**About the Editors**

**Mehreen Saleem Gul** is an Assistant Professor in Architectural Engineering in the School of Energy, Geoscience, Infrastructure and Society at Heriot-Watt University, Edinburgh. Mehreen's research experience is in environmental, engineering, and social issues associated with renewable and low-carbon technologies and sustainable buildings. She has developed her own outdoor research labs to investigate the performance of various photovoltaics including bifacial and the impact of ground albedo. Mehreen has over 34 peer-reviewed articles and is a contributor to the Chartered Institution of Building Services Engineers (CIBSE): Guide J, Weather, Solar and Illuminance data (2002) and Guide A, Environmental Design (2015). Mehreen was awarded the CIBSE Napier Shaw Bronze Medal for best paper on an entirely new approach for estimating solar diffuse irradiance.

**Eulalia Jadraque Gago** is a Professor at the University of Granada, in the Department of Civil Engineering Construction and Engineering Projects. She holds a Civil Engineering, MEng and PhD and has contributed to 23 international publications, and 4 chapters in books of prestigious publishers, such as CIBSE Guide A: Environmental design. Eulalia has over 15 international conferences and provided continued participation in investigation projects and contracts acting as a researcher. Eulalia has directed 1 thesis and has had managemen<sup>t</sup> charges at the University. Eulalia has been an invited researcher and professor at different universities. Since 2013, she has been a member of the World Society of Sustainable Energy Technologies

**Tariq Muneer** (Professor) is a Professor of Energy Engineering at Napier University, Edinburgh and currently chairs an active group engaged in research on 'Sustainable Energy' that includes 'Sustainable Transport'. Professor Muneer is an international authority on the subject of solar energy and its use in buildings with over 35 years of experience. He is the author of over 215 technical articles, most of which have been distilled in his research monographs.

## **Preface to "Development of Sustainable Energy: Generation Technologies and Concepts"**

The lack of access to energy supplies and transformation systems is a constraint to human and economic development. Achieving solutions to environmental problems that we face requires long-term potential actions for sustainable development. Sustainable energy generation should be widely encouraged, as it does not cause any harm to the environment and is widely available free of cost. Harnessing renewable energy resources appears to be one of the most efficient and effective solutions. Renewable energy sources such as solar, wind, geothermal, hydropower, biomass, and marine energy are at the centre of the transition to less carbon-intensive and more sustainable energy systems. The use of renewable energy through improved technologies and concepts is, therefore, expected to play a major role in the future of sustainable energy generation. Energy is central to nearly every major challenge and opportunity the world faces today. Be it for jobs, security, climate change, food production, or increasing incomes, access to energy for all is essential. The adoption of the new United Nations Sustainable Development Goals (SDGs) in 2015 marked a new level of political recognition of the importance of energy for development. For the first time, this included a target to ensure access to affordable, reliable, sustainable, and modern energy for all—collectively known as Sustainable Development Goal 7, or SDG 7. The aim is to enhance international cooperation by 2030 to facilitate access to clean energy research and technology, including renewable energy, energy efficiency, and advanced and cleaner fossil-fuel technology, and to promote investment in energy infrastructure and clean energy technology. The challenge is, however, far from being solved, and there needs to be more access to clean fuel and technology. Furthermore, more progress needs to be made regarding the integration of sustainable energy into end-use applications in sectors such as building, transport, and industry. This edition of the *Energies* journal addresses the barriers and challenges facing sustainable energy generation for future energy technologies and concepts and highlights potential solutions that should lead to sustainable development.

#### **Mehreen Saleem Gul, Eulalia Jadraque Gago, Tariq Muneer** *Editors*

#### *Article* **The Role of Low-Load Diesel in Improved Renewable Hosting Capacity within Isolated Power Systems**

#### **James Hamilton \*, Michael Negnevitsky, Xiaolin Wang and Evgenii Semshchikov**

Centre for Renewable Energy and Power Systems, School of Engineering, University of Tasmania, Hobart 7000, Australia; michael.negnevitsky@utas.edu.au (M.N.); xiaolin.wang@utas.edu.au (X.W.);

evgenii.semshchikov@utas.edu.au (E.S.)

**\*** Correspondence: james.hamilton@utas.edu.au; Tel.: +61-3-6226-2685

Received: 22 June 2020; Accepted: 28 July 2020; Published: 5 August 2020

**Abstract:** Isolated communities are progressively integrating renewable generation to reduce the societal, economic and ecological cost of diesel generation. Unfortunately, as renewable penetration and load variability increase, systems require greater diesel generation reserves, constraining renewable utilisation. Improved diesel generator flexibility can reduce the requirement for diesel reserves, allowing increased renewable hosting. Regrettably, it is uncommon for utilities to modify diesel generator control during the integration of renewable source generation. Identifying diesel generator flexibility and co-ordination as an essential component to optimising system hosting capacity, this paper investigates improved diesel generator flexibility and coordination via low-load diesel application. Case study comparisons for both high- and low-penetration hybrid diesel power systems are presented in King Island, Australia, and Moloka'i, Hawai'i, respectively. For King Island, the approach details a 50% reduction in storage requirement, while for Moloka'i the application supports a 27% increase in renewable hosting capacity.

**Keywords:** battery storage; hybrid power system; low-load diesel; microgrid; remote area
