Seasonal Energy Storage Research Articles

Do We Really Need a Seasonal Energy Storage? Results for Photovoltaic Technology in an Unfavourable Scenario

Do We Really Need a Seasonal Energy Storage? Results for Photovoltaic Technology in an Unfavourable Scenario

SNG based energy storage systems with subsurface CO2storage

Power-to-gas-to-power technologies incorporating electrolysis, methanation, SNG-fired Allam cycles and subsurface storages allow for a confined and circular use of CO2/CH4and thus an emission-free seasonal storage of intermittent renewable energy.

Dynamic Exergy and Economic Assessment of the Implementation of Seasonal Underground Thermal Energy Storage in Existing Solar District Heating

Dynamic Exergy and Economic Assessment of the Implementation of Seasonal Underground Thermal Energy Storage in Existing Solar District Heating

Case study on optimal design and operation of detached house energy system: Solar, battery, and ground source heat pump

Government policy impacts the level of sustainability for which houseowners design and operate their energy system. Consequently, there is a need to consider the sustainability level resulting from different policies, assuming optimal design and operation. The present work focuses on detached residential houses, where the energy system consists of photovoltaic systems for energy generation and batteries and optional ground-source heat pump systems for energy storage. A mixed-integer linear programming model is presented, which takes policies and other constraints into account when optimizing system size and operation. The results allow overall sustainability validation through parameters like self-sufficiency and self-sustainability, as well as a detailed drill-down of the optimal operation. From the analysis, two modes of ground-source heat pump usage are seen. With a feed-in tariff present, its main use is as an energy source, while without this tariff the optimal use is for seasonal energy storage. It is also found that ground-source heat pump systems contribute to increased sustainability, but they may not be economically beneficial for single-family homes having low or medium heating requirements. Demands for heating and cooling change with time and place, as do available area for photovoltaic energy generation and externally available energy sources. Therefore, a detailed analysis of the kind presented here is recommended before new energy policies are implemented. For each specific house or project, this kind of analysis will also be useful to evaluate the sensitivity of an energy system’s performance towards changing policies.

Hydrogen is Essential for Industry and Transportation Decarbonization

Hydrogen will play a critical role in a future comprehensive energy portfolio; hydrogen will be the decarbonizing tie between the different energy production sources and their end uses. Hydrogen acts as a zero-carbon energy carrier to couple energy sources and end uses. This provides the methodology to decarbonize the major energy consumption sectors of (1) the electric grid, (2) transportation and (3) industrial processes. It can provide energy storage supporting intermittent renewable power and cost-effective energy resilience; it enables the massive and seasonal energy storage that is required for a zero-emissions electric grid. It can be used in the transportation sector, especially for heavy-duty transportation where long ranges and fast refueling are critical. Renewable hydrogen is critical to decarbonize industrial processes that have needs for high temperature, chemical reduction and refining and chemical feedstocks. Hydrogen is potentially the only viable method to decarbonize all sectors of the economy simultaneously.

Optimal integration of Power-to-X plants in a future European energy system and the resulting dynamic requirements

The technologies for future energy systems must be developed now, but they will be deployed into energy systems very different from those of today. This is a challenge for Power-to-X technologies, which rely on the fluctuating production of renewable energies. Dynamic analysis is indispensable to achieve ideal integration of Power–to–X into the energy system. Thereby dynamic requirements for Power-to-X plants become clear and can be fed back to plant operators and component manufacturers. This allows to develop key components of Power-to-X today in a way that they match future energy systems perfectly. Using linear programming, this study optimizes a large-scale energy system completely coupled with the components of a Power-to-X plant. This Power-to-X plant produces hydrogen and synthetic natural gas. The results reveal that in the considered scenario Power-to-X plants are installed in almost all regions and are used for multi-day to seasonal energy storage. Electrolysis must be operated very dynamically and has about 200 starts a year in every region, whereas methanation is much more decoupled from the fluctuations of renewables and only has about 40 starts a year in every region. This is made possible by a hydrogen storage system which, if ideally designed, can store the hydrogen production of the electrolysis for an average of 17 h. Furthermore, this study investigates other flexibility requirements for Power-to-X plants including their scheduling, full load hours, average uptimes, and average downtimes.

