Approaching the Kyoto targets: a case study for Basilicata region (Italy)

Approaching the national Kyoto Protocol (KP) targets involves a re-definition of the actual configuration of local energy systems. This study deals with a local scale application of the IEA-MARKAL models generator, in which the anthropogenic system of Basilicata Region (Southern Italy) is investigated to support the definition of coherent long-term strategies and sound climate protection policies. A scenario by scenario analysis points out the behaviour of the optimal mix of fuels and technologies in the presence of carbon dioxide emissions constraints. Trade off curves and reduced costs analyses outline the most effective actions for contributing to the national KP targets, with particular emphasis on the interventions in Civil (Residential, Commercial & Services) and waste management sectors.     

Environmental assessment: (LCA) and spatial modelling (GIS) of energy crop implementation on local scale

Environmental analysis tools as LCA and GIS have been combined to provide an integrated methodology able to determine suitable areas for cultivating Brassica spp. (B. carinata and B. napus) and Populus spp and for proposing local and decentralised energy production and consumption scenario. The methodology is applied and verified in a Catalonia (southern Europe) case study area but it can be extrapolated to other Mediterranean regions with similar agroclimates.The results obtained show that a high impact reduction in potential global warming category can be achieved annually (annual reduction of 1,954,904 Mg of CO₂ eq.) in a local scale scenario.Environmental integration such as GIS and LCA provide a methodology capable of giving enough information and results to determine an energy crop implementation strategy for reducing energy consumption and CO₂ eq. emissions.     

Time series modelling of power output for large‐scale wind fleets

Simulations of power systems with high wind penetration need to represent the stochastic output of the wind farms. Many studies use historic wind data directly in the simulation. However, even if historic data are used to drive the realized wind output in scheduling simulations, a model of the wind's statistical properties may be needed to inform the commitment decisions for the dispatchable units. There are very few published studies that fit models to the power output of nation‐sized wind fleets rather than the output at a single location. We fitted a time series model to hourly, time‐averaged, aggregated wind power data from New Zealand, Denmark and Germany, based on univariate, second‐order autoregressive drivers. Our model is designed to reproduce the asymptotic distribution of power output, the diurnal variation and the volatility of power output over timescales up to several hours. For the cases examined here, it was also found to provide a generally good representation of the overall distribution of power output changes and the variation of volatility with power output level, as well as an acceptable representation of the distribution of calm periods. Copyright © 2011 John Wiley & Sons, Ltd.     

Large scale multi-zone creep finite element modelling of a main steam line branch intersection

A number of papers detail the non-linear creep finite element analysis of branch pieces. Predominately these models have incorporated only a single material zone representing the parent material. Multi-zone models incorporating weld material and heat affected zones have primarily been two-dimensional analyses, in part due to the large number of elements required to adequately represent all of the zones. This paper describes a non-linear creep analysis of a main steam line branch intersection using creep properties to represent the parent metal, weld metal, and heat affected zone (HAZ), the stress redistribution over 100,000 h is examined. The results show that the redistribution leads to a complex stress state, particularly at the heat affected zone. Although, there is damage on the external surface of the branch piece as expected, the results indicate that the damage would be more widespread through extensive sections of the heat affected zone. This would appear to indicate that the time between damage indications on the surface using techniques such as replication and full thickness damage may be more limited then previously expected.     

Safe heating-up of a full scale SOFC system using 3D multiphysics modelling optimisation

Heating-up strategies of full scale solid oxide fuel cell (SOFC) systems still affect the safe operation of the system and incorporation of the technology into the global energy sector. To ensure rapid start-up times whilst retaining the structural reliability of the SOFC system components, requires a safe heating-up operation. To master a controlled heating-up stage, detailed understanding of the component interaction and multiphysics within a fuel cell system is required. State of the art dynamic fuel cell system modelling comprises sub-models of the assembly, or is based on empirical nature. However, invaluable information of the multiphysics inside the system is lost. Therefore, it is of paramount importance to understand and improve the knowledge of the detailed processes, occurring within the interacting components. The effect of integrating different electrical heater cartridges at different locations has been thoroughly investigated to optimise the heating-up of the system. The study utilises a previously developed and experimentally validated full scale three dimensional planar type SOFC system model to mitigate experimental costs and shed light on the details, occurring within the system. A comparison to a simplified variant of the model has been added to shed light on its effect on the results.     

