Renewable Energy and Energy Saving: Worldwide Research Trends

Energy is a very important resource for the development of the residential and industrial sectors, and it should be used with high efficiency, low environmental impact, and at the lowest possible cost [1]. Historically, economic development has been closely correlated with increased energy consumption and greenhouse gas emissions, leading to significant environmental impacts and heavy dependence on fossil energy sources [2].

Today, there is an increasing concern for the environment, especially regarding the already evident rise in the planet’s temperature. This circumstance has led to technological progress in the use of natural resources for energy and their availability to all productive sectors [3].

Energy saving, responsible energy consumption, and efficient use of energy sources are essential at all levels. The importance of energy saving and efficiency measures is manifested in the need to reduce the energy bill, restrict energy dependence on the outside world, and reduce the emission of Greenhouse Gases (GHG) and the purchase of emission rights in order to meet the commitments acquired with the ratification of the Kyoto Protocol. Energy efficiency, including residential, industrial, and municipal energy savings, is critical to meeting national energy and climate change targets set by countries around the world [4]. Energy efficiency remains the least-cost option for meeting national climate change commitments.

After several years of negotiations, UN member states agreed on a roadmap that would help leaders and governments meet the EU’s 2016–2030 goals, which include promoting sustainable development and environmental protection for all countries. The 2030 agenda for sustainable development is made up of 17 sustainable development goals and 169 priority action targets for the period 2016–2030, highlighting in the energy sector goal 7: Ensure access to affordable, secure, sustainable, and modern energy for all people.

The climate alert raised by the scientific community has led to CO₂ emissions becoming the main vector for the transformation of the energy sector by 2020–2050. The systematic and deep decarbonization of the energy system is the priority political horizon to be achieved in the 21st century. The landmark Paris Climate Change Agreement (2015) aims, at a minimum, to keep the global average temperature increase “well below 2 °C” this century compared to pre-industrial levels. Renewables, coupled with a rapid increase in energy efficiency, are the cornerstone of a viable climate solution [5,6]. There are a number of global policies to achieve these goals. As an example, the European Union is committed to achieving climate neutrality by 2050. Achieving this goal will require a transformation of European society and the European economy, which will have to be cost-effective, fair, and socially balanced [7]. In China, there has been strong growth in the renewable energy sector compared to the fossil fuel and nuclear energy sectors. China aims to achieve carbon neutrality by 2060 and peak emissions by 2030 [8,9].

Faced with the current situation, it is vital to propose actions to put aside production models based on fossil fuels and opt for more sustainable models based on the circular economy, energy saving, and renewable energy [10,11].

Energy saving and renewable energy allow us to save our scarce economic resources, postpone the depletion of our scarce fossil resources (on which our energy supply depends for the most part), and finally seem to be some of the best alternatives for reducing CO₂ emissions [4,12].

This Special Issue aims to advance the contribution of use of renewable energies and energy saving in order to achieve a more sustainable world. Leading authors have published important publications in the field of renewable energies and energy saving:

Abdelhakim Mesloub, Ghazy Abdullah Albaqawy, and Mohd Zin Kandar developed a study on the use of Building Integrated Photovoltaic windows under semi-arid climate in Algerian office buildings. This study was realized in terms of energy production, heating and cooling load, and artificial lighting. The results demonstrate the great advantages of the use of such windows in terms of energy savings compared to energy demand.

Walter Gil-González, Oscar Danilo Montoya, Luis Fernando Grisales-Noreña, Alberto-Jesús Perea-Moreno, and Quetzalcóatl Hernández-Escobedo developed an optimization model for the optimal placement and sizing of wind turbines, considering wind speed and demand curves and their reactive power capacity. The authors employed the General Algebraic Modeling System to develop the optimization model.

Van-Hai Bui, Akhtar Hussain, Thai-Thanh Nguyen, and Hak-Man Kim proposed a multi-objective stochastic optimization model to determine the set-point for a wind farm (WF) system.

