Athanasios Kolios

A framework for targeting household energy savings through habitual behavioural change

This paper reviews existing up-to-date literature related to individual household energy consumption. The how and why individual behaviour affects energy use are discussed, together with the principles and perspectives which have so far been considered in order to explain the habitual consuming behaviour. The research gaps, which are revealed from previous studies in terms of the limitations or assumptions on the methodology to alter individuals’ energy usage, give insights for a conceptual framework to define a comprehensive approach. The proposed framework suggests that the individual energy perception gaps are affected by psychological, habitual, structural and cultural variables in a wider-contextual, meso-societal and micro-individual spectrum. All these factors need to be considered in order for a variety of combined intervention methods, which are discussed and recommended, to introduce a more effective shift in the conventional energy-consuming behaviour, advancing insights for successful energy policies.

Application and extension of the TOPSIS method for the assessment of floating offshore wind turbine support structures

The offshore wind industry is shifting its focus towards deeper water sites, more suited to floating rather than bottom fixed support structures. Floating support structures currently used for oil and gas platforms provide a starting point for the floating wind industry; however, the selection of an optimum structure is not trivial with several unique factors that contribute to its complexity. In this work programme, a methodology to rapidly assess several concepts for wind turbine floating support structures is proposed. Using the multi-criteria decision-making method, TOPSIS, configurations are rated for a range of attributes. In addition, two complementary methodologies have been developed that extend the TOPSIS capability by including an estimated impact of the uncertainties associated with each of the selected criteria, on the final choice of an optimum support structure. This methodology represents a robust yet flexible design tool to complement the early conceptual design process that is able to rapidly investigate a broad design space and narrow down the number of potential options suitable for floating wind turbines.

Application of multi-criteria decision-making to risk prioritisation in tidal energy developments

This paper presents an analytical multi-criterion analysis for the prioritisation of risks for the development of tidal energy projects. After a basic identification of risks throughout the project and relevant stakeholders in the UK, classified through a political, economic, social, technological, legal and environmental analysis, relevant questionnaires provided scores to each risk and corresponding weights for each of the different sectors. Employing an extended technique for order of preference by similarity to ideal solution as well as the weighted sum method based on the data obtained, the risks identified are ranked based on their criticality, drawing attention of the industry in mitigating the ones scoring higher. Both methods were modified to take averages at different stages of the analysis in order to observe the effects on the final risk ranking. A sensitivity analysis of the results was also carried out with regard to the weighting factors given to the perceived expertise of participants, with different results being obtained whether a linear, squared or square root regression is used. Results of the study show that academics and industry have conflicting opinions with regard to the perception of the most critical risks.

Energy recovery from human faeces via gasification: A thermodynamic equilibrium modelling approach.

Highlights • On dry basis, typical human faeces contain 83 wt.% organic fraction and 17 wt.% ash.• The LHV of dry human faeces ranged from 19 to 22 MJ/kg, values similar to wood biomass.• Syngas from dry human faeces had LHV of 15–17 MJ/kg at equivalence ratio of ∼0.31.• Energy is best recovered from moist human faeces at equivalence ratio above 0.6.• Recoverable exergy potential from moist human faeces can be up to 15 MJ/kg.

Multi-criteria decision analysis of offshore wind turbines support structures under stochastic inputs

Selection of the optimum support structural configuration for offshore wind turbines is a decision that should take into account a variety of both technical and non-technical criteria in order to aggregate cumulatively the performance of several concepts such as jackets, tripods, monopiles, spars, semi-subs, tri-floaters and others with varying suitability and relevance to offshore wind applications. In the preliminary phases of a project, consideration of qualitative attributes based on experts’ opinions is a common practice due to the limited availability of quantitative data for attribute scores and relevant weights, which are mainly based on past experience. This practice can introduce a bias in the considered scores reducing the confidence of the qualifying solution. This paper documents the extension of the widely used TOPSIS method (Technique for Order of Preference by Similarity to Ideal Solution) to explicitly consider stochastic inputs (statistical distributions) following a systematic gathering of data through surveys and questionnaires. The methodology proposed has been efficiently implemented in a numerical tool and the case study that is presented on the decision analysis of an offshore wind turbine supports structure under given deployment conditions, illustrates its applicability and allows for a sensitivity analysis of the effect of the resolution of simulation, selection of statistical distributions and weighting of experts’ opinions based on their perceived level of expertise.