Electrical energy storage using compressed gas in depleted hydraulically fractured wells

SummaryRenewable forms of electricity generation like solar and wind require low-cost energy storage solutions to meet climate change deployment goals. Here, we explore the use of depleted hydraulically fractured (“fracked”) oil and gas wells to store electrical energy in the form of compressed natural gas to be released to spin an expander/generator when electrical demand is high. Our reservoir model indicates that the same dual-porosity geological environment of fracked wells used to liberate hydrocarbons is also suitable for storing and releasing gas in a diurnal or seasonal cycle. Round-trip storage efficiency is calculated to be 40%–70% depending on the natural reservoir temperature. Levelized cost of storage is estimated to be $70–270/MWh, on par with pumped hydro storage. This study indicates that repurposed “fracked” wells could provide a much-needed low-cost seasonal energy storage solution at the TWh scale.

Long-duration energy storage for reliable renewable electricity: The realistic possibilities

ABSTRACT Several American states mandate zero-carbon electricity systems based primarily on renewable technologies such as wind and solar power. Reliable and affordable electricity systems based on these variable resources may depend on the ability to store large quantities of low-cost energy over long timescales. Long-duration storage technologies (that is, those that provide from 10 to hundreds of hours of storage) have much cheaper energy storage capital costs than lithium-ion batteries. Long-duration storage plays unique roles, such as seasonal and multi-year storage, that increase the affordability of electricity from variable renewable energy. We compare realistic options for seasonal energy storage, including underground hydrogen, pumped hydro, pumped thermal, and compressed air systems. To make 100 percent renewable electricity reliable and more affordable, such long-duration storage technologies can be employed.

Sustainable energy supply for self-sufficient buildings with seasonal energy storages – parametric study

To reduce greenhouse gas emissions, the efficiency of energy supply systems must be increased, for example, using renewable energy sources. Since the generation of renewable energy can depend on weather conditions and other parameters, the use of short- or long-term energy storage enables an increase in the covered building energy demand. Due to the large number of available technologies for renewable energy generation and storage, it is possible to combine these systems into different energy supply concepts. By optimizing and comparing the designed concepts, the most suitable one can be determined with respect to the current and future investments. A comprehensive comparison of energy supply concepts must include both economic and energy evaluation criteria. This study focuses on parametric numerical simulations to identify economically feasible and sustainable energy supply concepts for a practical case of new residential buildings. The results show that electrical storage and on-site power generation can provide the greatest benefits. In contrast, large thermal storage systems are not economically viable.

Prospective life-cycle assessment of greenhouse gas emissions of electricity-based mobility options

Electricity-based mobility (EBM) refers to vehicles that use electricity as their primary energy source either directly such as Battery Electric Vehicles (BEV) or indirectly such as hydrogen (H2) driven Fuel Cell Electric Vehicles (FCEV) or Synthetic Natural Gas Vehicles (SNG-V). If low-carbon electricity is used, EBM has the potential to be more sustainable than conventional fossil-fuel based vehicles. While BEV feature the highest tank-to-wheel efficiency, electricity can only be stored for short durations in the energy system (e.g. via pumped-hydro storage or batteries), whereas H2-FCEV and SNG-V have a lower tank-to-wheel efficiency due to additional conversion losses, H2 and SNG can be stored longer in pressurized tanks or the natural gas grid. Thus, they feature more flexibility with regard to exploiting renewable electricity via seasonal storage. In this study, we examine whether and under what circumstances this additional flexibility of H2 and SNG can be used to offset additional losses in the powertrain and conversion with respect to greenhouse gas (GHG) mitigation of EBM from a life-cycle point of view in a Swiss scenario setting. To this end, a supply chain model for EBM fuels is established in the context of an evolving Swiss and European electricity system along with an approach to estimate the penetration of EBM in a legislation compliant future passenger cars fleet. We show that EBM results in significantly lower life-cycle GHG emissions than a corresponding fossil fuels driven fleet. BEV generally entail the lowest GHG emissions if flexibility options can be offered through sector coupling, short-term and seasonal energy storage or demand side management. Otherwise, in particular with a large expansion of photovoltaics (PV) and curtailment of excess electricity, H2-FCEV and SNG-V feature equal or – in case of high-carbon electricity imports – even lower GHG emissions than BEV.