Erika Winquist, Michiel Van Galen, Simon Zielonka, Pasi Rikkonen, Diti Oudendag, Lijun Zhou, and Auke Greijdanus analyzed how the biogas business will develop until 2030 in three countries (Germany, the Netherlands and Finland). This study is based on expert opinions.

Wai Fang Wong, AbdulLateef Olanrewaju, and Poh Im Lim evaluated the causal relationships between value factors and value outcomes of building maintenance in public hospitals in Malaysia. They concluded that value-adding practices and value co-creation have a positive influence on value outcomes in hospitals.

Andrés Alfonso Rosales-Muñoz, Luis Fernando Grisales-Noreña, Jhon Montano, Oscar Danilo Montoya, and Alberto-Jesus Perea-Moreno developed a methodology to optimize the power flow problem in direct current (DC) employing and optimization algorithm based on the multiverse (master stage) and the numerical method (slave stage) theories.

Artem Korzhenevych and Charles Kofi Owusu estimated the willingness to pay (WTP) values for renewable-generated electricity in five off-grid communities with a pilot renewable minigrid. The authors used data obtained from surveys of the inhabitants of these five communities.

Wai Fang Wong, AbdulLateef Olanrewaju and Poh Im Lim studied the critical success factors for improving the level of maintenance service delivery of hospitals. They conducted a total of 66 surveys among maintenance staff of public hospitals in Malaysia.

Vadim A. Golubev, Viktoria A. Verbnikova, Ilia A. Lopyrev, Daria D. Voznesenskaya, Rashid N. Alimov, Olga V. Novikova, and Evgenii A. Konnikov developed a model to study the evolution of non-conventional renewable energies over time, in order to guarantee their continuity and reliable and uninterrupted supply, taking into account the existing electricity system.

List of Contributions:

• Mesloub, A.; Albaqawy, G.A.; Kandar, M.Z. The Optimum Performance of Building Integrated Photovoltaic (BIPV) Windows Under a Semi-Arid Climate in Algerian Office Buildings.
• Gil-González, W.; Montoya, O.D.; Grisales-Noreña, L.F.; Perea-Moreno, A.-J.; Hernandez-Escobedo, Q. Optimal Placement and Sizing of Wind Generators in AC Grids Considering Reactive Power Capability and Wind Speed Curves.
• Bui, V.-H.; Hussain, A.; Nguyen, T.-T.; Kim, H.-M. Multi-Objective Stochastic Optimization for Determining Set-Point of Wind Farm System.
• Winquist, E.; Van Galen, M.; Zielonka, S.; Rikkonen, P.; Oudendag, D.; Zhou, L.; Greijdanus, A. Expert Views on the Future Development of Biogas Business Branch in Germany, The Netherlands, and Finland until 2030.
• Wong, W.F.; Olanrewaju, A.; Lim, P.I. Value-Based Building Maintenance Practices for Public Hospitals in Malaysia.
• Rosales-Muñoz, A.A.; Grisales-Noreña, L.F.; Montano, J.; Montoya, O.D.; Perea-Moreno, A.-J. Application of the Multiverse Optimization Method to Solve the Optimal Power Flow Problem in Direct Current Electrical Networks.
• Korzhenevych, A.; Owusu, C.K. Renewable Minigrid Electrification in Off-Grid Rural Ghana: Exploring Households Willingness to Pay.
• Wong, W.F.; Olanrewaju, A.; Lim, P.I. Importance and Performance of Value-Based Maintenance Practices in Hospital Buildings.
• Golubev, V.A.; Verbnikova, V.A.; Lopyrev, I.A.; Voznesenskaya, D.D.; Alimov, R.N.; Novikova, O.V.; Konnikov, E.A. Energy Evolution: Forecasting the Development of Non-Conventional Renewable Energy Sources and Their Impact on the Conventional Electricity System.