An experimental investigation of the combustion performance of human faeces

Highlights • Dry human faeces have a Higher Heating Value (HHV) of 24 MJ/kg.• Faeces combustion was investigated using a bench-scale downdraft combustor test rig.• Combustion temperature of 431–558 °C was achieved at air flow rate of 10–18 L/min.• Fuel burn rate of 1.5–2.3 g/min was achieved at air flow rate of 10–18 L/min.• Combustion temperature of up to 600 ± 10 °C can handle 60 wt.% moisture in faeces.

Experimental determination of the overturning moment and net lateral force generated by a novel vertical axis wind turbine: Experiment design under load uncertainty

Recent developments in harnessing wind energy propose new, radically different designs to alleviate some of the difficulties associated with conventional wind turbines. New designs however require testing for a variety of reasons ranging from gaining confidence in the analytical models used in the design and development through to satisfaction of certification requirements. Medium-scale prototype testing of large-scale concepts, where parameters such as the response of the structure and the loading conditions are often highly uncertain demand special consideration. This article presents the design of a special test rig and calculation methodology for the experimental determination of the overturning moment and net force generated by the NOVA Vertical Axis Wind Turbine using a field experimental setup. The design of the experimental model involves dealing with modelling uncertainties as loads in operation and therefore the response of the structure are largely unknown before testing has been carried out. The variability in the wind speed and direction also need to be accommodated for.

Influence of statistical uncertainty of component reliability estimations on offshore wind farm availability

Offshore wind turbine reliability, one of the industrys biggest sources of uncertainty, is the focus of the present paper. Specifically the impact of uncertain component failure distributions at constant failure rates has been investigated with respect to its implications for wind farm availability. A fully probabilistic offshore wind simulation model has been applied to quantify results; effects shown in this paper underline the significant impact that failure probability distributions have on asset performance evaluation. It was found that wind farm availability numbers may vary in the range up to 20 % just by changing the distributions of failure to a different pattern; in particular those scenarios in which extensive failure accumulation occurred led to significant losses in production. Results are interpreted and discussed mainly from the viewpoint of an offshore wind farm developer, owner and operator, with implications underlined for application in state-of-the-art offshore wind O&M (Operations and Maintenance) models and simulation tools.

A comparative multi-disciplinary policy review in wind energy developments in Europe

ABSTRACT Over recent decades, European Union countries have committed to increasing their electricity production from renewable energy sources (RESs). Wind energy plays a significant role in a sustainable future. This paper presents a political, economic, social, technological, legal and environmental analysis. Although these countries have made many improvements in their legal frameworks aiming to attract investors and boost the RE sector, there are still challenges. The UK focuses on offshore wind energy, adjusts the economic strategy and changes the legislation context. Germany has the healthiest economic conditions, as it keeps following its initiative to design a new programme for an energy transition from conventional to RESs with emphasis on the onshore. Greece has only a few installations and much room for development but needs to make further changes in the legislation and economy so as to attract more investors in the long term. The purpose of this research is to analyse, highlight and discuss vital aspects of these countries as well as the European environment, with reference to their current wind energy activities. Ultimately, it attempts to give a wider perspective and to serve as a guide for future studies on the wind energy sector.

Conceptual energy and water recovery system for self-sustained nano membrane toilet

Highlights • Energy and water recovery system from human excreta is modelled in Aspen Plus.• The Nano Membrane Toilet is proven to be a self-sustained system.• Up to 87% of total amount of water fed to the system can be recovered.• Net power output of the entire system is similar to the USB port peak power (2–6 W).• The specific net power output varies between 23.1 and 69.2 Wh/kgsettledsolids.