This issue contains a selection of papers presented at the 2nd International Conference on Energy Production and Management in the 21st Century, “The Quest for Sustainable Energy”, organized by the Wessex Institute of Technology, UK, the Universitá Politecnica delle Marche, Italy, and the Ural Federal University, Russia.

The papers deal with many of the current issues related to energy production and management.

The quest for Energy can be seen as a unique long journey spanning over the history of humanity. As a matter of fact, humans have spent much of their lives struggling to achieve, gather, and manage energy.

In modern societies, the consumption of energy is one of the main indicators of the level of development. The rapid growth of the world population and the demand for higher living standards has led to the massive consumption of non-renewable energy sources with serious environmental consequences. While in the past many of these problems were localised, today we must talk of “global” pollution and the zone adversely affected is simply the whole world, mainly due to the extensive use of fossil fuels, and there is an urgent need to increase the use of renewable sources of energy.

Yet, the transition from an economy based on conventional energy to one relying on renewable sources represents a massive challenge. It requires new scientific and technological progress related not only to energy production but also to new ways of distribution, storage and usage, aiming to mitigate the negative environmental impacts associated with conventional energy. In this context, the complexity of modern energy production and management requires a multidisciplinary approach that can take into consideration not only advances in technology but also involves the environmental, economic, social and political aspects.

In such framework, the contributions in this issue present recent developments and experiences made in different parts of the world.

The digital version of the papers, as well as those resulting from the previous conference held in Ekaterinburg in 2014 are archived in Open Access format in the eLibrary of the Wessex Institute (witpress.com/elibrary) where they are freely available to the international community.

The Editors are grateful to all authors for the quality of their contributions as well as to the colleagues who helped to review the papers and hence ensure the quality of this issue.

The Editors Ancona, 2016

In the sectors of waste and biomass to energy, some debatable paradigms persist both among the spe- cialists and among the population, concerning the performances of a few energy options. The present article wants to give a contribution to clarify the debate related to three cases: (a) local impact of waste to energy plants, from conventional solutions to innovative ones (thermochemical processes); (b) local impact of Solid Recovered Fuel generation before energy exploitation; (c) local impact of combustion of wood. Three key articles have been selected from the Author’s production (more than one hundred Scopus indexed works) in order to perform a deeper analysis. Results demonstrate that, changing the perspective, some paradigms on the environmental performances of a few waste and biomass options for energy generation must be at least modified.

The scientific studies show that the greatest amount of CO2 emissions, in the European Union, results from the production of electricity and heat (for example, the production of coal-based energy in the EU Member States generates an amount of approximately one billion tons of CO2 emissions, that is about

1/4 of total CO2 emissions in the EU). The waste sector is a significant contributor to greenhouse gas

(GHG) emissions accountable for approximately one twentieth of the global greenhouse budget. This

contribution consists of CH4 emission from waste anaerobic decomposition and CO2 from thermal treatments. This study presents some district heating preliminary considerations through thermo-chem- ical conversion of renewable and non-renewable sources. Three locations are virtually analyzed, two

counties from Romania and one from Italy. A comparison is made between using different potential types of fuel: wood, coal, MSW, residual municipal solid waste (RMSW), bio-dried waste (BD) and solid-recovered fuel (SRF). The lower heating values (LHVs) of the two types of studied lignite (coal from Romania and Italy) are higher in comparison with the LHV of MSW, similar to the ones of RMSW and BD waste, but lower to the ones of SRF and wood, with some exceptions. Data suitable for preliminary global environmental balances and local impact considerations from atmospheric emis- sions were carried out for the quantity of primary fuel as presented. Results demonstrate that, even from the preliminary considerations, the environmental performances of district heating are strongly affected by the choice of the fuel.

