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As a low‐rate and low‐power network, IPv6 over low‐power wireless personal area network (6LoWPAN) wireless sensor network (WSN) suffers from considerable data communication latency and rapid energy depletion which data transmission mainly accounts for. Therefore, it is significant to reduce data communication latency and balance the energy consumption among sensor nodes to avoid the situation that a sensor node transmits a large content. To achieve these two objectives, the authors are motivated to extend the k ‐anycast communication model to 6LoWPAN WSN so that the different parts of a large content can be provided by multiple optimal k ‐anycast members in parallel. In this way, content communication latency can be reduced and energy consumption caused by content transmission can be shared by these members. This proposal is evaluated and the data results show that this proposal effectively reduces the content communication latency and achieves the energy consumption balance. [ABSTRACT FROM AUTHOR]

The paper proposes a routing scheme for IPv6-based all-IP wireless sensor networks. The paper creates the IPv6 address structure and the IPv6 address configuration algorithm for all-IP wireless sensor networks. Based on the IPv6 address structure, the paper proposes the routing algorithm in the link layer for all-IP wireless sensor networks. In the routing scheme, a sensor node stores the next channel-sampling time of its neighbor nodes. In this way, only during the next channel-sampling time, a sensor node keeps active. and during any other time it returns to sleep. Therefore, the routing performance is improved. and the power consumption is reduced. Finally, the paper discusses the reduced IPv6 protocol stack performing the routing scheme. The routing scheme's performance parameters are evaluated, including routing power consumption and delay, and the data results show the correctness and efficiency of the scheme. [ABSTRACT FROM AUTHOR]

Recently, underwater wireless sensor networks (UWSNs) have been considered as a powerful technique for many applications. However, acoustic communications in UWSNs bring in huge QoS issues for time-critical applications. Additionally, excessive control packets and multiple copies during the data transmission process exacerbate this challenge. Faced with these problems, we propose a reliable low-latency and energy-efficient transmission protocol for dense 3D underwater wireless sensor networks to improve the QoS of UWSNs. The proposed protocol exploits fewer control packets and reduces data-packet copies effectively through the co-design of routing and media access control (MAC) protocols. The co-design method is divided into two steps. First, the number of handshakes in the MAC process will be greatly reduced via our forwarding-set routing strategy under the guarantee of reliability. Second, with the help of information from the MAC process, network-update messages can be used to replace control packages through mobility prediction when choosing a route. Simulation results show that the proposed protocol has a considerably higher reliability, and lower latency and energy consumption in comparison with existing transmission protocols for a dense underwater wireless sensor network. [ABSTRACT FROM AUTHOR]

In a conventional fuel vehicle, it is always difficult to find design points for a thermoelectric generator (TEG) because of the variation in engine power seen in different driving cycles. In contrast, the engine of an extended-range electric vehicle (EEV) is decoupled from the road load and only works at a single operating point in most cases, making it particularly suited for a TEG optimization design. This paper describes a method to match an optimized TEG to an EEV based on two criteria: TEG protection and high net power density. The trade-offs for TEG performance from TEG weight, added electric pump power consumption and backpressure are all taken into consideration. On this basis, the electric load resistance and configuration of the TEG are optimized, achieving a 11.6% increase of net power density compared to a preliminary designed TEG. The fuel economy of the optimized TEG integrated in an EEV (EEV-TEG) is assessed against that of a conventional EEV. The comparison shows that a 1.7% reduction in equivalent fuel consumption is obtained by the EEV-TEG, which is higher than that of a TEG applied in conventional fuel vehicles. These results exhibit the crucial importance of the method of matching and optimization for a TEG applied to EEVs. • A method of matching and optimization for a TEG in EEVs application is proposed. • The fixed design points for a TEG in EEVs application in EEVs have been identified. • TEG protection and high net power density are the two criteria for TEG optimization. • Both electric load resistance and configuration of the TEG have been optimized. • The optimized TEG applied in EEV decreases the fuel consumption by 1.7%. [ABSTRACT FROM AUTHOR]

