There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

世界経済・社会統計 = World development indicators

2 1 The innovative transport systems and the CityMobil project 10 1.1 The research questions 10 2 The state of art in the field of automatic transport systems 12 2.1 Case studies and demand studies for innovative transport systems 12 3 The design and implementation of surveys 14 3.1 Definition of experimental design 14 3.2 Questionnaire design and delivery 16 3.3 First analyses on the collected sample 18 4 Calibration of Logit Multionomial demand models 21 4.1 Methodology 21 4.2 Calibration of the “full” model. 22 4.3 Calibration of the “final” model 24 4.4 The demand analysis through the final Multinomial Logit model 25 5 The analysis of interaction between the demand and socioeconomic attributes 31 5.1 Methodology 31 5.2 Application of Mixed Logit models to the demand 31 5.3 Analysis of the interactions between demand and socioeconomic attributes through Mixed Logit models 32 5.4 Mixed Logit model and interaction between age and the demand for the CTS 38 5.5 Demand analysis with Mixed Logit model 39 6 Final analyses and conclusions 45 6.1 Comparison between the results of the analyses 45 6.2 Conclusions 48 6.3 Answers to the research questions and future developments 52

The European commission

Climate change 2014 - Synthesis Report

The increasing diffusion of distributed generation within urban areas calls for deeper analyses aimed at evaluating the sustainability of energy generation and its environmental impact. In particular, cogeneration technologies enable enhanced energy efficiency and thus CO2 emission saving with respect to the conventional separate production of heat and electricity. However, the distributed cogeneration production could dramatically worsen the air quality on a local level, due to emissions of various hazardous pollutants such as NO2, CO, and so on. In addition, in urban areas the air quality regulation could be quite stringent, thus calling for a thorough environmental impact assessment at the planning stage. In this paper, the emission characteristics of distributed cogeneration are evaluated with respect to the conventional separate production of heat and electricity on the global and local levels through the emission balance approach. The analysis is carried out with reference to small-scale (below 1 MWe) distributed generation technologies available on the market, such as microturbines and internal combustion engines. In particular, after evaluating the emission break-even conditions for equivalence between distributed and centralized generation, it is shown how the specific results may depend upon the plant operation characteristics (at partial load) and upon the reference values for emission assessment. These aspects could be particularly relevant for energy policy formulations.

Emission Assessment of Distributed Generation in Urban Areas

The integration of Renewable Energy Sources (RES) and the electrification of the heating and transportation sectors are stressing the operation of current power systems and call for more flexibility. Domestic electric heat pumps (EHP), which are expected to be widely deployed in the future, can be considered as one potential source of such system flexibility. However, this can also lead to negative impacts for building occupant comfort and to increased peak demand, through reduction in load diversity. Such impacts may be mitigated through the deployment of Thermal Energy Storage (TES), although the benefit this brings is not well understood. Therefore, this paper presents a method to quantify the impact on occupant comfort level and load diversity, through various payback metrics. A validated model is then used to simulate the extraction of reserve capacity from a cluster of 500 domestic buildings with EHPs and different configurations of space heating buffer. Performance in terms of occupant comfort and payback is evaluated.

/pdf/exploring-flexibility-of-aggregated-residential-electric-525hp4y2u5.pdf

Exploring flexibility of aggregated residential electric heat pumps

This chapter presents an overview of the barriers to smart, demand-side interventions for neighborhoods and districts. Barriers are classified as political/regulatory, economic, social, and technological. Subsequently, drawing on experience from the COOPERaTE project, the specific challenges for the implementation of the Energy Positive Neighborhood (EPN) concept are reviewed. These challenges are presented in classifications of: energy modeling and simulation, performance assessment, information technology, and business model development. Finally, recommendations to aid implementation of the EPN concept and, more generally, smart district and demand-side interventions are detailed.

Barriers, Challenges, and Recommendations Related to Development of Energy Positive Neighborhoods and Smart Energy Districts

Power systems with increasing flexibility requirements are increasingly relying on gas turbines to follow the net-load and the gas network to support unforecast changes in gas turbine generation. In addition, the role of the gas network in supplying fuel for the heating sector means that alternative heating scenarios can impact the gas network's ability to provide this flexibility. In this light, this paper presents a novel methodology for the assessment of the impact of heating on the integrated flexibility of the gas and electrical transmission networks. The model considers the transport requirements of gas for the heating sector as well as the regional distribution of gas within the gas network in the context of zonal linepack distribution. Electrical network modelling is conducted using a DC OPF while the gas network flexibility is assessed using a novel iterative steady-state gas flow methodology. Case studies are performed on the British networks and highlight how in energy systems with a large heat-based gas demand then extreme cold days can reduce the flexibility of the gas network while, on milder days, the use of gas turbines in supplying an electrified heating sector can lead an increase in linepack swing.

Assessment of the impact of heating on integrated gas and electrical network flexibility

This article presents the modeling foundations to study the capabilities of hydrogen electrolyzers (HEs) to provide frequency control ancillary services (FCAS), including virtual inertia and primary and secondary frequency response. To do so, we propose a general, unified HE dynamic model for the electrolyzer stack circuit, power-electronics interface (PEI), and relevant converter-level control loops. The equivalent circuit of the stack is derived from its current transfer function, with poles and zero obtained from its step response characteristics (e.g., rise/settling time). The stack model also considers relevant physical nonlinearities and downstream hydrogen buffer/process operational constraints. The PEI control loops account for stack model parameters, hydrogen production operational constraints, stack temperature dynamics, and active power reference generation strategy for contingency and regulation frequency support services. Further, we propose a virtual synchronous machine (VSM) control approach to study the VSM HE capabilities to also provide virtual inertia response. We apply the modeling to both alkaline and proton exchange membrane (PEM) technologies, including design of appropriate control schemes. Finally, we assess the FCAS performance of alkaline and PEM HEs via dynamic simulation of the Australian south-east interconnection in a 50%-renewable scenario, also discussing comparison and cooperation with battery energy storage systems.

Pierluigi Mancarella

Papers

Emission Assessment of Distributed Generation in Urban Areas

Exploring flexibility of aggregated residential electric heat pumps

Barriers, Challenges, and Recommendations Related to Development of Energy Positive Neighborhoods and Smart Energy Districts

Assessment of the impact of heating on integrated gas and electrical network flexibility

Virtual Inertia Response and Frequency Control Ancillary Services From Hydrogen Electrolyzers