Improving safety in Greek road tunnels

Tunnels are regarded as one of the most important infrastructures in Europe, as they may improve the connection of regions and aid economic development through facilitating the transportation of people and goods. In order to achieve a minimum acceptable level of safety, the EC issued Directive 2004/54/EC, which describes specific safety measures that have to be taken for all road tunnels in the trans-European road network. In parallel, there are several qualitative or quantitative methods for measuring road tunnel safety, while the method that seems to be the most accepted by administrative authorities for quantitative risk analysis is the OECD/PIARC QRA Model (QRAM), which has been developed by INERIS, WS-Atkins and the Institute for Risk Research. QRAM is based on engineering software that aids quantitatively assessment of the societal risk due to transporting goods and dangerous goods with Heavy Goods Vehicles (HGV) through road tunnels. The aim of this paper is to expose the effectiveness of the measures imposed by the EC in Greek road tunnels. A typical road tunnel, as designed and implemented after Directive 2004/54/EC, is compared to the same tunnel as if it was developed before the Directive was put into action. The comparison is made on the basis of the societal risk existing in the two cases. The conclusion of the paper, based on the outcome of the risk analysis with the QRAM method, is that the safety of Greek Tunnels is significantly improved due to the implementation of the measures imposed by the EC Directive 2004/54/EC

Investment planning in electricity production under CO2 price uncertainty

The scope of this work is to investigate the effect that various scenarios for emission allowance price evolution may have on the future electricity generation mix of Greece. The renewable energy generation targets are taken into consideration as a constraint of the system, and the learning rates of the various technologies are included in the calculations. The national electricity generation system is modelled for long-term analysis and an optimisation method is applied, to determine the optimal generating mix that minimises electricity generation cost, while satisfying the system constraints and incorporating the uncertainty of emission allowance prices. In addition, an investigation is made to identify if a point should be expected when renewable energy will be more cost-effective than conventional fuel electricity generation. The work is interesting for investment planning in the electricity market, as it may provide directions on which technologies are most probable to dominate the market in the future, and therefore are of interest to be included in the future power portfolios of related investors. (C) 2010 Elsevier B.V. All rights reserved

Comparative techno-economic analysis of ORC and gasification for bioenergy applications

The use of biomass for decentralized energy production has undergone a significant development the last years. The fact that this fuel is CO(2)-free provides many advantages in European and world aims for sustainable energy sources. Biomass trigeneration is a relatively new concept, which has the potential to improve the bioenergy economics for areas with warm climate, for which traditional biomass cogeneration was unfeasible. This concept can be applied with various energy conversion technologies, two of which are investigated in this paper: ORC and gasification. Both technologies are applied for a specific case study. The technological and financial comparison of the two technologies shows that gasification offers improved yield for the investment, mainly due to the higher electrical efficiency factor. However, attention should be placed to the increased investment risk of gasification projects, which could be an aversive factor for some investors. (C) 2008 Elsevier Ltd. All rights reserved

An optimization model for multi-biomass tri-generation energy supply

In this paper, a decision support system (DSS) for multi-biomass energy conversion applications is presented. The system in question aims at supporting an investor by thoroughly assessing an investment in locally existing multi-biomass exploitation for tri-generation applications (electricity, heating and cooling), in a given area. The approach followed combines use of holistic modelling of the system, including the multi-biomass supply chain, the energy conversion facility and the district heating and cooling network, with optimization of the major investment-related variables to maximize the financial yield of the investment. The consideration of multi-biomass supply chain presents significant potential for cost reduction, by allowing spreading of capital costs and reducing warehousing requirements, especially when seasonal biomass types are concerned. The investment variables concern the location of the bioenergy exploitation facility and its sizing, as well as the types of biomass to be procured, the respective quantities and the maximum collection distance for each type. A hybrid optimization method is employed to overcome the inherent limitations of every single method. The system is demand-driven, meaning that its primary aim is to fully satisfy the energy demand of the customers. Therefore, the model is a practical tool in the hands of an investor to assess and optimize in financial terms an investment aiming at covering real energy demand. optimization is performed taking into account various technical, regulatory, social and logical constraints. The model characteristics and advantages are highlighted through a case study applied to a municipality of Thessaly, Greece. (C) 2008 Elsevier Ltd. All rights reserved

