The world’s economy is fuelled by energy. Depletion of resources and severe environmental effects resulting from the continuous use of fossil fuels has motivated an increasing amount of interest in renewable energy resources and the search for sustainable energy policies.

The changes required to progress from an economy mainly focused on hydrocarbons to one taking advantage of sustainable energy resources require considerable scientific research as well as the development of new engineering systems. Energy policies and management are of primary importance to achieve the development of sustainability and need to be consistent with recent advances in energy production and distribution.

In many cases, the challenges lie as much in the conversion from renewable energies (wind, solar, etc) to useful forms (electricity, heat, fuel) at an acceptable cost (including damage to the environment), as in the integration of those resources into an existing infrastructure.

The diverse topics covered by these papers involved collaboration between different disciplines in order to arrive at optimum solutions; including studies of materials, energy networks, new energy resources, storage solutions, waste to energy systems, smart grids and many others.

The Editors are especially grateful to the reviewers, as well as to the authors for their contributions.

The Editors

2017

Conventional district heating (DH) systems enable demand aggregation at district level and can provide high centralized heat generation performance values. However, thermal Renewable Energy Sources (RES) deployment at building level still remains low, and exploitation suboptimal, as it is limited by the instantaneous thermal load and storage capacity availability of each building. Buildings play the role of consumers that request a variable amount of heat over time and the thermal network the role of unidirectional heat supplier, without any smart interaction. The FP7 project A2PBEER has developed an innovative Smart Dual Thermal Network concept based on RES and Combined Heat and Power (CHP) as generation technologies, that enables transforming existing suboptimal DH systems, into integrated thermal networks with optimized performance and building level RES system production exploitation. It is based on an innovative Smart Dual Building Thermal Substation concept, which allows a bidirectional heat exchange of the buildings with the thermal network, and to aggregate district level distributed production and storage capacity (Virtual District Plant). With this approach buildings become prosumers maximizing decentralized RES production exploitation, as any possible local heat production surplus on any building of the district, will be delivered to the network to be used by other buildings. Additionally, this thermal network allows the delivery of the energy necessary to meet the heating and cooling demand of the buildings through a single hot water distribution network. In this way, it is possible to upgrade conventional DH systems to district heating and cooling systems, without the construction of a district cooling plant and a dedicated cooling distribution network. Cooling is produced at building level through sorption technologies using locally deployed solar collectors and the thermal network as energy sources. Finally, the district typologies and climatic conditions that maximize the potential of this thermal network concept have been identified.

Wind flow in urban environments could be seen as a potential source of energy. This form of energy could be exploited by means of micro wind turbines placed along the existing infrastructures. To test this, an outdoor campaign was organised, which recorded the wind characteristics at different locations around a highway noise barrier in Delft, the Netherlands. The real-time data set was validated with a two-dimensional Computational Fluid Dynamics study. Both the influence of the high turbulence and the inflow angle on the positioning of the micro wind turbines are assessed for the case of perpendicular flow towards the plane of the noise barrier. Results indicated that integrating micro wind turbines with the noise barriers proves advantageous due to the flow velocity increment downstream. Lastly, a noise assessment was conducted in order to determine the optimal spacing between micro wind turbines, which impacts its social acceptance.

Passive solar design can reduce building energy demand for heating, cooling and ventilation, while also contributing to the comfort, well-being and productivity of the building’s occupants. The successful application of passive solar features, such as solar walls, requires a good understanding of the factors influencing their energy performance and a correct assessment of this performance during the design process. This paper discusses some basic design strategies for successful application of solar walls and the factors with the most significant impact on their efficiency. It summarizes the principle results and findings of an experimental study, based on dynamic simulations and test site measurements. The energy performance of various configurations of unvented solar walls was investigated in different climatic conditions. The outcomes of the dynamic simulations were used to develop a simplified quasi-steady-state model, which can be used for approximate evaluation of the heat gains and heat losses through an unvented solar wall on a monthly basis. The model is compatible with the monthly method of EN ISO 13790.

