Review and analysis of energy storage systems by hydro-pumping to support a mix of electricity generation with a high percentage of renewables

In some countries the planning of the electricity generation mix for the future includes a considerable increase in Renewable Energy (RE) to reduce the emissions caused by the use of fossil fuels. This trend can be reinforced if the installed power capacity of nuclear and coal plants is considerably decreased. On the other hand future electricity demand seems to increase due to population growth and greater domestic electrification, especially if transport electrification is tackled. The combination of these factors may result in an ever greater decline in Security of Supply (SoS), mainly due to the stochastic nature of electricity supply and demand behaviour. To achieve an acceptable level of SoS when introducing renewable energy into the grid it is necessary to increase storage capacity and tackle other measures such as demand management. Many energy storage technologies can be found, and Pumped Hydro Energy Storage (PHES) is recognised as the most mature, though other technologies such as batteries are also available. In this paper, we first review PHES and its ability to support intermittent generation from energy plants, such as wind and solar, preventing energy losses and storing energy for use at times of high demand; second we analyse the performance of PHES in Spain over five years (2014-2018); our conclusion confirms that adequate SoS cannot be guaranteed with PHES management of the kind observed in the past.This research is supported by the Basque Government through the BERC 2018-2021 programme and by the Spanish Ministry of Economy and Competitiveness (MINECO) through BC3 María de Maeztu excellence accreditation MDM-2017-0714.Further support is provided by the project MINECO RTI2018-093352-B-I0

Old Wind Farm Life Extension vs. Full Repowering: A Review of Economic Issues and a Stochastic Application for Spain

The installation of wind power technology is growing steadily and the trend can be expected to continue if the objectives proposed by the European Commission are to be achieved. In some countries a considerable percentage of installed wind power capacity is near the end of its useful lifetime. In the case of Spain, the figure is 50% within five years. Over the last 20 years, wind energy technology has evolved considerably and the expected capacity factor has improved, thus increasing annual energy production, and capital expenditure and operational expenditure have decreased substantially. This paper studies the optimal decision under uncertainty between life extension and full repowering for a generic wind farm installed in the Iberian Peninsula when the future hourly electricity prices and the capacity factor evolve stochastically and seasonally. The results show that in economic terms, full repowering is the best option, with a net present value of €702,093 per MW installed, while reblading is the second best option. The methodology can be transferred to other specific wind farms in different electricity markets and can be used to develop national wind energy policy recommendations to achieve projected shares in the electricity mix.This research was funded by the Basque Government through the BERC 2018–2021 programme and by the Spanish Ministry of the Economy and Competitiveness (MINECO) through BC3 María de Maeztu excellence accreditation MDM-2017-0714. Further support is provided by the MINECO project RTI 2018-093352-B-I00

Optimal Slow Steaming Speed for Container Ships under the EU Emission Trading System

Slow steaming is an operational measure in ocean-going vessels sailing at slow speeds. It can help climate mitigation efforts by cutting down marine fuel consumption and consequently reducing CO2 and other Greenhouse Gas Emissions (GHG). Due to climate change both the European Union (EU) and the International Maritime Organization (IMO) are analysing the inclusion of international shipping in the EU Emissions Trading System (ETS) in the near future or alternatively implementing a carbon tax. The paper proposes a methodology to decide the optimal speed of a vessel taking into account its characteristics and the factors that determine its economic results. The calculated cash flow can be used in valuation models. The methodology is applied for a case study for any container ship in a range from 2000 to 20,000 Twenty-foot Equivalent Units (TEU) on a leg of a round trip from Shanghai to Rotterdam. We calculate how speed reduction, CO2 emissions and ship owner’s earnings per year may vary between a business-as-usual scenario and a scenario in which shipping is included in the ETS. The analysis reveals that the optimal speed varies with the size of the vessel and depends on several variables such as marine fuel prices, cargo freight rates and other voyage costs. Results show that the highest optimal speed is in the range of 5500–13,000 TEUs whether or not the ETS is applied. As the number of TEUs transported in a vessel increases emissions per TEU decrease. In an established freight rate market, the optimal speed fluctuates by 1.8 knots. Finally, the medium- and long-term expectations for slow steaming are analysed based on future market prices.This research is supported by the Basque Government through the BERC 2018–2021 programme and by the Spanish Ministry of Economy and Competitiveness (MINECO) through BC3 María de Maeztu excellence accreditation MDM-2017-0714. Further support is provided by the project MINECO RTI 2018-093352-B-I00

