Smart grid: hope or hype?

The smart grid is an important but ambiguous element in the future transition of the European energy system. The current paper unpacks one influential national vision of the smart grid to identify what kinds of expectations guide the work of smart grid innovators and how the boundaries of the smart grid are defined. Building on data from a scenario exercise within a large Danish smart grid project, we examine how the smart grid and the conditions for its realization are defined and delimited. Our findings show that the smart grid hype embodies several implicit expectations that serve to guide research and investment and to attract new players into the field. A scenario process such as that demonstrated in this article can serve to articulate some of these implicit assumptions and help actors to navigate the ongoing transition. On the basis of our analysis, European policymakers might consider how their (intentional or unintentional) choices serve to create or maintain certain boundaries in smart grid development: for example, an exclusive focus on electricity within the broader context of a sustainable energy system. As serious investment starts being made in the smart grid, concepts like the supergrid, flexible demand and a broader smart energy system will start competing with each other.     

Hydrogen economy transition in Ontario – Canada considering the electricity grid constraints

This paper investigates the feasibility of electrolytic hydrogen production for the transport sector during off-peak periods in Ontario. This analysis is based on the existing electricity system infrastructure and its planned future development up to 2025. First, a simplified but realistic zonal based model for Ontario's electricity transmission network is developed. Then, based on Ontario's Integrated Power System Plan (IPSP), a zonal pattern of generation capacity procurement in Ontario from 2008 to 2025 is proposed, specifying the total effective generation capacity in each zone that contributes to base-load energy. Finally, an optimization model is developed to find the optimal size of hydrogen production plants to be developed in different zones, as well as optimal hydrogen transportation routes to achieve a feasible hydrogen economy penetration in Ontario up to 2025. The proposed model is shown to be an effective planning tool for electrolysis based hydrogen economy studies. The results of the present study demonstrate that the present and projected electricity grid in Ontario can be optimally exploited for hydrogen production, achieving 1.2–2.8% levels of hydrogen economy penetration by 2025 without any additional grid or power generation investments beyond those currently planned.     

Does environmental heterogeneity affect the productive efficiency of grid utilities in China?

China's electric power industry has experienced a reform whereby the generation sector is being opened up to competition but the transmission and distribution sectors are still under regulation. Efficiency and benchmarking analyses are widely used for improving the performance of regulated segments. The impact of observable environmental factors, together with unobservable characteristics, on efficiency has gained increasing attention in recent years. This study uses alternative stochastic frontier models combined with input distance functions to measure the productive efficiency of 29 grid firms of China over the period of 1993–2014 and investigates whether the observed environmental and unobserved heterogeneity factors affect the productive efficiency. The results indicate that adverse environmental conditions may bring negative influence to the production of grid utilities while the number of customers and the network length have positive impacts on the utilities' efficiency; Besides, the efficiency is sensitive to the model specification, which illustrates the presence of observed and unobserved heterogeneity; Moreover, there is no significant efficiency improvement in the grid utilities after the unbundling reform of 2002; Finally, the regional grids differ significantly in efficiency, and there is room for improvement, which could be achieved by incentive regulation taking due account of environmental heterogeneity.     

Optimal redundant placement of PMUs in Indian power grid — northern,eastern and north-eastern regions

Effective utilization of renewable energy sources and efficient management of electric energy are essential for any developing countries like India. This can be envisioned through the implementation of concepts of smart grid (SG). One of the key requisites for SG implementation is that the grid should be completely observable. Renovation of conventional Indian power grid to a SG necessitates incorporation of the phasor measurement units (PMUs) in the present power grid measurement and monitoring system. Since the cost of PMU is high and any bus containing a PMU makes the neighboring connected buses observable, optimal placement of PMUs is very important for complete observability of the grid. This paper proposes optimal redundant geographical locations in the northern, eastern and north-eastern regions of Indian power grid for PMU placement. The PMUs installed in these geographical locations will make the grid completely observable and maintain the observability under the conditions of failure of some PMUs or branch outages. Integer linear programming has been used for finding the optimal PMU locations. The results proposed in this paper can be a stepping stone for revamping the Indian power grid to a SG ensuring complete observability during different contingency conditions.     

