The use of direct current distribution systems in delivering scalable charging infrastructure for battery electric vehicles

The use of low voltage direct current (LVDC) distribution is becoming recognised as a technology enabler that can be used to efficiently network native DC generators with DC loads, offer improved power sharing capabilities, reduce power system material resource requirements and enhance the performance of variable speed machinery. Practical deployment opportunities for LVDC range from small-scale microgrids in the context of energy for development to sophisticated, modern building-level power distribution systems for commercial office spaces, manufacturing applications and industrial processes. However, the incumbent AC distribution system benefits from existing technical product and safety standards, which makes the early adoption of LVDC systems challenging from a risk and cost perspective. Concurrently, the demand for native DC loads such as Battery Electric Transportation Systems is growing. This is especially significant in the area of private electric vehicles (EVs), taxis and buses, but the prospect of electric trucks, ferries and shortrange aircraft are also tangible opportunities. The success of this electric transport revolution depends on several factors, one of which is the availability of battery charging infrastructure that can cost effectively integrate with the existing electrical network, deliver adequate energy transfer rates and adapt to the rapid technical development of this industry. This thesis explores the application of two, novel LVDC distribution systems for the development of scalable EV charging networks; where charging infrastructure has the ability to scale with increasing EV adoption and has a lower risk of becoming a stranded asset in the future. The modelling is supported by real, rapid DC charger utilisation data from the national charging network in Scotland, comprising over 192 chargers and 400,000 charging events. During the work of this thesis, it was found that a combined heat and power (CHP) system can economically support short duration charging scenarios by providing additional power capacity in a congested electrical grid. In this case the highest system efficiency and Net Present Value (NPV) is achieved with a fuel cell directly connected to the DC charging network, compared to other gas reciprocating CHP options. Furthermore, the proposition of a reconfigurable LVDC charging network, interfaced to the public AC distribution network, reduces the capital outlay, offers a higher NPV and improved scalability compared to other charging solutions. For charging system designers and operators, it was found that rapid DC chargers can be classified by specific locations, each possessing a distinct Gaussian arrival pattern and Gamma distribution for charging energy delivered.The use of low voltage direct current (LVDC) distribution is becoming recognised as a technology enabler that can be used to efficiently network native DC generators with DC loads, offer improved power sharing capabilities, reduce power system material resource requirements and enhance the performance of variable speed machinery. Practical deployment opportunities for LVDC range from small-scale microgrids in the context of energy for development to sophisticated, modern building-level power distribution systems for commercial office spaces, manufacturing applications and industrial processes. However, the incumbent AC distribution system benefits from existing technical product and safety standards, which makes the early adoption of LVDC systems challenging from a risk and cost perspective. Concurrently, the demand for native DC loads such as Battery Electric Transportation Systems is growing. This is especially significant in the area of private electric vehicles (EVs), taxis and buses, but the prospect of electric trucks, ferries and shortrange aircraft are also tangible opportunities. The success of this electric transport revolution depends on several factors, one of which is the availability of battery charging infrastructure that can cost effectively integrate with the existing electrical network, deliver adequate energy transfer rates and adapt to the rapid technical development of this industry. This thesis explores the application of two, novel LVDC distribution systems for the development of scalable EV charging networks; where charging infrastructure has the ability to scale with increasing EV adoption and has a lower risk of becoming a stranded asset in the future. The modelling is supported by real, rapid DC charger utilisation data from the national charging network in Scotland, comprising over 192 chargers and 400,000 charging events. During the work of this thesis, it was found that a combined heat and power (CHP) system can economically support short duration charging scenarios by providing additional power capacity in a congested electrical grid. In this case the highest system efficiency and Net Present Value (NPV) is achieved with a fuel cell directly connected to the DC charging network, compared to other gas reciprocating CHP options. Furthermore, the proposition of a reconfigurable LVDC charging network, interfaced to the public AC distribution network, reduces the capital outlay, offers a higher NPV and improved scalability compared to other charging solutions. For charging system designers and operators, it was found that rapid DC chargers can be classified by specific locations, each possessing a distinct Gaussian arrival pattern and Gamma distribution for charging energy delivered

Constrained Thompson Sampling for Real-Time Electricity Pricing with Grid Reliability Constraints