Optimisation of electricity energy markets and assessment of CO2 trading on their structure : a stochastic analysis of the greek power sector

Power production was traditionally dominated by monopolies. After a long period of research and organisational advances in international level, electricity markets have been deregulated allowing customers to choose their provider and new producers to compete the former Public Power Companies. Vast changes have been made in the European legal framework but still, the experience gathered is not sufficient to derive safe conclusions regarding the efficiency and reliability of deregulation. Furthermore, emissions' trading progressively becomes a reality in many respects, compliance with Kyoto protocol's targets is a necessity, and stability of the national grid's operation is a constraint of vital importance. Consequently, the production of electricity should not rely solely in conventional energy sources neither in renewable ones but on a mixed structure. Finding this optimal mix is the primary objective of the study. A computational tool has been created, that simulates and optimises the future electricity generation structure based on existing as well as on emerging technologies. The results focus on the Greek Power Sector and indicate a gradual decreasing of anticipated CO2 emissions while the socioeconomic constraints and reliability requirements of the system are met. Policy interventions are pointed out based on the numerical results of the model. (C) 2010 Elsevier Ltd. All rights reserved

Time-dependent opportunities in energy business : a comparative study of locally available renewable and conventional fuels

This work investigates and compares energy-related, private business strategies, potentially interesting for investors willing to exploit either local biomass sources or strategic conventional fuels. Two distinct fuels and related power-production technologies are compared as a case study, in terms of economic efficiency: the biomass of cotton stalks and the natural gas. The carbon capture and storage option are also investigated for power plants based on both fuel types. The model used in this study investigates important economic aspects using a "real options" method instead of traditional Discounted Cash Flow techniques, as it might handle in a more effective way the problems arising from the stochastic nature of significant cash flow contributors' evolution like electricity, fuel and CO(2) allowance prices. The capital costs have also a functional relationship with time, thus providing an additional reason for implementing, "real options" as well as the learning-curves technique. The methodology as well as the results presented in this work, may lead to interesting conclusions and affect potential private investment strategies and future decision making. This study indicates that both technologies lead to positive investment yields, with the natural gas being more profitable for the case study examined, while the carbon capture and storage does not seem to be cost efficient with the current CO(2) allowance prices. Furthermore, low interest rates might encourage potential investors to wait before actualising their business plans while higher interest rates favor immediate investment decisions. (C) 2009 Elsevier Ltd. All rights reserved

Optimisation and investment analysis of two biomass-to-heat supply chain structures

As oil prices have risen dramatically lately, many people explore alternative ways of heating their residences and businesses in order to reduce the respective cost. One of the options usually considered nowadays is biomass, especially in rural areas with significant local biomass availability. This work focuses on comparing two different biomass energy exploitation systems, aiming to provide heat to a specific number of customers at a specific cost. The first system explored is producing pellets from biomass and distributing them to the final customers for use in domestic pellet boilers. The second option is building a centralised co-generation (CHP) unit that will generate electricity and heat. Electricity will be fed to the grid, whereas heat will be distributed to the customers via a district heating network. The biomass source examined is agricultural residues and the model is applied to a case study region in Greece. The analysis is performed from the viewpoint of the potential investor. Several design characteristics of both systems are optimised. In both cases the whole biomass-to-energy supply chain is modelled, both upstream and downstream of the pelleting/CHP units. The results of the case study show that both options have positive financial yield, with the pelleting plant having higher yield. However, the sensitivity analysis reveals that the pelleting plant yield is much more sensitive than that of the CHP plant, therefore constituting a riskier investment. The model presented may be used as a decision support system for potential investors willing to engage in the biomass energy field

Quantitative operational risk analysis for dangerous goods transportation through cut and cover road tunnels

This paper deals with risk analysis in cut and cover road tunnels. The research question explored is whether dividing a long tunnel into shorter sections would affect the safety when dangerous goods are allowed through the tunnel. In order to conclude the OECD/PIARC QRA Model quantitative risk analysis tool was used. Initial findings reveal that there is no evidence of increase in safety from dividing a long urban cut and cover tunnel in smaller parts with open air areas in between. However, the overall safety depends to a great extend on the specific characteristics of each particular case, since there are many factors that influence the overall safety of road tunnels. Therefore it is concluded that risk analysis using systemic approach is crucial for any road tunnel