Effective energy management involves making decisions that lead to the conservation of energy and the efficient use of resources for sustainable future. Kuwait Oil Company (KOC), a subsidiary of Kuwait Petroleum Corporation (KPC), is involved in exploration, drilling and production of oil and gas. KOC is fully committed towards energy management, energy efficiency and greenhouse gases (GHGs) emissions reduction, which may help in minimizing energy costs and mitigating environmental effects. In order to meet national and international standards ISO 50001 Energy Management System (EnMS), KOC undertaken a pilot study for developing an effective energy management program for KOC representative process units and main buildings. The objective of the program was to create an energy baseline and identify the potential improvement areas and provide inputs for the implementation of ISO50001 for certification. KOC has established the Energy Performance Indicators (EnPIs) for each of the process units and specific KPIs has been identified to monitor and control the energy performance. Furthermore, the study highlights the major achievements towards energy management, energy efficiency and greenhouse gas (GHGs) emissions reduction in order to help in minimizing energy costs and mitigating environmental effects.

The Mexican state of Baja California Sur has a high rate of population growth. It is also one of the states that are most vulnerable to climate change. Due to its location on the southern side of a roughly 900-mile long peninsula, and its natural separation from mainland Mexico, its power trans- mission networks are completely independent of the rest of the country. Thus, nearly all the energy used to generate electricity must be shipped to the state in the form of fossil fuels. The importation of energy supplies from the mainland results in higher costs for the state than in other areas of the country, causes greater environmental damage, and prevents a steady supply of energy to the state. This study’s objective is to propose a sustainable management model and to provide a reference to feasible sites available that could serve the Loreto region. An analytical model has been developed with multiple criteria and geographic information systems. This will allow for a wide range of spatial analysis of information covering the calculation of slopes, orientation, irradiation, infrastructure, etc. The municipal region of Loreto has roughly 288 square kilometres of land deemed suitable for the installation of solar plants. This area comprises 1.62% of the municipality. In 2016, the maximum electrical power demand for the entire state of Baja California Sur was 628 Megawatts per hour according to the Federal Electricity Commission (CFE). Loreto’s electrical capacity is currently 17MWh. Based on calculations that one photovoltaic plant located on two acres of land can produce one MWh, solar plants in the region could, theoretically, produce up to 14,403.35 MWh. Clearly, this potential capacity would be well above the demands of the municipality, which encompasses 3.8% of the state territory.

A great boom of hybrid vehicles has taken place on the automotive market in recent years, in particular, all these vehicles are now equipped with a continuously variable transmission (CVT) thanks to the use of a planetary gear train and two electric motor-generators.

The benefit provided by this system is the possibility to optimally control the engine velocity from an energy standpoint; in addition, drive comfort is increased thanks to the continuously variable transmission.

However, this is obtained at the cost of some amount of electrical losses in the components necessary to realize the above-mentioned structure.

This paper aims to evaluate the overall efficiency of this particular power train on different road missions; the same missions will be simulated at the same time for an identical hybrid vehicle equipped with a conventional transmission system.

In order to perform an energy analysis of the two architectures, one has to accurately address the main components generating energy losses: it will be thus presented the set of equations from which the mathematical stationary model of the CVT was obtained and how the different electric components and the internal combustion engine were modeled.

In addition, a brief description on the CVT optimization logic will be reported, the validity of this process will be then confirmed by comparing the ICE working points deriving from it and those declared by Toyota.

Finally, the fuel economy values coming from various road simulations will be compared in order to determine if or which hybrid architecture proves to be the most efficient one.

In this paper, the historical trends and future projections of whole of life CO₂ emissions is followed and includes the changing effects on embedded production energy as vehicles have been made lighter. Even so, the rapid reduction in fuel consumption of conventional vehicles leads to the ratio of embedded to in-use CO₂-e to have doubled in the last 30 years. This embedded energy sourced CO₂ recurs each time a new car is made, so the front end energy has to be amortised over the life of the vehicle. It is shown that the ratio is several times higher for battery electric vehicles, while hybrids fall between electric and conventional. The importance of vehicle useful life is emphasized. In the past, the optimum life to amortise the embedded energy was about 17 years but this depends on the prevailing rate of improvement in in-use energy of the marketed fleet. The paper concludes on the basis of the evidence presented that the optimum life for present conventional vehicles is between 10 and 12 years and for battery electric vehicles approaching 20 years with hybrids falling between. As the rate of annual fuel consumption improvement reduces from the present level of 5%/y, the desirable life-times of vehicles will increase. It is recommended that some form of government policy be implemented to achieve the changes in optimum vehicle life-time, over the next few decades, through support for ‘Cash for clunkers’ or equivalent mechanisms. This will enable the most rapid achievement of greenhouse gas emissions reduction. Incentives or other mechanisms need to be found to encourage hybrids rather than all electric vehicles to achieve best possible vehicle fleet CO₂ reduction.