Design methodology and thermal modelling of industrial scale reactor for solid state hydrogen storage

In this study, a novel set of comprehensive arithmetic correlations has been proposed to design an industrial scale cylindrical reactor with embedded cooling tubes (ECT) for metal hydride (MH) based hydrogen storage and thermal management applications. Based on ASME standards, different nominal pipe sizes were imparted into a cylindrical reactor design with ECT to accommodate 50 kg of LaNi_4.7Al_0.3 alloy. A three dimensional numerical model has been developed using COMSOL Multiphysics 4.3a to predict the hydriding performance of designed reactors, which was further experimentally validated as well. At an absorption condition of 30 bar supply pressure and 298 K absorption temperature with 60 lpm volumetric HTF flow rate, 6 inch reactor with 99 ECT portrayed better heat transfer characteristics. From the parametric investigation, it is observed that the variation of supply pressure has predominant effect followed by the variation of the HTF flow rate on hydriding (absorption) kinetics of the device. However, the variation of absorption temperature has minuscule influence on the hydriding performance. At a supply condition of 30 bar and 298 K with water flow rate of 30 lpm, a hydrogen storage capacity (HSC) of 1.29 wt% was achieved within 2060 s.     

Control of ash related problems in a large scale tangentially fired boiler using CFD modelling

The objective of this study is to develop a three-dimensional combustor model for predicting the performance of full-scale tangential fired (TF) boiler and to determine the flow patterns of the gas and coal particles, with an emphasis on formation mechanism of gas flow deviations and uneven temperature on the super-heaters, re-heaters and divisional super-heater sections of the furnace. The importance of these simulations is to identify the locations of optimum additive injection ports to achieve maximum impact of additives in the combustion process to minimize the temperature deviation and reduce ash-related issues. This study is a classic example of numerical investigation into the problem of turbulent reacting flows in large scale furnaces employed in thermal power plants for the remediation of ash deposition problems. Present work also provides an investigation of the influence of number of tripped burners on the characteristics of the flow and thermal fields. Excellent agreement between the simulation results and key boiler design values and available site operation records following full-scale trials indicate that the calculations are reliable. The results obtained from the present work are directly relevant to coal-fired utilities for not only demonstrating the effectiveness of computational fluid dynamics (CFD) based tools in combating operational issues but also provides an alternative to conventional remediation strategies.     

The Kyoto mechanisms and the prospects for renewable energy technologies

The Kyoto Protocol to the Climate Change Convention sets out legally binding emission targets and timetables for developed countries. In order to ease compliance, it allows countries to achieve their emission targets through the ‘Kyoto Mechanisms’. These mechanisms comprise International Emissions Trading (ET), Joint Implementation (JI), and a Clean Development Mechanism (CDM). This paper analyses the capacity of the proposed mechanisms of the Kyoto Protocol to promote investment in renewable energy technologies (RETs). Analysis of abatement costing studies indicates that the increasing use of renewable energy tends to be a higher cost option compared with other greenhouse gas (GHG) abatement technologies. This finding, however, does not make RETs unattractive for GHG mitigation as such because, apart from their vast technical potential to reduce GHG emissions, RETs have great capacity to contribute to other aspects of sustainable development. The extent of investment into renewable energy induced by the Kyoto mechanisms will depend on whether the rules and guidelines that are to be developed in the coming years will explicitly support renewables. The Kyoto mechanisms could be instrumental in leading to significant investment into these resources if rules are defined appropriately.     

