Centre for Renewable Energy Sources and Saving

The dwindling availability of agricultural land, caused by factors such as rapid population growth, urban expansion, and soil contamination, has significantly increased the pressure on food production. To address this challenge, cultivating non-food crops on contaminated land has emerged as a promising solution. This approach not only frees up fertile soil for food production but also mitigates human exposure to contaminants. This work aimed to examine the impact of soil contamination with Cd, Pb, Ni, and Zn on the growth, productivity, metal accumulation, and the tolerance of five lignocellulosic non-food crops: switchgrass (Panicum virgatum L.), biomass sorghum (Sorghum bicolor L. Moench), giant reed (Arundo donax L.), African fodder cane (Saccharum spontaneum L. spp. aegyptiacum Willd. Hackel), and miscanthus (Miscanthus × giganteus Greef et Deu.). A two-year pot experiment was conducted in Greece, Italy, and Portugal, following the same protocols and applying various levels of metals: Cd (0, 4, 8 mg kg−1), Pb and Zn (0, 450, 900 mg kg−1), and Ni (0, 110, 220 mg kg−1). The experimental design was completely randomized, with three replicates for each treatment. The results showed that switchgrass and sorghum generally maintained their height and productivity under Cd and Pb stress but were adversely affected by high Zn and Ni concentrations. Giant reed and African fodder cane showed reduced height and productivity at higher Ni and Zn levels. Miscanthus exhibited resilience in height but experienced productivity reductions only at the highest Zn concentration. Heavy metal uptake varied among crops, with switchgrass and sorghum showing high Cd and Pb uptake, while giant reed accumulated the most Cd and Zn. Miscanthus had the highest Ni accumulation. The tolerance indices indicated that switchgrass and sorghum were more tolerant to Cd and Zn at lower concentrations, whereas miscanthus had lower tolerance to Cd but a higher tolerance to Zn at higher concentrations. Giant reed and African fodder cane demonstrated stable tolerance across most heavy metals. Accumulation indices highlighted the effectiveness of switchgrass and sorghum in Cd and Pb uptake, while miscanthus excelled in Ni and Zn accumulation. The cluster analysis revealed similar responses to heavy metal stress between African fodder cane and giant reed, as well as between sorghum and miscanthus, with switchgrass displaying distinct behavior. Overall, the study highlights the differential tolerance and accumulation capacities of these crops, indicating the potential for phytoremediation applications and biomass production in heavy metal-contaminated soils.

This paper investigates the integration and validation of multi-energy systems within the H2020 ERIGrid 2.0 project, focusing on the deployment of the JaNDER software middleware and universal API (uAPI) to establish a robust, high-data-rate, and low-latency communication link between Research Infrastructures (RIs). The middleware facilitates seamless integration of RIs through specifically designed transport layers, while the uAPI provides a simplified and standardized interface to ease deployment. A motivating case study explores the provision of power-to-heat services in a local multi-energy district, involving laboratories in Denmark, Greece, Italy, the Netherlands, and Norway, and analyzing their impact on electrical and thermal networks. This paper not only demonstrates the practical application of Geographically Distributed Simulations and Hardware-in-the-Loop technologies but also highlights their effectiveness in enhancing system flexibility and managing grid dynamics under various operational scenarios.

(Double) Daylight Saving Time (DST/DDST) synchronizes human daily activities with sunlight hours, aiming to save energy. China implemented DST/DDST in 1986 and annulled it in 1991, which has not since been observed. This study aims to revisit the household lighting energy-saving potentials of DST/DDST implementation in six representative highly urbanized Chinese cities across different latitudes and within different climate zones, based on the electricity consumption behaviour of Chinese people in the 2020s. We constructed country-specific Multiple Linear Regression (MLR) analysis models interrelated with the local characteristic features of the DST/DDST in China, including latitude, age structure, industrial structure, get-up and bedtime schedules. The results showed the following: (1) Both DST and DDST can effectively reduce household lighting consumption in all the studied case cities, while DDST has a superior energy-saving potential; (2) Considering China-specific lifetime schedules, April to October is the most recommended duration for DST/DDST implementation; (3) Northern cities in China exhibit greater potential for energy savings in lighting than southern regions. (4) Cities with larger portions of primary industry have more household lighting-saving potential in China. Based on the obtained results, monthly data and separate statistical data on household lighting could help promote the precision of regression models.