Reactor Development for Electrifying Bio-Methanation

Electrification of chemical conversions using renewable energy facilitates carbon neutral routes for synthesis of valuable products. These conversions can be used as a combined solution for CO2 conversion and energy storage. An emerging example is electrifying biocatalytic upgrading of CO2 to produce renewable natural gas for seasonal energy storage applications. To gain advantages of biological catalysis such as higher efficiency, selectivity and mild operation conditions in industrial applications, the key challenge is the poor productivity.To improve the reaction rates and biocompatible operation, we developed reactors with additively manufactures reactor components. Additively manufactured 3D electrodes facilitate higher volumetric productivity due to improved local surface properties.1 Transport issues could be minimized in electrolyte circulating bioreactors compared to static H-cells and stable performance over 2 months with pipeline-quality methane (>97% CH4) from CO2 could be demonstrated. Reference Kracke, J. S. Deutzmann, B. S. Jayathilake, S. Chandrasekaran, S. H. Pang, S. E. Baker and A. M. Spormann, Front. Microbiol. 12:696473

Demand Side Management Based Power-to-Heat and Power-to-Gas Optimization Strategies for PV and Wind Self-Consumption in a Residential Building Cluster

The volatility of renewable energy sources (RES) poses a growing problem for operation of electricity grids. In contrary, the necessary decarbonisation of sectors such as heat supply and transport requires a rapid expansion of RES. Load management in the context of power-to-heat systems can help to simultaneously couple the electricity and heat sectors and stabilise the electricity grid, thus enabling a higher share of RES. In addition power-to-hydrogen offers the possibility of long-term energy storage options. Within this work, we present a novel optimization approach for heat pump operation with the aim to counteract the volatility and enable a higher usage of RES. For this purpose, a detailed simulation model of buildings and their energy supply systems is created, calibrated and validated based on a plus energy settlement. Subsequently, the potential of optimized operation is determined with regard to PV and small wind turbine self-consumption. In addition, the potential of seasonal hydrogen storage is examined. The results show, that on a daily basis a 33% reduction of electricity demand from grid is possible. However, the average optimization potential is reduced significantly by prediction inaccuracy. The addition of a hydrogen system for seasonal energy storage basically eliminates the carbon dioxide emissions of the cluster. However, this comes at high carbon dioxide prevention costs of 1.76€kg−1.

Power-to-Gas and Power-to-X—The History and Results of Developing a New Storage Concept

Germany’s energy transition, known as ‘Energiewende’, was always very progressive. However, it came technically to a halt at the question of large-scale, seasonal energy storage for wind and solar, which was not available. At the end of the 2000s, we combined our knowledge of both electrical and process engineering, imitated nature by copying photosynthesis and developed Power-to-Gas by combining water electrolysis with CO2-methanation to convert water and CO2 together with wind and solar power to synthetic natural gas. Storing green energy by coupling the electricity with the gas sector using its vast TWh-scale storage facility was the solution for the biggest energy problem of our time. This was the first concept that created the term ‘sector coupling’ or ‘sectoral integration’. We first implemented demo sites, presented our work in research, industry and ministries, and applied it in many macroeconomic studies. It was an initial idea that inspired others to rethink electricity as well as eFuels as an energy source and energy carrier. We developed the concept further to include Power-to-Liquid, Power-to-Chemicals and other ways to ‘convert’ electricity into molecules and climate-neutral feedstocks, and named it ‘Power-to-X’at the beginning of the 2010s.