• Methane yield increased by 150% by adding activated carbon into thermophilic AD. • Activated carbon enhanced hydrogenotrophic methanogenesis in thermophilic digestion. • Activated carbon improved environmental impacts of anaerobic digestion based on LCA. • The dosage of activated carbon is a crucial parameter to determine LCA profile. Anaerobic digestion (AD) is widely used to recover energy (in the form of methane) and nutrients (in the form of biofertilizer) from organic wastes, and adding conductive materials has been reported to be an effective way to enhance AD efficiency. However, the process performance and environmental sustainability of adding conductive materials into AD under different temperature conditions have not been addressed. In this study, four different groups of lab-scale reactors were operated under both mesophilic and thermophilic conditions and with/without activated carbon (AC) addition. Based on the lab-scale results, a pilot-scale reactor was used to highlight the effectiveness of activated carbon addition, and the derived data was used for a life cycle assessment (LCA) study. The results showed the enhancement of methane production by adding AC, particularly under thermophilic conditions. At the organic loading rate of 4.7 g VS/L/d, the average methane yield of the thermophilic AD reactors with AC was 550 mL CH 4 /g VS, which was significantly higher than that of the control reactors (i.e. 220 mL CH 4 /g VS). Adding AC into AD reactors accelerated the shift of dominant methanogenic pathways from aceticlastic methanogenesis to hydrogenotrophic methanogenesis by enriching Methanoculleus (84% of total archaea). The LCA results highlighted the environmental benefits of using activated carbon to enhance AD of food waste at both midpoint and endpoint levels based on ReCiPe2016 methodology. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Energy demand side management is optimized to improve the system performance. • A game theoretic approach for distributed energy management is developed. • Energy supply constraints and storage facilities are evaluated. • Blockchain technology is applied for efficient and trustable micro-grid operation. • Decentralized energy supply and demand management is implemented in practice. Abstract The management of energy supply and demand is becoming more challenging, especially in regions where the demand continues to grow rapidly and more intermittent renewable supply sources are added to the energy infrastructure. In this context, Demand Side Management (DSM) can be employed to align supply and demand and improve reliability of the system under supply constraints and stretch the capacity limits of the existing grid infrastructure. A game theoretic approach for a DSM model incorporating storage components is suggested in this paper especially for environments with energy supply constraints. The proposed model is able to not only reduce the Peak-to-Average ratio to benefit the electrical grid, but can also smoothen the dips in the load profile caused by supply constraints. In a case study to demonstrate the value of the model presented, a variety of residential demand types are evaluated within a micro-grid to maximize the payoff utility of both individual users and the whole system. Moreover, emerging blockchain technologies are introduced to guarantee the seamless and secure implementation of the proposed scheme, illustrating how a decentralized demand side management approach could be implemented in practice to facilitate peer-to-peer transactions following optimized demand profiles. [ABSTRACT FROM AUTHOR]

The multi-generation system often operates under off-design conditions due to the highly dynamic energy demand. Improving its off-design performance is crucial for energy conservation and emission reductions. To this end, this paper proposed a novel control strategy for the gas turbine cycle applied in combined heating and power (CHP) system, which effectively combines turbine inlet temperature control (TITC) and inlet air throttling control (IATC) methods, to improve system off-design performance and avoid discharging low-temperature gas. The hybrid control strategy can improve system efficiency by 3.70% on average over the traditional TITC method during the entire load range. Moreover, the maximum efficiency difference between these two methods reached 5.15% at the 30%-load factor conditions. To further showcase the effectiveness of the IAT-TITC method, the CHP system is integrated with an electric chiller and thermal refrigeration, respectively, forming four combined cooling, heating, and power (CCHP) system scenarios to supply the energy for a hotel building. Not only did the CCHP system scenarios with the IAT-TITC method show better performance, but also considering an electric chiller as an extra cooling supply machine can reduce primary energy consumption by 30.73%, 28.32%, and 11.56% in summer, transition season, and winter typical days, respectively, compared with separation system. • An off-design modeling framework to capture CHP system performance is developed. • A novel operating strategy for improving CHP system performance is proposed. • CHP system is integrated into CCHP system scenarios for hotel building applications. • CCHP performance is analyzed in detail in terms of energy, economy, and environment. [ABSTRACT FROM AUTHOR]