Powering newly constructed vessels to comply with ECA regulations under fuel market prices uncertainty: Diesel or dual fuel engine?

Over the last decade, marine engine engineering has evolved considerably, to the point where engine technology can be considered mature and reliable using LNG as fuel without affecting safety at sea. This paper analyses the choice between diesel or dual engines jointly and considers the alternatives of installing or not installing a sulphur scrubber when building a new vessel. The dual engine is more flexible because it can consume liquefied natural gas (LNG) as other marine fuels but the initial investment is more expensive. On the other hand, the use of scrubbers enables the use of marine fuels with high sulphur content in Emission Control Areas (ECAs), these marine fuels are usually cheaper also we consider Selective Catalytic Reduction technology (SCR) in all cases to minimize NOx. The paper calibrates a stochastic model for LNG and determines four marine fuel correlated prices. The work also considers a possible regulatory change from a non ECA to an ECA in the future. When we aggregate the installation costs to the present value of the expected combustible cost under uncertainty we can select the cheapest alternative. We obtain a minimum of expected present value of investment and fuels cost of 25.62 million US$ with a Dual engine with scrubber configuration. Our work shows that, in the cases considered, the use of a dual engine is the best alternative minimizing the total of investment and fuel costs. Finally, we analyse the distribution of fuel cost and its associated risks. © 2018 Elsevier LtdThis research is supported by the Basque Government through the BERC 2018-2021 program and by Spanish Ministry of Economy and Competitiveness MINECO through BC3 María de Maeztu excellence accreditation MDM-2017-0714. Additionally Luis M. Abadie is grateful for financial support received from the Basque Government via project GIC12/177-IT-399-13 and the Spanish Ministry of Science and Innovation via project ( ECO2015-68023 ).Basque Government, Spanish Ministry of Science and Innovation, Spanish Ministry of Economy and Competitiveness MINEC

Nola aurre egin itsas garraioak eragindako klima-aldaketari? Estrategia berriak

Currently maritime transport is growing due to globalization and economic growth, and it transports approximately the 90% of the world’s goods. World maritime transport fleet is increasing in amount and in size of vessels and, accordingly, marine fuel oil consumption is also increasing. The marine fuel oil consumption represents the 50% of the operational costs of a vessel and it has a huge environmental impact (ocean acidification, pollution, greenhouse effect, climate change…). Consequently, IMO (International Maritime Organization) created a specific environmental regulation and divided the ocean in different ECA zones (Emission Control Areas). The present work analyses the best strategy, a shipowner should adopt, to comply with ECA regulations, in three different panoramas: i) using an active vessel, placing a scrubber or consuming low sulphur marine fuel oil; ii) constructing a new vessel, choosing between marine dual engine or marine diesel mengine in both cases with or without scrubber; and iii) in case new ECA zones are created, which affects directly the vessel’s operational area.; Gaur egun, itsas garraioak munduko ondasunen % 90 mugitzen du. Ekonomiaren hazkundea eta globalizazioa direla-eta, garraio mota hori goraka doa. Munduko garraioontzi flotaren kopurua haziz doan neurrian, fuel-olioaren kontsumoa ere hazten ari da. Fuel-olioaren kostua garraio-ontzi baten kostu operazionalen % 50 baino gehiago da, eta erregai horren erabilerak eragin nabarmena du ingurumenean (azidifikazioa, kutsadura, berotegi-efektua…); hori kontuan izanik, ECA direlako guneetan (Emission Control Areas) banatu ditu munduko itsasoak IMOk (International Maritime Organization), ingurumen-legedi berezi baten pean. Artikulu honetan, aztergai da zer estrategia jarraitu behar duen armadore batek (itsasontzi baten ustiatzaileak) lege sorta horietara egokitzeko, honako hiru aldagai hauek kontutan izanda: i) eraikita dagoen itsasontzi bat ustiatzen badu, sufre gutxiagoko fuelak erabiltzea edo itsasontziaren motorra egokitzea; ii) itsasontzi berri bat eraikitzera badoa, motor duala edo diesel-motorra jartzea; eta iii) zer aukera dagoen IMOk ECA gune berriak sortzeko

