An analysis of storage revenues from the time-shifting of electrical energy in Germany and Great Britain from 2010 to 2016

The purpose of this paper is to investigate the level of revenues available to storage operators through the bulk time-shifting of electrical energy in Germany and Great Britain over the 7 years from 2010 to 2016, and to analyse the impact of volatility and underlying mean price on the potential revenues that a storage operator could theoretically capture. The analysis is carried out using an algorithm adapted from previous work, coupled with new empirical hourly price data from the German and Great British day-ahead electrical markets, and using characteristics typical of a pumped-storage hydropower scheme (1000 MWh, 125 MW charge and discharge, and 75% round-trip efficiency). Our results suggest that volatility rather than average price is the dominant factor affecting storage revenues, with a 1% increase in volatility implying an increase in mean daily storage revenues of €300 in Germany and £550 in Great Britain for the simulated storage plant. In comparison, an increase in underlying mean prices of €1 per MWh leads to an increase in mean daily revenue of €100 in Germany, with a £1 per MWh increase in underlying mean prices leading to an increase in mean daily revenue of £380 in Great Britain. We also find that during the period 2010–2016, the times when the highest revenue is derived have moved from late morning to early evening, which we attribute to the increase in low short-run marginal cost solar PV electricity in both markets suppressing the day-ahead wholesale electrical prices. In addition, we find a large increase in storage operator revenues in Britain in the last quarter of 2016, due to a number of events that impacted the price of electricity, however these would have been difficult to predict with any degree of certainty. This paper therefore highlights the perennial problem of forecasting the time-shifting revenue for electrical energy, with its high degree of variation from one year to the next that would undoubtedly impact the financing of these capital-intensive projects that seek to capture these variable revenues

The transition towards a sustainable energy system in Europe: What role can North Africa's solar resources play?

Securing energy supply and speeding up the transition towards a reliable, sustainable, low-carbon energy system are among the major current and future challenges facing Europe. Importing dispatchable solar electricity from North Africa is considered as a potential and attractive option. Nevertheless, as things currently stand, the European Commission focuses mainly on the exploitation of the existing wind power potential in the North Sea, largely ignoring the solar power potential in the Sahara region of North Africa. After discussing the major challenges and issues facing Europe to achieve the assigned ambitious objectives, the paper emphasises the importance of North Africa's solar resources in helping Europe to successfully address the challenge of decarbonising its electricity system, in particular with regards to the security of supply and sustainability. Within these two major challenges, the paper explores the issues of access, barriers and opportunities. The paper highlights why the EU’s energy and climate goals will not be achievable without adequate grid expansion and grid-scale energy storage facilities, as well as other innovative measures to manage demand and ensure a secure energy supply. In this respect, the paper shows how the import of dispatchable electricity from North Africa via specific HVDC links could play a key role in helping the EU achieve its energy targets in a cost effective way without recourse to significant investments in transmission infrastructure and storage facilities. The paper then attempts to identify and analyze the main barriers that continue to inhibit the export of solar electricity from North Africa to Europe. Finally, to make the project more attractive and achievable in the near future, the paper proposes a systematic approach for setting up energy import scenarios. A promising import scenario is presented where energy import via Italy is shown to be a more viable and effective solution than via Spain.Peer reviewe

Demonstration of CO2 conversion to synthetic transport fuel at flue gas concentrations

A mixture of 1-and 2-butanol was produced using a stepwise synthesis starting with a methyl halide. The process included a carbon dioxide utilization step to produce an acetate salt which was then converted to the butanol isomers by Claisen condensation of the esterified acetate followed by hydrogenation of the resulting ethyl acetoacetate. Importantly, the CO 2 utilization step uses dry, dilute carbon dioxide (12% CO 2 in nitrogen) similar to those found in post-combustion flue gases. The work has shown that the Grignard reagent has a slow rate of reaction with oxygen in comparison to carbon dioxide, meaning that the costly purification step usually associated with carbon capture technologies can be omitted using this direct capture-conversion technique. Butanol isomers are useful as direct drop-in replacement fuels for gasoline due to their high octane number, higher energy density, hydrophobicity, and low corrosivity in existing petrol engines. An energy analysis shows the process to be exothermic from methanol to butanol; however, energy is required to regenerate the active magnesium metal from the halide by-product. The methodology is important as it allows electrical energy, which is difficult to store using batteries over long periods of time, to be stored as a liquid fuel that fits entirely with the current liquid fuels infrastructure. This means that renewable, weather-dependent energy can be stored across seasons, for example, production in summer with consumption in winter. It also helps to avoid new fossil carbon entering the supply chain through the utilization of carbon dioxide that would otherwise be emitted. As methanol has also been shown to be commercially produced from CO 2 , this adds to the prospect of the general decarbonization of the transport fuels sector. Furthermore, as the conversion of CO 2 to butanol requires significantly less hydrogen than CO 2 to octanes, there is a potentially reduced burden on the so-called hydrogen economy