Energy from biomass is becoming increasingly important as fossil fuel reserves diminish. The utiliza- tion of biomass is already prevalent in the domestic heating sector, but produces significant amounts of pollutants that are detrimental to human health. Dioxins, formed in any combustion process where car- bon, oxygen and, chlorine are present, are a subject of major interest due to their carcinogenicity. Much research has been carried out to study emissions from hazardous and municipal waste incinerators. Dioxin emission from wood combustion plants are also of interest, especially those due to combustion of treated, varnished or PVC-coated wood, which can produce high polychlorinated dibenzofurans (PCDD/F) emissions. This study compares the PCDD/F emissions produced by burning treated wood and virgin wood to verify if the differences are significant. Six different wood samples were analysed (three of treated wood and three of virgin wood) and a two-step wood gasification boiler was used. The analysis has been conducted both on off gas and on ashes. The measured PCDD/F concentrations are to be considered particularly limited and the treated wood use does not cause a general worsening in the PCDD/F emission. Thus, the wood treatment – subject of study – is not dangerous for PCDD/F. Finally, the experimental results indicated that during the thermal treatment, the formation mechanism of PCDD/F is the de novo synthesis.

Deep geologic injection of supercritical carbon dioxide (CO2) for enhanced oil recovery (EOR) has been widely used for improved oil recovery from depleted oilfields since early 1970s. The CO2 injec- tion maintains the pressure, mobilize the oil and release the petroleum resources that would otherwise be inaccessible. In addition to improving the oil recovery, the CO2-EOR contributes to minimize the impact of CO2-emissions to the atmosphere. The injected CO2 will be remained trapped in the under- ground geological formations, as the CO2 replace the oil and water in the pores. Carbonate reservoirs are characterized by low permeability and high heterogeneity, resulting in early breakthrough of gas and water and hence low oil recovery. The presence of naturally fractures in carbonate reservoirs is a major problem for the oil industry using CO2-EOR, because significant amount of CO2 are recycled to the well, and thereby not distributes in the reservoir. This study focuses on CO2 injection into a naturally fractured carbonate reservoir, including near-well simulations of CO2-distribution in the rock matrix. The simulations are carried out using the reservoir simulation software Rocx in combination with OLGA. The simulations show that CO2-injection into a naturally fractured carbonate reservoir in combination with closing of the fractured zones result in good distribution of CO2 in the reservoir.

Molten-salt reactors (MSRs) can provide inexpensive industrial process heating in addition to generat- ing electricity. In most cases, this can be best accomplished by design simplification, which results in improvements to MSR’s already existing and inherently strong safety characteristics. This is just one of a number of possible future scenarios that will influence the way in which MSR technology can develop and become marketable. The emphasis in this paper is to develop a reactor with application to the widest possible range of industries. This paper concentrates on the need to develop the inherent safety characteristics of the single fluid thermal reactor with the expectation that sufficient reliability and safety will be achieved in design so that these power generators will eventually be accepted for close integration into the fabric of modern society. It seems inevitable that the required licensing procedures needed for MSRs will vary considerably depending on their type because different designs vary so much. Those used for low-temperature process heat in addition to power generation require much less demanding regulatory procedures than those operating at higher temperatures. This is largely because long-term corrosion is more problematic at higher temperatures and present-day construction materials limit the development of MSRs from reaching their full potential. With appropriate experience with operating early designs of MSRs it is reasonable to expect that lower temperature versions will become certifiable for use in close proximity to a large range of human activities. Ultimately these reactors will be controllable remotely without the local attendance of technical staff.

Electric power is a necessity for the development of a society, without it would be impossible to see the world as we actually know. Its use is closely related to modern life and human development. Renewable energy is a good alternative for energy supply in regions where conventional power networks are absent or service quality is intermittent. The importance of these renewable energy sources lies in their lower emissions of carbon dioxide (CO2) to atmosphere and the reduced dependency on raw materials for importation and transport for power generation. Renewable energy is becoming economically competi- tive in the short to medium term. Hybrid power systems is a novel approach recently gaining popularity, since they combine multiple sources of renewable energy such as solar, wind, mini hydro-power, and also could include conventional generators as support. This combination allows the optimization of the power generation system by reducing emissions from the petroleum and coal based energy sources.

This paper presents a pilot hybrid power system design for the power supply in the hotel ‘La man- sion’ in the town of Acacias, Meta (Colombia). Simulation and optimization were based on a computer program known as HOGA educational version 2.2, which initially considered economic parameters associated to photovoltaic system such as: overall power, replacement cost and operation and main- tenance costs, as well as all powers to consider in the simulation. The main purpose is to present an alternative power source in the hotel located in an area with high rates of power outages, and gradu- ally include photovoltaic solar power combined with conventional energy supply, to meet the energy demand when the peak consumption periods occurs during power outages from the power grid.