We consider the problem of an aggregator attempting to learn customers' load flexibility models while implementing a load shaping program by means of broadcasting daily dispatch signals. We adopt a multi-armed bandit formulation to account for the stochastic and unknown nature of customers' responses to dispatch signals. We propose a constrained Thompson sampling heuristic, Con-TS-RTP, that accounts for various possible aggregator objectives (e.g., to reduce demand at peak hours, integrate more intermittent renewable generation, track a desired daily load profile, etc) and takes into account the operational constraints of a distribution system to avoid potential grid failures as a result of uncertainty in the customers' response. We provide a discussion on the regret bounds for our algorithm as well as a discussion on the operational reliability of the distribution system's constraints being upheld throughout the learning process.Comment: 15 pages, IEEE Transactions on Smart Gri

Residential Sector Energy Consumption at the Spotlight: From Data to Knowledge

Energy consumption is at the core of economic development, but its severe impacts on resources depletion and climate change have justified a call for its general reduction across all economic activities. Lowering households’ energy demand is a key factor to achieve carbon dioxide emission reductions as it has an important energy-saving potential. Households in the European Union (EU28) countries have a significant weight (25%) in the total final energy consumption. However, a wide range of variation is observed within the residential sector from 7.6 to 37.4 GJ per capita/annum, with the lowest consumption indicator observed in Southern EU countries. Energy consumption in the residential sector is a complex issue, explained by a combination of different factors. To pinpoint how to reduce energy consumption effectively while deliver energy services, we need to look not just at technology, but also to the factors that drive how and in what extent people consume energy, including the way they interact with technology (i.e., energy efficiency). The main objective of this research is to understand the differences in energy consumption arising from different socio-demographic, technologic, behavioral and economic characteristics of residential households. This research brings to the spotlight the needs and benefits of looking deeper into residential sector energy consumption in a southern European country. Portugal and the municipality of Évora, in particular, were selected as case studies. Residential sector consumption is a moving target, which increase the complexity of adequate policies and instruments that have to address the bottleneck between increase demand for e.g. climatization due to current lack of thermal comfort and to comply with objectives of increased energy efficiency which ultimately intend to reduce energy consumption. This calls for different levels of knowledge to feed multiscale policies. This dissertation expands the understanding of energy consumption patterns at households, consumers’ role in energy consumption profiles, indoor thermal comfort, and the levels of satisfaction from energy services demand. In a country potentially highly impacted by climate change, with low levels of income and significant lower energy consumption per capita compared to the EU28 average, looking into these issues gains even more importance. The work combines detailed analysis at different spatial (national, city and consumers level) and time scales (hour to annual) taking advantage of diverse methods and datasets including smart meters’ data, door to door surveys and energy simulation and optimization modelling. The results identify (i) ten distinct residential sector consumer groups (e.g., under fuel poverty); (ii) daily and annual consumption patterns (W, U and flat); (iii) major energy consumption determinants such as the physical characteristics of dwellings, particularly the year of construction and floor area; climatization equipment ownership and use, and occupants’ profiles (mainly number and monthly income). It is (iv) recognized that inhabitants try to actively control space heating, but without achieving indoor thermal comfort levels. The results also show (v) that technology can overweight the impact of practices and lifestyle changes for some end-uses as space heating and lighting. Nevertheless, important focus should be given to the evolution in the future of uncertain parameters related with consumer behavior, especially those on climatization, related to thermal comfort and equipment’s use. Furthermore, the research work presents a (vi) bottom-up methodology to project detailed energy end-uses demand, and (vii) an integrated framework for city energy planning. This work sets the ground for the definition of tailor-made policy recommendations for targeted consumer groups (e.g., vulnerable consumers) and climatization behavior/practices to reduce peak demand, social support policies, energy efficiency instruments and measures, renewable energy sources integration, and energy systems planning

Alternative Energy Sources

The search for alternative sources of energy is an attempt to solve two of the main problems facing the modern world. Today's resources are mainly based on fossil flammable substances such as coal, oil, and natural gas. The first problem is related to the expected and observed depletion of deposits, not only those available but also less accessible. Another is related to global warming from emissions of greenhouse gases (mainly carbon dioxide) as well as emissions of other pollutants in the atmosphere. Mitigating the harmful effects of fossil fuel use is an obvious challenge for mankind. This Special Issue includes articles on the search for new raw materials and new technologies for obtaining energy, such as those existing in nature, methane hydrates, biomass, etc., new more efficient technologies for generating electricity, as well as analyses of the possibilities and conditions of use of these resources for practical applications