Smart grids and intelligent energy systems play a pivotal role in fostering the sustainable advancement of our civilization. Over the past few decades, power systems, like many other sectors, have undergone a rapid digital transformation. This rapid development necessitates a proactive response from universities, research institutes, industry stakeholders in relation to educational programmes. Educators must rapidly adapt their curricula and teaching methodologies to effectively train the next generation of engineering professionals. While curriculum crafting for new educational programs is inherently challenging, another layer of complexity arises when research collaborations in large consortia are tasked with delivering high-quality education within a given project scope and time frame. This paper outlines a methodology for establishing an educational strategy for such research projects. This approach takes into account the available resources and expertise of the project participants, while embracing modern, learner-centric educational methodologies. It also ensures alignment with broader objectives or frameworks. Furthermore, the strategy incorporates a dynamic evaluation process that runs concurrently with the educational activities. Finally, the ERIGrid 2.0 H2020 project upon which the proposed methodology was developed, is presented as a case study.

The continuous trend for transportation electrification imposes modern and innovative solutions in terms of hybridization and energy harvesting in roadway infrastructures (e.g., highways, charging points etc.). In this context, piezoelectric energy harvesters have emerged as a promising solution (combined with small battery energy storage units), for suppling low-power wireless sensor networks, traffic lights and indicators. This paper presents a literature review regarding piezoelectric energy harvesting technology, focusing on road transportation applications. Piezoelectric element types, materials and characteristics, power conversion techniques and applications are comprehensively studied and discussed. In parallel, an experimental assessment is performed in laboratory scale (emulating realistic conditions) and on the road, under realistic conditions. Experimental measurements indicate the applicability and suitability of piezoelectric energy harvesting in roadways and transportation infrastructure.

This work presents the materials selection process, the design and the dimensioning process of a latent heat storage tank that works between a high temperature heat pump and an Organic Rankine Cycle unit. The selected heat storage material is the S117 Phase Change Material that has a melting point at 117°C matches the operational temperature of the system at approximately 120°C. The tank configuration is selected for optimised heat transfer process, resulted from practical experience of the project partners and it is described in details in the document. The simulation results from the Computational Fluid Dynamic study of the tank are also presented here. This work should be useful for engineers designing compact heat storage tanks for medium temperature applications.

Germination of castor seeds of seven dwarf hybrid genotypes, compared to a ‘Local’ genotype, selected from a Tunisian population by the University of Catania well adapted to the Mediterranean environment, were studied at six different temperatures (8, 12, 16, 25, 32, and 40 °C). The results indicate that the optimal temperature (25 °C) and near-optimal temperature (32 °C) are the best temperatures for ensuring castor germination (final germination percentage (FGP) ≥ 82.81%). Furthermore, these temperatures positively influenced the vigour index (VI) and the radicle elongation. At a temperature of 8 °C, no germination occurred, while temperatures of 12 and 40 °C negatively affected the seed germination, which, in some genotypes, was null or negligible (<21.25%). A temperature of 16 °C allowed good results to be reached for the FGP and the other considered parameters. Overall, the dwarf hybrids performed better at high temperatures than at low temperatures, thus, making them suitable for late sowings, with the exception of the genotype ‘C1020’, which resulted the best performance at 16 and 40 °C, being suitable for both early and late sowings. On the other hand, the ‘Local’ castor genotype, being the best-performing genotype at 12 and 16 °C, and the most tolerant to low temperature (base temperature (Tb) 12.1 °C), could be used in the early sowing in spring.

The decarbonisation policies for the EU building stock can improve living conditions, including thermal comfort and lower energy bills. However, these measures may impose financial burdens on low-income households, reducing their disposable income and exacerbating their vulnerability. The current study investigates the impact of decarbonisation policies on the EU’s building stock, with a specific focus on Minimum Energy Performance Standards (MEPS), the new Emissions Trading System (ETS2) for buildings, and the phase-out of fossil heating systems. By employing a linear, static latest version of Microsoft Excel (Microsoft 365)-based model and analyzing Eurostat data, this study quantifies the effects of these policies on energy consumption, costs, and necessary investments. Moreover, the study emphasizes their implications for low-income groups using vulnerability indicators. The findings demonstrate that a combination of MEPs, ETS2, and phasing out fossil heating systems effectively reduces energy consumption and costs across most countries. However, implementing ETS2 alone may lead to energy reduction and discomfort for low-income groups without addressing underlying demand-side issues. To address this, this study recommends the implementation of more ambitious MEPs or the provision of additional funding alongside ETS2. The phase-out of fossil fuel boilers emerges as the most cost-effective measure in the medium to long term. While MEPS and the phase-out of fossil fuel boilers improve living conditions, they also impose upfront cost burdens and reduce disposable income for low-income households. Therefore, high subsidy rates and supportive policies are necessary to ensure equitable access to investments. The main recommendations include (a) shifting financing to renewable heating systems for low-income households by 2025, addressing cost issues and policies favouring gas boilers; (b) implementing high-funding rate subsidies for energy efficiency in low-income households before 2025, with technical guidance; (c) prioritising the Energy Efficiency First principle in planning to avoid additional emissions or higher costs for low-income households; and (d) considering the energy behaviour of low-income groups in regulations, employing a combination of policies to achieve desired outcomes and ensure thermal comfort.