Prospects for tapping solar energy on a large scale

As a result of the energy conversion and storage research underway at Oklahoma State University since 1961, several components needed to engineer a continuous-duty energy system operating on replenishable solar energy have been developed to the prototype stage and are being tested. This paper presents and discusses these components and how they fit together in the solar energy systems envisioned for the long-term and immediate future.A simplified economic analysis of solar energy systems is presented, and the calculated generation costs are compared with those of conventional fuel burning systems for different fuel costs, load factors and interest rates. One result of this study is that wind energy systems, costing $125 to $150 per installed kW and pumping power directly into a.c. mains for 20 per cent of the time using the field-modulated generating systems developed at OSU, are competitive with conventional systems costing $250 to $350 per installed kW operating at a load factor of 80 per cent and fuel cost of $0·50 per MBtu. More such comparisons are included in the text of the paper.     

大中型沼气工程高压水洗提纯工艺的模拟

沼气高压水洗提纯工艺在我国尚处于起步阶段。针对国外水洗工艺规模适用于250 m3/h以上超大型工程,而我国大中型沼气工程在50 m3/h左右,缺乏合适水洗工艺的现状,文章基于CH4-CO2-H2S-H2O体系ELECNRTL热力学模型,构建了高压水洗全工艺流程,并对工艺关键参数,包括沼气处理量、补水量、沼气中甲烷浓度和H2S含量等对工艺的影响进行分析,在此基础上给出了水洗吸收塔和解吸塔参数。为发展我国沼气高压水洗工艺奠定了理论基础。     

Practical modelling of micro combined heat and power applications for local authority district heating schemes

The primary purposes of this paper are to describe a practical model which can be used to assist economic evaluation of district heating proposals, with particular reference to potential micro combined heat and power (CHP) applications, and to discuss the results of applying this model to a proposal for a particular scheme. The problems of realistic simulation of demand patterns, and the sensitivity of micro-CHP project values to scale, fuel prices, differential purchase/selling tariffs for electricity, duty cycle and plant utilization factors are discussed. Of several options, two were shown to be economically viable, relative to existing methods of supply (gas-fired boilers); however, the margin of benefit is small relative to wisely chosen modern boiler installations. A brief discussion of alternative methods of finance is provided; ceteris paribus, the proposed scheme would not be likely to attract venture capital from would-be lease-hire agencies. There is scope however for pilot schemes, whose results could be used to define more closely the limits of uncertainty of, for example, annual availability and duty cycle influences on the cost economics of operations.     

Spatially resolved current density measurements and real-time modelling as a tool for the determination of local operating conditions in polymer electrolyte fuel cells

In this contribution a simplified, isothermal, two-phase, one-dimensional model for the calculation of the cathodic gas flow along the flow field channels of a polymer electrolyte fuel cell (PEFC) is presented. The composition of the humidified oxidant gas, average gas velocity, pressure drop, and other quantities can be calculated for any gas distributor structures with one channel. Thereby, the model requires several input parameters which have to be determined solely by experiment and pre-defined operation conditions, e.g. the water content of the feed gas, local current densities, and gas flow rates. In contrast to other models, the cross-section reduction has been taken into account which results from the penetration of the gas diffusion layer into the flow field channels due to the mounting pressure. Beyond this, the model needs no fit-parameters for further adjustment.For close examination of the factors limiting the performance of a PEFC, the DLR has developed several techniques for measuring the current density distribution with spatial resolution. In order to investigate the origin of the corresponding effects, one of these techniques has been improved by implementing the model of the cathodic gas flow as an on-line feature.The combination of a spatially resolved measurement technique with a real-time simulation gives a better understanding of the local processes within the cell and represents a helpful tool for the development of fuel cell components as well as for the optimization of the operating conditions. Exemplarily, the presentation the results for a 25 cm² serpentine flow field at different operation modes are shown in this paper.     

Unsteady-state modelling for a passive liquid-feed DMFC

An unsteady-state model was developed for a liquid-feed Direct Methanol Fuel Cell (DMFC) delivery considering two-phase system. The model considered the mass and heat transport in the feed delivery system attached to the anode and cathode of the fuel cell. The results were then compared with the experimental data from in-house fabricated DMFC and steady-state model. It was observed that the unsteady-state model gave more similar results with experimental data then the steady-state model. The effects of feed methanol concentration in the reservoir and current density on mass transport to the catalyst layer were revealed.     

