Energy storage in Spain: Forecasting electricity excess and assessment of power-to-gas potential up to 2050

Innovative technologies and strategies to decarbonize electricity generation, transport, and heat supply sector are key factors to achieve the global climate targets set by international organizations. One of these strategies implies a significant increase of the share of renewable electricity in the energy mix. Given the intermittent behaviour of renewable energy sources (RES), a detailed assessment of future energy scenarios is required to estimate the potential surplus in electricity production. To facilitate the penetration of renewable energy sources up to significant shares, massive long-term electricity storage technologies must be considered. Among these technologies, power-to-gas (PtG) systems may foster the fossil fuels switch by providing storage of surplus renewable electricity in the form of hydrogen or synthetic natural gas. Thus, this energy carrier could be reconverted to electrical power to cover peak demand periods. In this work, a study of the prospective Spanish scenario is presented and the potential of PtG technology is assessed in terms of expected renewable surplus. We found that the annual electricity surplus for 2050 might vary between 1.4 TWh and 13.5 TWh, and the required PtG capacity would be in the range 7.0–19.5 GW, depending on the renewable production pattern and the increment of demand

Power to gas-oxyfuel boiler hybrid systems

One of the main future energy challenges is the management of electrical supply and demand, mainly motivated by the increase of share renewable energy in electricity mix. Thus, energy storage represents a crucial line of research and innovative solutions are currently being proposed. Power to Gas is a technology which stores excess of electrical energy in form of synthetic natural gas through the methanation of hydrogen produced by electrolysis. Methanation requires a source of CO2 which could be provided from the flue gas of an oxyfuel boiler. A further advantage of this hybridization comes from the supply of the oxygen generated by electrolysis to the oxyfuel combustion. In this study the concept is simulated using Aspen Plus® software and the performance of the combined system is analysed through the definition of a size ratio, ¿¿¿¿, that relates the flow of renewable hydrogen produced in electrolyser and the thermal output of the boiler. This variable has allowed defining different ranges of operation for a PtG- oxycombustion hybridized plant. Thus, for ¿¿¿¿ of 1.33, the air separation unit required as an auxiliary element for the oxyfuel boiler becomes unnecessary while if this ratio is increased up to 2.29, flue gas is completely consumed in the methanation plant and converted to synthetic natural gas

Trabajando la demostración con profesorado de secundaria en formación

Trabajar la demostración en el aula es interesante no sólo por su importancia desde el punto de vista del quehacer matemático, sino por su contribución a la comprensión de los conceptos matemáticos involucrados (Hanna, 1995). Esta necesidad ha sido recogida de forma desigual en los distintos planes de estudios españoles desde 1934 (Ibañes & Ortega, 2002). La LOMCE establece el aprendizaje de la demostración como obligatorio y transversal a todos los contenidos. Sin embargo, los contenidos relativos a la demostración se presentan en forma de lista sin un orden lógico que ayude al profesor a planificar su enseñanza. Así, surge el interés de llevar a cabo actividades de formación de profesorado de secundaria relacionadas con la demostración, que involucren tanto aspectos relativos a la práctica de la demostración, como a su enseñanza y aprendizaje

Reducing cycling costs in coal fired power plants through power to hydrogen

The increase of renewable share in the energy generation mix makes necessary to increase the flexibility of the electricity market. Thus, fossil fuel thermal power plants have to adapt their electricity production to compensate these fluctuations. Operation at partial load means a significant loss of efficiency and important reduction of incomes from electricity sales in the fossil power plant. Among the energy storage technologies proposed to overcome these problems, Power to Gas (PtG) allows for the massive storage of surplus electricity in form of hydrogen or synthetic natural gas. In this work, the integration of a Power to Gas system (50 MWe) with fossil fuel thermal power plants (500 MWe) is proposed to reduce the minimum complaint load and avoid shutdowns. This concept allows a continuous operation of power plants during periods with low demand, avoiding the penalty cost of shutdown. The operation of the hybrid system has been modelled to calculate efficiencies, hydrogen and electricity production as a function of the load of the fossil fuel power plant. Results show that the utilisation of PtG diminishes the specific cost of producing electricity between a 20% and 50%, depending on the framework considered (hot, warm and cold start-up). The main contribution is the reduction of the shutdown penalties rather than the incomes from the sale of the hydrogen. At the light of the obtained results, the hybrid system may be implemented to increase the cost-effectiveness of existing fossil fuel power plants while adapting the energy mix to high shares of variable renewable electricity sources

Power to Gas projects review: Lab, pilot and demo plants for storing renewable energy and CO2

Power to Gas (PtG) processes have appeared in the last years as a long-term solution for renewable electricity surplus storage through methane production. These promising techniques will play a significant role in the future energy storage scenario since it addresses two crucial issues: electrical grid stability in scenarios with high share of renewable sources and decarbonisation of high energy density fuels for transportation. There is a large number of pathways for the transformation of energy from renewable sources into gaseous or liquid fuels through the combination with residual carbon dioxide. The high energy density of these synthetic fuels allows a share of the original renewable energy to be stored in the long-term. The first objective of this review is to thoroughly gather and classify all these energy storage techniques to define in a clear manner the framework which includes the Power to Gas technologies. Once the boundaries of these PtG processes have been evidenced, the second objective of the work is to detail worldwide existing projects which deal with this technology. Basic information such as main objectives, location and launching date is presented together with a qualitative description of the plant, technical data, budget and project partners. A timeline has been built for every project to be able of tracking the evolution of research lines of different companies and institutions