Geochemical Changes Associated with High-Temperature Heat Storage at Intermediate Depth: Thermodynamic Equilibrium Models for the DeepStor Site in the Upper Rhine Graben, Germany

The campus of the Karlsruhe Institute of Technology (KIT) contains several waste heat streams. In an effort to reduce greenhouse gas emissions by optimizing thermal power consumption on the campus, researchers at the KIT are proposing a ‘DeepStor’ project, which will sequester waste heat from these streams in an underground reservoir during the summer months, when the heat is not required. The stored heat will then be reproduced in the winter, when the campus’s thermal power demand is much higher. This paper contains a preliminary geochemical risk assessment for the operation of this subsurface, seasonal geothermal energy storage system. We used equilibrium thermodynamics to determine the potential phases and extent of mineral scale formation in the plant’s surface infrastructure, and to identify possible precipitation, dissolution, and ion exchange reactions that may lead to formation damage in the reservoir. The reservoir in question is the Meletta Beds of the Upper Rhein Graben’s Froidefontaine Formation. We modeled scale- and formation damage-causing reactions during six months of injecting 140 °C fluid into the reservoir during the summer thermal storage season and six months of injecting 80 °C fluid during the winter thermal consumption season. Overall, we ran the models for 5 years. Anhydrite and calcite are expected mineral scales during the thermal storage season (summer). Quartz is the predicted scale-forming mineral during the thermal consumption period (winter). Within ~20 m of the wellbores, magnesium and iron are leached from biotite; calcium and magnesium are leached from dolomite; and sodium, aluminum, and silica are leached from albite. These reactions lead to a net increase in both porosity and permeability in the wellbore adjacent region. At a distance of ~20–75 m from the wellbores, the leached ions recombine with the reservoir rocks to form a variety of clays, i.e., saponite, minnesotaite, and daphnite. These alteration products lead to a net loss in porosity and permeability in this zone. After each thermal storage and production cycle, the reservoir shows a net retention of heat, suggesting that the operation of the proposed DeepStor project could successfully store heat, if the geochemical risks described in this paper can managed.

Renewable hydrogen and ammonia for combined heat and power systems in remote locations: Optimal design and scheduling

AbstractUsing hydrogen (H) and ammonia (NH) for renewable energy storage has the potential to enable economical power and heat supply with high renewable penetrations, especially in remote locations which are characterized by high energy costs. In this work we assess the economic competitiveness of renewable combined heat and power (CHP) systems in Mahaka HI, Nantucket MA, and Northwest Arctic Borough (NWAB) AK by optimally designing these systems for scenarios in which power and heat can be purchased over a range of historical energy prices as well as when 100% renewable supply is required. We use a combined optimal design and scheduling model which minimizes annualized net present cost by determining optimal technology selection and size simultaneously with optimal schedules for each period of a system operating horizon aggregated from full year hourly resolution data via a consecutive temporal clustering algorithm. We find that renewable generation meets at least 85% of power demands and 75% of heat demands under the lowest energy prices investigated. Higher conventional energy prices lead to increased renewable penetration which is facilitated by renewable NH as a seasonal energy storage medium, as are 100% renewable CHP systems. NH is used for power generation with heat cogeneration in all three locations, as well as directly for heating in NWAB. On an annual cost basis, NH‐enabled 100% renewable CHP is only 3% more expensive in Mahaka and NWAB than systems which can purchase energy at the lowest prices, while it is 15% more expensive in Nantucket.

Organic Rankine Cycle-Ground Source Heat Pump with Seasonal Energy Storage Based Micro-Cogeneration System in Cold Climates: The Case for Canada