Microlensing in H1413+117 : disentangling line profile emission and absorption in a broad absorption line quasar

On the basis of 16 years of spectroscopic observations of the four components of the gravitationally lensed broad absorption line (BAL) quasar H1413+117, covering the ultraviolet to visible rest-frame spectral range, we analyze the spectral differences observed in the P Cygni-type line profiles and have used the microlensing effect to derive new clues to the BAL profile formation. We confirm that the spectral differences observed in component D can be attributed to a microlensing effect lasting at least a decade. We show that microlensing magnifies the continuum source in image D, leaving the emission line region essentially unaffected. We interpret the differences seen in the absorption profiles of component D as the result of an emission line superimposed onto a nearly black absorption profile. We also find that the continuum source and a part of the broad emission line region are likely de-magnified in component C, while components A and B are not affected by microlensing. We show that microlensing of the continuum source in component D has a chromatic dependence compatible with the thermal continuum emission of a standard Shakura-Sunyaev accretion disk. Using a simple decomposition method to separate the part of the line profiles affected by microlensing and coming from a compact region from the part unaffected by this effect and coming from a larger region, we disentangle the true absorption line profiles from the true emission line profiles. The extracted emission line profiles appear double-peaked, suggesting that the emission is occulted by a strong absorber, narrower in velocity than the full absorption profile, and emitting little by itself. We propose that the outflow around H1413+117 is constituted by a high-velocity polar flow and a denser, lower velocity disk seen nearly edge-on.Comment: Accepted for publication in Astronomy and Astrophysic

Estimating the Volatility of Flights and Risk of Saturation of Airspaces in the European Core Area: A Methodological Proposal

Despite having some fluctuations and the impact of the COVID-19 crisis, the demand for flights had a general growing trend for the past years. As the airspace is limited, efforts to better manage the total number of flights are noteworthy. In addition, volatility (i.e., unpredicted changes) in the number of flights has been observed to be increasing. Efforts to improve flight forecasting are thus necessary to improve air traffic efficiency and reduce costs. In this study, volatility in the number of flights is estimated based on past trends, and the outcomes are used to project future levels. This enables risk situations such as having to manage unexpectedly high numbers of flights to be predicted. The methodological approach analyses the Functional Airspace Block of Central Europe (FABEC). Based on the number of flights for 2015–2019, the following are calculated: historic mean, variance, volatility, 95th percentile, flights per hour and flights per day of the week in different time zones in six countries. Due to the nature of air traffic and the overdispersion observed, this study uses counting data models such as negative binomial regressions. This makes it possible to calculate risk measures including expected shortfall (ES) and value at risk (VaR), showing for each hour that the number of flights can exceed planned levels by a certain number. The study finds that in Germany and Belgium at 13:00 h there is a 5% worst-case possibility of having averages of 683 and 246 flights, respectively. The method proposed is useful for planning under uncertainties. It is conducive to efficient airspace management, so risk indicators help Air Navigation Service Providers (ANSPs) to plan for low-probability situations in which there may be large numbers of flights