This paper confirmed that hybrid power systems are a good energy supply alternative as auxiliary small power systems because they are capable of supplying the power demands during power grid out- ages or even in total absence of the power grid. Simulations showed that the combination of diesel and solar photovoltaics is a good alternative to meet lighting power demand in the hotel ‘La Mansion’, even in night hours thanks to the battery storage.

The paper presents the results of testing a 5 kW power plant based on solid oxide fuel cells (SOFC) with natural gas serving as fuel, equipped with a steam reformer combined with a burner. It includes a diagram of the power plant and a result analysis procedure based on heat and mass balances elaborated for the reformer, SOFC stack, catalytic burner and heat exchanger. The experimental findings were used to calculate the actual ratios of fuel utilization, oxygen consumption from cathode air in the elec- trochemical generator using two methods (heat and energy balances and Faraday’s law). A comparison of the results of the two methods revealed a small error, which was observed mainly in the second mode (60%).

Parameters of the power plant by ‘UIC’ LLC were reviewed at four steady running modes: 40% of SOFC’s power utilization (2 kW), 60% (3 kW), 90% (4.5 kW) and at the peak mode of 110% (5.4 kW), where the consumption exceeds the rated power by 10%.

Calculation of the equilibrium composition of conversion products, at temperatures (t3) reg- istered at the reformer’s outlet, allowed the formula for the natural gas reforming reaction to be obtained.

A simplified method of calculating the composition of the natural gas steam reforming products is described; the results are compared with calculations made in the program Gaseq, using the software package Mathcad for the solution of nonlinear equations.

Analysis of the results showed the effectiveness of a simplified method at temperatures above 800°C; in that temperature range, this method has an error of less than 0.5%, which is sufficient for using in practice.

The energy from biomass can be utilized through the thermochemical conversion processes of pyrolysis and gasification. Biomass such as wood chips is heated in a gasification reactor to produce a synthesis gas containing CO, H2 and CH4. The gas can be further processed to bioproducts or fuels. The thermo-

chemical process involves devolatilization of wood followed by steam gasification, CO2 gasification,

methanation, water gas shift reactions and methane reforming. To optimize the performance of the

reactor, it is important to study each of the reactions separately.

The reactions are simulated individually using the chemical process optimization software Aspen Plus. The results are compared with simulations performed with the Computational Particle Fluid Dynamic (CPFD) software Barracuda VR 15. The CPFD methodology solves the fluid and particle equations in three dimensions with the transient flow and is time-consuming. Aspen Plus is one dimen- sional and solves the included reactions fast.

The results of the Aspen Plus and CPFD simulations, given as product gas compositions (CO, CO2, CH4 and H2), show that each reaction contributes to the product gas composition differently. Com- parison between Aspen Plus and CPFD simulations of individual gasification reactions show good

agreement. However, when all reactions are included in the simulations, there is a deviation in the volume fraction of product gas composition.

A new 2-Parameter Rule Curve (patent pending) for Hydropower Generation takes into account the current state of the system, represented by the beginning-of-month reservoir level, in the selection of the end-of-month Rule Curve level/storage. Thus, the two decision parameters are current time and reservoir level. The Rule Curve aims to preserve the firm energy, and to generate as much secondary energy as possible; and is based on the maximum monthly value of a composite parameter related to the variation of the potential energy stored in the reservoir, calculated for every month in the backward simulation that gives the Firm Energy Yield of the reservoir-power plant system. The Rule Curve levels are calculated to give the required end-of-month level for each month as a function of the beginning-of-month level, can be represented in tabular (matrix) and graphical forms, and can be used alone or combined with the Rule Curve proposed by the USACE (1985 and 1989), whose only parameter is current time. The use of this new 2-Parameter Rule Curve for single reservoirs can increase the annual average/secondary energy output without reducing the firm energy, as tested by the simulation of several hydropower developments; the results show an increase of average/secondary energy when compared with the USACE Rule Curve. Energy increase depends on net head variability, regulating capacity of the reservoir and power-plant-rated capacity. A 50-year simulation of Grand Coulee Dam gives an average energy output of 22.6 TW-h/year year with the 2 -Parameter Rule Curve, and 20.9 TW-h/year with the USACE Rule Curve. The increase in average/secondary energy is 1.7 TW-h/yearr, due only to the change of the Rule Curve. Data published by the USBR indicates an average output of 21 TW-h/year for Grand Coulee Dam, which confirms the simulated results.