In cold climatic regions such as those located across Canada, it is necessary to implement heating system technology that is ultra-efficient and that has near-zero rates of emissions. Such systems would satisfy consumers’ energy needs and also comply with environmental standards, especially because the systems would account for more than 80% of residential energy use. This paper investigates two complementary efficient systems that can support these heating systems; ground-source heat pumps (GSHPs) and organic Rankine cycle systems (ORCs). The study proposes to couple these two systems in a parallel configuration. A dynamic simulation model created in TRNSYS platform has been deployed to assess the performance of the combined ORC-GSHP based micro-cogeneration system. This former provides heating to a residential house during the heating mode as needed. It has the capacity to switch to a charging mode, during which the ORC system is directly coupled to the ground heat exchanger (GHE), which works as a thermal energy storage and supplies energy to the GSHP. The feasibility of this combined system arrangement, and its comparison with a conventional GSHP system are examined for use in residential buildings in three cities across the varied climatic regions within Canada, namely Edmonton (AB), Halifax (NS), and Vancouver (BC). Results showed that the proposed micro-cogeneration system recorded less energy use of over 80%. The addition of the ORC system had a definite effect on the performance of the GSHP in that it decreased the operating hours from 11–58% compared to the conventional GSHP case and maintained consistently higher COP values. These results may help to specify viable ORC-GSHP based micro-co/trigeneration systems in cold climatic applications and should be useful for prototype design and development.

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Influence of Climatic Conditions on Dynamic Performance of Solar Hybrid Heating and Cooling Systems Integrating Seasonal Borehole Thermal Energy Storages: Application to School Buildings in the Campania Region of Italy

In this paper 5 different case studies of solar hybrid heating and cooling networks serving 5 different school buildings assumed as representative of the 5 provinces of the Campania region (southern Italy) have been modelled, dynamically simulated and analyzed by means of the software TRNSYS over a 5-year period. The plants are based on the operation of solar thermal collectors coupled with a seasonal borehole thermal energy storage; the solar field is also integrated with photovoltaic panels coupled with an electric energy storage; a solar-powered adsorption system is used for covering the cooling requirements. Specific weather data files have been developed for each city based on 1-year in-situ hourly measurements to accurately take into account the influence of climatic conditions on systems’ performance; the effects of thermo-physical properties of underground associated to the different locations have also been taken into consideration according to measured data available in the literature. The proposed systems have been compared with conventional Italian heating and cooling plants from energy, environmental and economic points of view in order to assess the potential benefits, highlight the effects of both weather data and characteristics of underground as well as promote the diffusion of solar systems for Italian applications.

Experimental investigation of a ground-source heat pump system for greenhouse heating–cooling

Abstract One of the important heating criteria of a greenhouse in the Northern hemisphere countries is heat availability, particularly in the winter season. Among other heat storage types, seasonal soil-based energy storage performance is auspicious. However, the performance is affected by the length and depth of borehole pipes used, which are very expensive for growers. Therefore, this study investigates the performance of a shallow seasonal soil-based energy storage heat pump, in a greenhouse. Thick insulations were installed to reduce soil heat loss. The soil thermal imbalance ratio was calculated to know the thermal recovery resulted. Based on the results, the heat pump’s seasonal coefficient of performance (COP) heating and cooling varied between 1.48–2.97 and 1.20–3.45, respectively. The COPsys heating and cooling were observed to be 1.51 and 1.55, respectively. However, the system successfully maintained indoor temperature >16°C in other seasons, except for winter. Due to low brine input in winter, the average indoor temperature dropped to 11°C, indicating a thermal soil property problem. Moreover, the proposed system achieved soil thermal imbalance ratio of 32.76%.

Hydropower and seasonal pumped hydropower storage in the Indus basin:pros and cons

The Indus basin has a large hydropower untapped potential for electricity generation and to regulate the Indus river flow, which could reduce flooding events and provide water supply during drought periods. In this paper, a computational module is developed to localize potential sites for hydropower generation and seasonal pumped hydropower storage (SPHS). The levelized costs for hydropower generation in the basin with conventional dams are as low as 12 USD/MWh, the cost of energy storage is 1 USD/MWh. In case of SPHS plants, the cost of energy storage is 2 USD/MWh. It can be concluded that the conventional hydropower potential is, for the moment, less expensive than SPHS, but its potential in the Indus basin is limited to 26 GW with hydropower costs below 50 USD/MWh and its reservoirs have a short lifetime due to the high sedimentation rates of the basin. SPHS would be an interesting alternative to complement the hydropower potential adding long-term water and energy storage with fewer sediments, social and environmental impacts. Given that the region has the highest potential and lowest costs for SPHS in the world, it could become a major player on seasonal and pluri-annual energy storage in Asia and globally.