In view of the European Union’s strategy on hydrogen for decarbonization and buildings’ decarbonization targets, the use of hydrogen in buildings is expected in the future. Backup power in buildings is usually provided with diesel generators (DGs). In this study, the use of a hydrogen fuel cell (HFC) power supply backup system is studied. Its operation is compared to a DG and a techno-economic analysis of the latter’s replacement with an HFC is conducted by calculating relevant key performance indicators (KPIs). The developed approach is presented in a case study on a school building in Greece. Based on the school’s electricity loads, which are calculated with a dynamic energy simulation and power shortages scenarios, the backup system’s characteristics are defined, and the relevant KPIs are calculated. It was found that the HFC system can reduce the annual CO2 emissions by up to 400 kg and has a lower annual operation cost than a DG. However, due to its high investment cost, its levelized cost of electricity is higher, and the replacement of an existing DG is unviable in the current market situation. The techno-economic study reveals that subsidies of around 58–89% are required to foster the deployment of HFC backup systems in buildings.

The European building sector is responsible for approximately 40% of total energy consumption and for 36% of greenhouse gas emissions. Identifying technological solutions capable of reducing energy consumption and greenhouse gas emissions is one of the main objectives of the European Commission. Ground source heat pumps (GSHPs) are of particular interest for this purpose, promising a considerable reduction in greenhouse gas emissions of HVAC systems. This paper reports the results of the energetic analysis carried out within the EU research project GEO4CIVHIC about the performance of geothermal heat pumps working with low-GWP refrigerants as alternatives for R134a and R410A. The work has been carried out through computer simulations based on base and regenerative reverse cycles. Several heat sink and heat source temperature conditions have been considered in order to evaluate the GSHPs’ performance in the whole range of real conditions that can be found in Europe. Particular attention has been paid to the evaluation of compression isentropic efficiency and its influence on the overall cycle performance when dealing with steady-state heat pump simulations. To do so, five different scenarios of isentropic efficiency calculation have been studied and discussed.

Demand for sustainably produced biomass is expected to increase with the need to provide renewable commodities, improve resource security, and reduce greenhouse gas emissions in line with COP26 commitments. Studies have demonstrated additional environmental benefits of using perennial biomass crops (PBCs), when produced appropriately, as a feedstock for the growing bioeconomy, including utilisation for bioenergy (with or without carbon capture and storage). PBCs can potentially contribute to Common Agricultural Policy (CAP) (2023‐27) objectives provided they are carefully integrated into farming systems and landscapes. Despite significant research and development (R&D) investment over decades in herbaceous and coppiced woody PBCs, deployment has largely stagnated due to social, economic and policy uncertainties. This paper identifies the challenges in creating policies that are acceptable to all actors. Development will need to be informed by measurement, reporting and verification (MRV) of greenhouse gas emissions reductions and other environmental, economic and social metrics. It discusses interlinked issues that must be considered in the expansion of PBC production: i) available land; ii) yield potential; iii) integration into farming systems; iv) R&D requirements; v) utilisation options; and vi) market systems and the socio‐economic environment. It makes policy recommendations that would enable greater PBC deployment: 1) incentivise farmers and land managers through specific policy measures, including carbon pricing, to allocate their less productive and less profitable land for uses which deliver demonstrable greenhouse gas reductions; 2) enable GHG mitigation markets to develop and offer secure contracts for commercial developers of verifiable low carbon bioenergy and bio‐products; 3) support innovation in biomass utilisation value chains; and 4) continue long‐term, strategic R&D and education for positive environmental, economic and social sustainability impacts.

The DigiMon project aims to develop and demonstrate an affordable, flexible, societally embedded, and smart digital monitoring early warning system for any subsurface CO2 storage field. The societal embeddedness level (SEL) assessment is a novel methodology which provides insight into the societal requirements for technological innovation to be deployed. The SEL assessment framework was applied in four case studies, concerning CCS development in Norway, the Netherlands, Greece, and Germany. The resulting societal embeddedness levels of CCS, on a scale of 1–4, were SEL 3 in Norway with considerable progress towards level 4, followed by the Netherlands with SEL 2 with several initiatives towards offshore demonstration projects, and then by Greece and Germany with SEL 1. The outcomes of the SEL assessments show which societal requirements have been met in current CCS developments and which ones should be improved for CCS deployment. They also show that monitoring currently is a regulatory requirement as part of permitting procedures, while it may alleviate community concerns on safety, provided that it has certain attributes. The insights from the four national case studies are further used in the DigiMon project to develop the innovative societal embedded DigiMon monitoring system.