Power to Gas technology under Spanish Future Energy Scenario

Power to Gas (PtG) has been pointed out in the last years as a promising energy storage technology to smartly manage the renewable intermittent power generation that limits the operational flexibility of the network. In this work, we present a prospective study for the Spanish case, in which the implementation potential of PtG technology is evaluated in terms of the estimated renewable surpluses. We found that the annual surplus for the year 2050 would vary between 1.4 TWh and 5.2 TWh, and the PtG capacity required would be in the range 7.0 - 13.0 GW, depending on the renewable production pattern considered

Power to Gas-biomass oxycombustion hybrid system: Energy integration and potential applications

A promising hybridization which increases the chances of deployment of Power to Gas technology is found in the synergy with oxycombustion of biomass. This study assesses the efficiency of an energy integrated system under different sizes and potential applications. District heating and industrial processes are revealed as the most suitable potential applications for this hybrid technology. Global efficiency of the combined system may be increased through thermal energy integration. The relative increment of efficiency achieved for those designs which avoid the requirement of an air separation unit and for those which completely consumed the generated CO2, are 24.5% and 29.7% respectively. A 2 MWth district heating case study is also analysed, revealing that 81.2% of the total available heat from the PtG–oxy system could be integrated raising the global efficiency up to 78.7% at the adequate operational point. Further ‘full-fuel-cycle’ analysis will be required prior to decide the interest of the concept under a specific scenario in comparison to other available energy storage technologies

Working with patterns through chess-based problems. strategies and reasoning levels of primary school students.

The study of patterns has been recognised for many years as setting up the very essence of mathematics. Patterns are connected to all topics in mathematics, so this theme is present throughout the school mathematics curriculum. Among the large number of interesting examples for working on pattern search in elementary school using situations familiar to students, we chose chess because of the relationships shown between this game and different aspects of mathematics. The objectives were to determine the strategies and classify the students' levels of reasoning when working with patterns to solve chess-based problems. A sequence of activities was designed to carry out this task. The sequence presents visual and numerical patterns ordered progressively from a greater presence of visual aspects to a predominance of numerical aspects. The results of this work suggest that chess favours the use of a variety of strategies, some of them even different from those found in previous literature. Students rely on the geometry of the board when working with these particular types of patterns. However, the results show that the level of reasoning is higher in the case of solving numerical patterns

Power to gas-electrochemical industry hybrid systems: A case study

Several researchers have proposed in literature different Power to Gas (PtG) hybridizations to improve the efficiency of this energy storage technology. Some of the synergies of this hybrid systems are already being tested under real conditions (e.g. PtG-Amine scrubbing, PtG-wastewater treatment) while others have only been studied through numerical simulations (e.g., PtG-oxyfuel combustion). Here, a novel hybridization between Power to Gas and electrochemical industries is proposed for the first time. This PtG-Electrochemical hybridization avoids to implement the typical water electrolysis stage of PtG since hydrogen is already available in the plant. This study thoroughly analyzes the implementation of Power to Gas in a real electrochemical plant that sub-produces hydrogen from the lines of production of chlorate, chlorine, and potassium hydroxide. It is shown that the required carbon dioxide for methanation can be captured from the flue gas of the factory''s boilers without additional energy penalty thanks to energy integration. The methanation plant has been designed according to the H2 and CO2 availability, taking into account the number of operating hours and the degree of usage of by-products. Results show that this PtG hybridization could operate more than 6000 h per year at large scale concepts (nominal H2 inputs of 2000 m3/h (NTP)), which represents 2000 h more than pilot/commercial demonstrations of classic PtG concepts. Besides, a detailed economic analysis demonstrates the economic feasibility of the system under current scenarios. It is shown that the capital investment would be recovered in 8 years, generating a 4.8 M€ NPV at the end of the project lifetime. Thus, this work presents a suitable way to avoid the subsidy dependency that current PtG research projects have

Improved Flexibility and Economics of Combined Cycles by Power to Gas

Massive penetration of renewable energy in the energy systems is required to comply with existing CO2 regulations. Considering current power pools, large shares of renewable energy sources imply strong efficiency and economic penalties in fossil fuel power plants as they are mainly operated to regulate the system and constant shutdowns are expected. Under this framework, the integration of a combined cycle power plant (CCPP) with an energy storage technology such as power to gas (PtG) is proposed to virtually reduce its minimum complaint load through the diversion of instantaneous excess electricity. Power to gas produces hydrogen through water electrolysis, which is later combined with CO2 to produce methane. The main novelty of this study relies in the improved flexibility and economics of combined cycles by means of using power to gas as a tool to reduce the minimum complaint load. The principal objective of the study is the quantification of cost reduction under different scenarios of shutdowns and conventional start-ups. The case study analyses a combined cycle of 400 MWe gross power with a minimum complaint load of 30% that can be virtually reduced to 20% by means of a 40- MWe power-to-gas plant. Eight scenarios are defined to compare the reference case of conventional operation under hot, warm, and cold start-ups with power-to-gas-assisted operation. Additionally, PtG-assisted operation scenarios are analyzed with different loads (30–50–70%). These scenarios also include the consideration of a temporary peak of demand occurring in a period in which dispatch is below the minimum complaint load. Under this situation, the response time of conventional plants is very limited, while PtG-assisted CCPP can rapidly satisfy the peak. The techno-economic model quantifies the required fuel, gross and net power, and emissions as well as total costs and incomes under each scenario and net differential profit in an hourly basis. The analysis of the obtained results does not recommend the operation of the PtG-assisted CCPP at minimum complaint load for hot, warm, or cold start-ups. However, important marginal profits are achieved with the proposed system for part-loads operation over 50% for every sort of start-up, avoiding shutdowns and extending the capacity factor