The design of low-carbon energy systems towards sustainable cities requires correctly quantifying uncertainties in future climate variations, since they affect both energy demand of urban cities and energy system performance. However, quantifying climate uncertainties is challenging due to the stochastic and unpredictable nature of future climate events. This paper develops a novel and general framework to quantify climate uncertainties for urban energy system design using scenario-based stochastic optimization. Climate models are coupled with building performance simulation to generate scenarios for uncertainty quantification and energy system optimization. We apply this optimization framework to US cities for demonstration. We find that climate uncertainties in renewable generation and energy demand can lead to significant performance differences in urban energy systems. Neglecting climate uncertainties results in an optimistic energy system; however, it is unable to provide stable power supply to urban cities. Moreover, we observe that maintaining a certain degree of grid integration is beneficial for urban energy systems and can alleviate the economic burden of urban cities. Finally, we provide some valuable insights on urban energy systems for system designer and policymakers. The designers should fully consider uncertainties associated with various climate events during system design and deploy proper backup systems in case of contingency. The policymakers should thoroughly account for climate uncertainties and their resulting costs when stipulating energy policies for promoting low-carbon energy systems. Both designers and policymakers need to cooperate together and coordinate their actions on urban energy systems towards sustainable cities. • The uncertainties in climate change are quantified using stochastic scenarios. • A novel stochastic optimization framework is proposed for urban energy system design. • Neglecting climate uncertainties results in optimistic energy systems that suffer from loss of load. • Valuable insights on urban energy systems are provided for both designers and policymakers. [ABSTRACT FROM AUTHOR]

[Display omitted] • 100% renewable island energy system with P2G, biogas and desalination technologies. • An integrated approach for demand prediction, design and dispatch optimization. • Influence of extreme weather is considered. • Desalination and biogas technologies can increase the resilience of the proposed system. • P2G technology is more economic beneficial than battery storage for the case study. Islands are constrained by geographical conditions in terms of energy delivery. Due to weak connections with the mainland and the power grid, the diversity of island energy demand leads to high economic costs and environmental pollution issues. This study proposes a 100% renewable island energy system, which integrates with power-to-gas, combined cooling, heating and power, and desalination technologies to supply electricity, heating, cooling, gas and fresh water to the local residents. A comprehensive approach for energy demand prediction, system design and dispatch optimization, as well as system evaluation is proposed. For energy demand prediction, agent-based modeling is used to simulate the demand of electricity, heating, cooling, gas and fresh water for the case study community on the island. The k-means clustering and scenario tree are further adopted to generate representative stochastic scenarios, which are applied to capture the uncertainty of energy demand. A multi-objective optimization model is developed to optimize the system design and scheduling strategy simultaneously. In order to demonstrate the effectiveness of the proposed approach and to evaluate the obtained optimal solutions for the case study, different objectives and extreme weather conditions are specifically considered. The optimal solution obtained shows that compared to battery storage, a 2.5% annual cost reduction can be achieved by using power-to-gas technology for energy storage. The findings also suggest that extreme weather conditions can be coped with by increasing the capacity of biogas generation, desalination, and energy storage equipment, thereby improving the resilience of the island energy system. [ABSTRACT FROM AUTHOR]

Abstract: To reduce the nutrient cost of l-lactic acid production, wheat bran was chosen as a nutrient source. Various pretreatment processes were investigated, and 80°C for 20h by acid-hydrolysis was a suitable method considering the energy consumption. Pretreated wheat bran showed a better performance than that without treatment, especially for l-lactic acid yield (0.99g/g). Moreover, when 25g/l wheat bran hydrolysate was combined with 30g/l corn steep liquor, the l-lactic acid fermentation efficiency (yield 0.99g/g, productivity 3.75g/l/h) was even higher than that of the control with 15g/l yeast extract (yield 0.95g/g, productivity 2.46g/l/h). Although much more wheat bran hydrolysate and corn steep liquor were used than yeast extract in total amount, the cost of nitrogen in fermentation was estimated to be ¥1286/t l-lactic acid (25g/l wheat bran hydrolysate and 30g/l corn steep liquor), which is only 11% of the ¥11471/t l-lactic acid (15g/l yeast extract) in control test. Therefore, nutrients of wheat bran hydrolysate and corn steep liquor could be employed to substitute yeast extract for l-lactic acid production. [Copyright &y& Elsevier]