales. International automakers are also investing heavily in China. The energy consumption of Chinese cars is in the stage of upgrading from fossil fuels to clean energy. Energy conservation and emission reduction are also important issues for the Chinese government. In this research context, this study attempts to establish a CGE model based on the data of Guangdong social accounting matrix to simulate the change of energy prices under the policy promotion and the reduction of automobile fossil fuel consumption for the economic system. The impact of simulating the improvement of environmental pollution caused by structural changes in energy use provides a scientific basis for the government’s macro decision-making. This study is mainly aimed at the economic impact of consumer preferences change caused by government’s policies and publicity to promote the new energy vehicle development, we divided the energy use transformation into 2 ways: general and high level promotion. In each stage, we simulated the macroeconomic impacts and found significant changes caused by consumption structure change.

Abstract

Certification by the Leadership in Energy and Environmental Design (LEED) program is often proposed as a potential method to improve building energy efficiencies. This is despite the general lack of data regarding the efficacy of LEED certification and inconsistent results from past studies that often focused on a few buildings from a single city. Using recently available building energy use data from a nationwide set of 10 cities, we studied the effects of LEED certification on building energy efficiency measured by site energy use intensity, source energy use intensity, and greenhouse gas emissions. In addition, we used natural language processing methods to study patterns in the acquisition of specific credits by LEED-certified buildings. We find that LEED-certified buildings are not more energy-efficient by any measure except in a single city. In addition, neither the total amount of credits nor the number of Energy and Environment credits achieved correlate with building energy efficiency measures. Finally, buildings with high Energy and Atmosphere credits corresponding to renewables are not more energy-efficient in many cases. These conclusions call into question the use of LEED certification as a policy metric for improving the energy efficiency of buildings.

Abstract

The characteristics of fossil fuels (low-cost storage, economic variable output enabled by low-capitalcost high-operating-cost power systems, etc.) have resulted in an energy system where fossil fuels separately supply energy to the electricity, industrial (heat) and transport (liquid fuels) sectors. World systems are undergoing a profound change driven by (1) large-scale addition of wind and solar and (2) the goal of a low-carbon electricity grid. Nuclear, wind and solar have high capital costs and low operating costs where the cost of energy increases rapidly if operate at part load. We examined integrating the electricity and industrial sectors by (1) nuclear co-generation with production of heat for industry and electricity and (2) addition of heat storage to increase reactor capacity factors. This system design substantially reduces total energy costs by three separate mechanisms. Modeling of electricity and industrial energy systems shows nuclear cogeneration reduces energy costs by changing the hourly energy demand curves to better match production from low-carbon energy sources resulting in higher power-plant utilization. Cogeneration enables optimizing the electricity and industrial sector by varying industrial production to minimize total costs with added electricity sales at times of high prices. Heat storage increases plant capacity factors and thus lowers total energy costs.