Energy transition in islands constitutes a major challenge. Apart from a necessity, it can also be a great opportunity for sustainable social and economic development. Toward this direction, a new, promising movement has emerged recently in Greek islands. Straight from the roots of the insular population, development of energy communities comes as the result of increased awareness of local people, raised also by the legacy of lighthouse projects and initiatives. Kythnos, Ikaria, Sifnos, Tilos, Agios Efstratios, Crete, and Chalki, are all islands that have embraced the implementation of successful, local-scale innovation projects and/or initiatives, generating meaningful results across different energy aspects and contributing to positive social change. Our study provides an overview of the broader energy transition aspects in Greek islands, discusses the impact of the afore-mentioned exemplary cases, and further elaborates on the model of energy communities. According to our analysis, leveraging on the experience of lighthouse projects and initiatives, and on the dynamics of the emerging energy community movement, could lead to increased social and economic benefits for the insular populations, to broad public acceptance, and to minimum environmental impacts for the islands' natural ecosystems.

Blue Energy (BE) is expected to play a strategic role in the energy transition of Europe, particularly toward the 2050 horizon. It refers to a set of Marine Energy Sources (MES), including offshore wind, waves, tides, marine currents, sea thermal energy, salinity gradients, and marine biomass, which are exploited by different BE technologies. Nevertheless, the implementation of integrated solutions to exploit MES in marine areas does not just concern technological issues; it requires inclusive planning practices considering different aspects regarding climate and environmental impacts, landscape compatibility, interference with other marine activities (such as shipping, fishing, and tourism), and social acceptance. A replicable BE planning framework has been developed based on interdisciplinary knowledge in three Mediterranean sites in Greece, Croatia, and Cyprus, under the scope of the Interreg Med BLUE DEAL project. It has been implemented by some interdisciplinary experts through a collaborative and iterative process of data elaboration, mapping, evaluation, and visualization. Results concern the localization of suitable sites to install BE plants and the estimation of potential energy production and avoided emissions in selected scenarios. Together with visual simulations, this study shows the potential effects of the implementation of BE in specific marine areas, with a special focus on the most promising offshore floating wind farms and wave energy converters (WECs), as basic information for participative design and stakeholder engagement initiatives, including public authorities, businesses, and citizens.

Interdisciplinary and transdisciplinary collaboration has become a common practice in technology development projects. Rarely, however, the integration (and translation) of knowledge from different disciplines and different societal contexts is reported in detail. In this article, we address this gap and present the inter- and transdisciplinary technology development in the international research project “DigiMon—Digital Monitoring of CO2 Storage Projects” that aims to develop a human-centered monitoring system. Based on interviews, surveys and stakeholder workshops in Norway, Greece, Germany and the Netherlands, we identify characteristics of CO2 storage monitoring systems that reflect the concerns and expectations of publics and stakeholders. We document the translation of social scientific findings into technical expertise for the design of a monitoring system. We discuss how the interdisciplinary and transdisciplinary process has affected the technology development. In outlining how this process was set up, carried out and validated, we are able to show a viable route for the meaningful incorporation of heterogeneous knowledge in complex energy infrastructures. Furthermore, we discuss the features of the project organization that made this comprehensive process possible. Thus, our results contribute to inter- and transdisciplinary research organization in general and to the development of methods for monitoring CO2 storage in particular.

Decarbonization of remote or isolated island communities represents a significant challenge nowadays. Nevertheless, the environmental, economic, and social benefits seek more attention. Lately, blue energy sources, particularly offshore wind power, are gaining momentum to take the lead in the energy transition process, simultaneously offering numerous benefits for local communities and potential investors. In this research, offshore wind power is considered the main driver of the energy transition for the case of the island of Crete. The energy systems’ development scenarios are developed using an energy planning model EnergyPLAN, starting from a reference model developed for the year 2017. Since the island was recently isolated without connections to the mainland grid, integrating renewable energy sources was a challenging task that led to poor energy potential exploitation. The decarbonization of the power generation sector by offshore and onshore wind and photovoltaics can only partially reduce the import dependence on fossil fuels. At the same time, more significant efforts are expected in the transport and industry sectors. With the operational interconnections, 300 MW of offshore wind capacities can be deployed, averaging annual electricity production of 1.17 TWh, satisfying around 70% of total electricity demand.