Two tandem wings undergoing two-dimensional sinusoidal and non-sinusoidal pitch and plunge motions are studied experimentally in a water channel at a chord-based Reynolds number of 10,000. The hindwing operates in the wake of the forewing, and its performance is affected by the vortices shed by the forewing in a tandem wing application. The vortex-wing and vortex-vortex interactions are affected by the changes in the phase angle between the fore and the hind wings. This study investigates how the changes in phase angle between the motions of the two wings play a role on the leading edge vortex (LEV) formations on the hindwing and the resulting effects on the power coefficient and the efficiency. The instantaneous lift and torque are measured by a force sensor; the velocity fields are captured by a digital particle image velocimetry (PIV) system. Sinusoidal and non-sinusoidal oscillations consisting of a pitch leading plunge motion with ϕ = 90° phase angle are used for the fore and hind wing motions. Different phase angles between the fore and hindwings are tested for the tandem configuration in the range of ψ = 0°–360° with an increment of 45°. The pitch pivot point to point distance of two chords was set between the fore and hindwings. It is found that the phase angle between the tandem foils determines the timing and the sign of the forewing-shed LEV when the hindwing encounters this LEV. Such an interaction affects the LEV formation, growth and shedding on the hindwing and results in a change in power generation performance of the hindwing. The results further show that at this specific distance between the wings, the maximum power coefficient and efficiency occur when the phase angle between the motions of the tandem wings is near ψ = 135° for the sinusoidal pitching and plunging.

The growing use of telecommunication technologies has led the industry to develop infrastructure to support this progress. The outer telecommunications cabinets are part of the Base Transceiver Station (BTS) allowing to accommodate and protect from outer adverse conditions, a set of electronic equipment needed to operate the mobile communication network. This kind of cabinets should have a proper thermal performance to ensure indoor air temperature below 55℃ to avoid exceeding the maximum operating temperature of the electronic equipment. This work describes the analysis of the thermal performance of an outdoor telecommunication cabinet (OTC) using the computational tool DesignBuilder. The simulation results are compared to the experimental data collected in real cabinet under normal operating conditions. The simulation results show that the air temperature predicted by the model is closer to the temperature measured experimentally inside the cabinet particularly when the weather data files of the computational model have a similar behavior to the actual weather data. Numerical studies show that the use of mechanical ventilation is effective in the extraction of heat generated inside the cabinet. However, there is a limit beyond which increasing the air flow rate does not result in a significant decrease of the cabinet air temperature. The studies also show the importance of the radiant properties and the geographical location of the cabinet. High values of the outer surface cabinet emissivity impair the thermal performance of the cabinet during the day and for some locations, an operational mechanical ventilation system may not be enough to maintain the indoor air temperature below 55℃. Overall, the use of DesignBuilder proved to be very effective for characterizing the thermal performance of telecommunications outdoor cabinets.

This work deals with the design of a standalone streetlight provided with a solar panel and a multiple vertical axis wind turbine (VAWT) along the structure. A prototype was built and is currently being tested in the Monte Dago campus of the Università Politecnica delle Marche. The ongoing focus of the project is to improve the overall efficiency and the manufacturing details for the industrialization. A battery bank allows delaying the energy delivering from the energy production, while a central process unit on board collects the data from every component in the equipment. This unit allows to monitor the day-by-day efficiency of the energy-lighting system, and to send the information wirelessly with the purpose of integrating into a smart grid-like management platform. The test site includes a meteorological mast, which can measure the weather conditions, such as wind speed and solar radiation. The wind turbines included in the streetlight have been studied from an aerodynamic point of view through an extensive experimental analysis in the wind tunnel. Moreover, the structural design of the wind rotors was carried out together with the security system including a mechanical brake, which prevents the damage of the components during high wind speed conditions. The control of the hybrid energy unit, designed to track the optimal performance, has been analyzed throughout the local wind conditions. Also, it is discussed the effectiveness of this streetlight concept in various climate situations.