Prospect of wind–PV-battery hybrid power system as an alternative to grid extension in Bangladesh

A pre-feasibility of wind-PV-battery hybrid system has been performed for a small community in the east-southern part of Bangladesh. Solar radiation resources have been assessed from other meteorological parameters like sunshine duration and cloud cover as measured radiation data were not available at the site. The predicted monthly averaged daily global radiation over Chittagong is 4.36 kWh/m²/day. Measured wind speed at the site varies from 3 m/s to 5 m/s. For few months and hours the speed is below the cut in speeds of the available turbines in market. The hybrid system analysis has showed that for a small community consuming 53,317 kWh/year the cost energy is 0.47USD/kWh with 10% annual capacity of shortage and produces 89,151 kWh/year in which 53% electricity comes from wind and the remaining from solar energy. The sensitivity analysis showed that the hybrid system for the community is compatible with the 8 km–12 km grid extension depending on small variation of solar radiation and wind speed over the district whereas the proposed site is more away from the upper limit. Such a hybrid system will reduce about 25 tCO₂/yr green house gases (GHG) emission in the local atmosphere.     

When does decentralized production of biogas and centralized upgrading and injection into the natural gas grid make sense?

The production of biogas through anaerobic digestion is one of the technological solutions to convert biomass into a readily usable fuel. Biogas can replace natural gas, if the biogas is upgraded to green gas. To contribute to the EU-target to reduce Green House Gases emissions, the installed biogas production capacity and the amount of farm-based biomass, as a feedstock, has to be increased. A model was developed to describe a green gas production chain that consists of several digesters connected by a biogas grid to an upgrading and injection facility. The model calculates costs and energy use for 1 m³ of green gas. The number of digesters in the chain can be varied to find results for different configurations. Results are presented for a chain with decentralized production of biogas, i.e. a configuration with several digesters, and a centralized green gas production chain using a single digester. The model showed that no energy advantage per produced m³ green gas can be created using a biogas grid and decentralized digesters instead of one large-scale digester. Production costs using a centralized digester are lower, in the range of 5 €ct to 13 €ct per m³, than in a configuration of decentralized digesters. The model calculations also showed the financial benefit for an operator of a small-scale digester wishing to produce green gas in the cooperation with nearby other producers. E.g. subsidies and legislation based on environmental arguments could encourage the use of decentralized digesters in a biogas grid.     

Adaptive fuzzy control with an optimization by using genetic algorithms for grid connected a hybrid photovoltaic–hydrogen generation system

The integration of significant amounts of renewable-storage hybrid power generation systems to the electric grid poses a unique set of challenges to utilities and system operators. This article deals with the designing methodology of an intelligent control based grid-connected a hybrid system composed of renewable energy source (RES) and storage system (SS). RES is a photovoltaic (PV) source and SS is a process of hydrogen transformation system (H₂TS) which composed of alkaline water electrolysis (AWE) for decomposition water by using the PV power, a tank used for gas storage and a proton exchange membrane (PEM) fuel cell (FC) to transform the H₂ to the electrical energy. The interconnection of the grid with the power generation system (PGS) is ensured through using a DC/AC hysteresis converter and it can synchronize current with the grid voltage among an independent control of active (P) and reactive (Q) power through a possibility of the Q compensation. In the proposed system, three algorithms are applied; two used inside generation and the third is used inside the grid. Perturb and observe (P&O) maximum power point tracking (MPPT) control algorithm always finds optimal power in the PV generator. A simple cascade controls loop of DC-DC boost converter and operate the FC generator to ensure maximum power and to regulate the DC Bus voltage. In addition, adaptive fuzzy logic control (FLC) unit is developed to control the DC/AC inverter, with adopting an off-line optimization based on genetic algorithms (GAs) applauded for tune different issues as scaling factors of the FLC and PIDs gains of the PV and the H₂TS control loops. Simulated results prove a big success of the proposed controls of the grid connected the hybrid PV-H₂TS with good performance.     