HVDC links between North Africa and Europe: Impacts and benefits on the dynamic performance of the European system

This document is the Accepted Manuscript version of the following article: Mokhtar Benasla, Tayeb Allaoui, Mostefa Brahami, Mouloud Denai, and Vijay K. Sood, ‘HVDC links between North Africa and Europe: Impacts and benefits on the dynamic performance of the European system’, Renewable and Sustainable Energy Reviews, November 2017. Under embargo. Embargo end date: 20 November 2018. The published version is available online at doi: DOI: https://doi.org/10.1016/j.rser.2017.10.075. Published by Elsevier Ltd. This manuscript version is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.In the last decade, there have been several initiatives for the deployment of cross-Mediterranean HVDC (High Voltage Direct Current) links to enable the transmission of electrical power from renewable energy sources between North Africa and Europe. These initiatives were mainly driven by the potential economic, environmental and technical benefits of these HVDC interconnections. In previous studies on these projects, some technical aspects of critical importance have not been addressed or studied in sufficient detail. One of these key aspects relates to the impact and possible benefit of these HVDC links on the dynamic performance of the European system which is the major focus of this paper. Several issues relating to the dynamic performance of the system are addressed here. Based on the experience gained from existing AC/DC projects around the world, this paper shows that the HVDC links between North Africa and Europe can greatly improve the dynamic performance of the European system especially in the southern regions. In addition, some challenges on the operation and control of these HVDC links are highlighted and solutions to overcome these challenges are proposed. This review paper, therefore, serves as a preliminary study for further detailed investigation of specific impacts or benefits of these interconnections on the overall performance of the European system.Peer reviewe

Utilizing the flexibility of distributed thermal storage in solar power forecast error cost minimization

Highlights • Combines dynamic optimization and numerical weather prediction (NWP). • Annual solar PV forecast error cost for the 1 MWp plant is 830€. • Solar PV generation imbalances reduced by 10% with demand side management. • Average and marginal benefits per household decrease with increasing network size.Intermittent renewable energy generation, which is determined by weather conditions, is increasing in power markets. The efficient integration of these energy sources calls for flexible participants in smart power grids. It has been acknowledged that a large, underutilized, flexible resource lies on the consumer side of electricity generation. Despite the recently increasing interest in demand flexibility, there is a gap in the literature concerning the incentives for consumers to offer their flexible energy to power markets. In this paper, we examine a virtual power plant concept, which simultaneously optimizes the response of controllable electric hot water heaters to solar power forecast error imbalances. Uncertainty is included in the optimization in terms of solar power day-ahead forecast errors and balancing power market conditions. We show that including solar power imbalance minimization in the target function changes the optimal hot water heating profile such that more electricity is used during the daytime. The virtual power plant operation decreases solar power imbalances by 5–10% and benefits the participating households by 4.0–7.5 € in extra savings annually. The results of this study indicate that with the number of participating households, while total profits increase, marginal revenues decrease

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Impact of Variable Renewable Energy on European Cross-Border Electricity Transmission

The estimated growth of Europe’s electricity demand and the policy goals of mitigating climate change result in an expected increase in variable renewable energy. A high penetration of wind and solar energy will bring several new challenges to the European electricity transmission network. The objective of this paper is to understand the effects of a high penetration of variable renewable energy sources (RES) on the demand for cross-border electricity transmission in Europe. EUPowerDispatch, a minimum cost dispatch model is used to compare the impacts of different electricity generation and transmission portfolios on crossborder electricity transmission in 2025. The analysis makes use of the best-estimate scenario developed by the European Network of Transmission System Operators for Electricity (ENTSOE). Wind and solar energy curtailment needs and variations in load duration curves are analyzed for different scenarios. In addition, the role of hydro energy storage and pumping is analyzed as a complementary technology to transmission in the context of a high penetration of variable RES. The study shows that the planned expansion of the European transmission network is adequate for meeting the expected RES increase and it is needed to maintain the current level of security of supply in the face of the expected demand growth. If RES growth is faster than expected, cross-border transmission capacity will have to increase accordingly if significant RES curtailment is to be avoided.Infrastructures, Systems and ServicesTechnology, Policy and Managemen