Energy—History and Time Trends: Special Issue Editorial

1. Introduction

Energy is essential to human survival, and with increasing concerns regarding the global warming caused by greenhouse emissions, the energy field has become a global focal point. This calls for knowledge mobilization, which, to a large extent, can be achieved through learning the history of different energy sources. This Special Issue of Energies titled “Energy—History and Time Trends” aims to provide a platform for contributions on the history of energy, including time trends and comparisons. Both review papers with broad perspectives, such as the history of an energy source (global or for a certain region) or the entire energy sector for a certain region, were encouraged. Review articles with a narrower scope were also welcome, for example, investigations on certain projects or power plants of special historical value. Furthermore, research articles evaluating time trends for an energy source or a region were encouraged.

2. Contribution of Special Issue

In total, six articles were published in this Special Issue: three review articles and three research articles.

Table 1. The articles published in the 2021 Energies Special Issue “Energy―History and Time Trends”.

Title	Article Type	Reference
A Century of Use of SOLOMIT Thermal Insulation Panels	Review	[1]
A Brief History of the Kaplan Turbine Invention	Review	[2]
The Current Picture of the Transition to a Green Economy in the EU—Trends in Climate and Energy Policy versus State Security	Review	[3]
Forecasting and Assessment of the Energy Security Risk in Fuzzy Environment	Research	[4]
Assessing the Level of Renewable Energy Development in the European Union Member States. A 10-Year Perspective	Research	[5]
Improvement of AEP Predictions with Time for Swedish Wind Farms	Research	[6]

shows the titles and article types, and the reference list provides author and article details. The review articles include two historically in-depth studies of different technologies: the SOLOMIT thermal insulation panels [1] and the Kaplan turbine [2]. The third review article is a presentation of the historical progression of the changes and arguments indicating the need to move from fossil energy sources to the green economy within the European Union [3].

Partially using historical data, the research articles include a proposal for a new approach for assessing current and future energy security issues based on a complex security index and that is supported by the computationally transparent fuzzy multi-criteria decision analysis (MCDA) method [4]. The research articles also include two time-based assessments: the development of integration of renewable energy in the European Union [5] and the accuracy of AEP predictions for Swedish wind farms [6], the latter being a continuation of previously published work [7].

3. Discussion

The rapid development of energy systems is crucial to successfully limit global warming. However, it is still important to look in the rear-view mirror, so that future advances can be optimized through the use of previously gained experience. For this reason, studies focusing on the historical development of technologies as well as studies with more narrow scopes, such as technical threads, the development in countries, or even specific programs or power plants, are all valuable. For the example of wind power, studies of the developments that led to the commercial three-bladed horizontal axis wind turbines that are used today can be found in [8,9,10,11]; studies of technical threads other than the three-blade HAWT can be found in [12,13,14]; and the developments of specific countries or regions can be found in [15,16,17] and for different programs or even turbines can be found in [18,19].

Furthermore, sociotechnical studies are also of great importance for how to best understand which technical trends will become the most suitable and how they can be supported, such as through case studies of different countries or regions indicating how to best shape innovation systems for the development of renewable energy sources that focus on either technological development [20] or implementation [21]. Besides continuing to build the knowledge base of energy history, including knowledge of both successful and unsuccessful technologies or sub-technologies, that can be learned from, more integration between historical and sociotechnical studies could be advantageous for the future development of the energy field.