Kalman Filter bank post-processor methodology for the Weather Research and Forecasting Model wind speed grid model output correction

The performance of the Weather Research and Forecasting (WRF) model, coupled with a bank of eight Kalman Filters (KFB) as a post-processor toolbox for the three hourly average WRF wind speed forecasts, is investigated and compared to the output of the WRF model alone. Two model set-ups, WRF and WRF+KFB, have been tested for the period January to December 2008 on nine locations corresponding to gradient wind towers of the Cuban Eolic program. Tests demonstrated that the KFB post-processing technique, using a third-order polynomial, combined with a four-point a priori moving window averager for covariance matrix computation, was the best configuration for improving the WRF grid model day-ahead wind speed forecast output. The WRF+KFB approach investigated has been shown to adapt to changing wind speed patterns and to offer improved wind speed forecasts for each location considered, whilst only requiring a limited data set for training purposes.     

What is the most suitable fixed grid solidification method for handling time-varying inverse Stefan problems in high temperature industrial furnaces?

This paper presents a simple inverse heat transfer method for predicting the time-varying bank thickness of the phase change protective layer inside a high temperature furnace. The direct problem is handled with the single phase method which is neglecting the latent heat. The inverse method rests on the Adjoint Problem and the Conjugate Gradient Method. It is shown that the iterative inverse procedure based on the single phase method predicts a virtual incident heat flux in the liquid zone that yields accurate time-varying bank predictions. Results also indicate that the benefits of the virtual iterative approach are twofold: the CPU time required for solving the inverse problem is reduced and the lagging effect inherent to the inversion is diminished for non isothermal phase change processes. For typical melting furnace operating conditions, it is shown that the virtual approach doubles the allowable diagnostic frequency for predicting the time-varying bank thickness.     

Parking the power: Strategies and physical limitations for bulk energy storage in supply–demand matching on a grid whose input power is provided by intermittent sources

It is shown that, in a sustainable energy future, energy for the electricity grid will probably be derived largely from the renewable sources of wind and solar radiation. Because both are intermittent, any infinite busbar grid supplying a metropolitan area must necessarily be buffered from these intermittencies by massive energy storage on the gigawatt-day level. It is then demonstrated that, under presently foreseeable scientific capabilities, only underground pumped hydro and advanced adiabatic compressed air energy storage appear capable of meeting anticipated technological and economic constraints. Neither has ever been constructed and tested; but even so it is predicted that underground pumped hydro ultimately will prove to be superior.     

Evaluating the impact of the administrative procedure and the landscape policy on grid connected PV systems (GCPVS) on-floor in Spain in the period 2004–2008: To which extent a limiting factor?

The growth of the Spanish photovoltaic (PV) sector in the period 2004–2008 rendered Spain a prominent place among top worldwide countries. Yet, this growth was rather uneven across the different Spanish regions which raised the interest on the drivers ultimately effecting these disparities. Especially controversial were the arguments about the influence of the administrative procedure and the landscape policy on the development of GCPVS on-floor. This study therefore discloses both two elements and evaluates their impact in a group of PV prominent Spanish regions and Catalonia, the latter used as a benchmark because of its comprehensive and stringent regulation on landscape protection, which was accused by the PV industry of thwarting the development of the GCPVS on-floor. Both quantitative and qualitative analyses were carried out. In particular two indexes were elaborated to determine the consistency of the arguments pointing to the landscape protection policy as a decisive barrier to GCPVS growth. First, when the analysis is made in relative terms, the ranking of PV prominent regions changes and many of the differences vanish. Second, rather than the preeminence of a landscape protection policy what really matters for GCPVS on-floor growth is the administrative procedure and the processing enabling its implementation.