A guide to the Kyoto protocol: a treaty with potentially vital strategic implications for the renewables industry

Why should renewables advocates care about the arcane business of multilateral climate negotiations? The answer is simple. Because these long-running and oft bogged-down talks have as their ultimate objective a goal with seismic implications for energy markets: substantial reductions in greenhouse gas emissions. Coming anywhere close to that goal would entail the creation of multi-hundred billion dollar markets in renewables in the years ahead. And in Kyoto last December, governments took a meaningful first step in that direction.This paper is a brief summary, and analysis of that first step. It concludes with some observations about immediate implications for the renewables industries.     

Combined local microchannel-scale CFD modeling and global chip scale network modeling for electronics cooling design

Microchannel cold plates enjoy increasing interest in liquid cooling of high-performance computing systems. Fast and reliable design tools are required to comply with the fluid mechanics and thermal specifications of such complex devices. In this paper, a methodology accounting for the local as well as the device length scales of the involved physics is introduced and applied to determine the performance of a microchannel cooler. A unit cell of the heat transfer microchannel system is modeled and implemented in conjugate CFD simulations. The fluidic and thermal characteristics of three different cold plate mesh designs are evaluated. Periodic boundary conditions and an iteration procedure are used to reach developed flow and thermal conditions. Subsequently, two network-like models are introduced to predict the overall pressure drop and thermal resistance of the device based on the results of the unit cell evaluations. Finally, the performance figures from the model predictions are compared to experimental data. We illustrate the cooling potential for different channel mesh porosities and compare it to the required pumping power. The agreement between simulations and experiments is within 2%. It was found that for a typical flow rate of 250 ml/min, the thermal resistance of the finest microchannel network examined is reduced by 7% and the heat transfer coefficient is increased by 25% compared to the coarsest channel network. On the other hand, an increase in pressure drop by 100% in the case of densest channel network was found.     

Exploring the ancillary benefits of the Kyoto Protocol for air pollution in Europe

An integrated approach to climate change and regional air pollution can harvest considerable ancillary benefits in terms of environmental impacts and costs. This is because both problems are caused to a large extent by the same activity (fossil fuel combustion). Substantial ancillary benefits were found for regional air pollution (SO₂, NO_x, VOC and particulate matter) of implementing the Kyoto Protocol (intended to control greenhouse gas emissions) in Europe. For instance, while three different scenarios on Kyoto implementation were found to reduce European CO₂ emissions by 4–7%, they also reduced European emissions of SO₂ by 5–14% compared with a no Kyoto policies case. The magnitude of ancillary benefits depends on how flexible mechanisms and surplus emission allowances are used in meeting the Kyoto targets. The total cost savings for implementing current policies for regional air pollution of the Kyoto Protocol are of an order of 2.5–7 billion Euro. In all cases, this is in the order of half the costs of the climate policy (4–12 billion Euro). Using flexible mechanisms reduces emissions of air pollutants for Europe as a whole even further than domestic implementation (e.g. 10–14% versus 5% for SO₂ emissions), but the reductions are shifted from Western Europe to Central and Eastern Europe and Russia. The use of surplus emission allowances to achieve the Kyoto targets decreases the ancillary benefits, in particular for the latter group of countries (e.g. unprotected area against acidification increases from 1.3 to 1.7 million ha).     

A low-carbon scenario creation method for a local-scale economy and its application in Kyoto city

On May 2008, Kyoto city government set up a low-carbon target of a 50% GHG reduction by 2030 compared to the 1990 level. To contribute to these discussions, we developed a local (city-scale) low-carbon scenario creation method. An estimation model was developed to show a quantitative and consistent future snapshot. The model can explicitly treat the uncertainty of future socio-economic situations, which originate from the openness of local economy. The method was applied to Kyoto city, and countermeasures to achieve the low-carbon target were identified. Without countermeasures, emissions would increase 12% from 2000. Among the measures, the reduction potential of energy efficiency improvements to residential and commercial sectors was found to be relatively large (15% and 18% of total reductions, respectively). The reduction potential of the passenger transport sector, in which the city government's policy is especially important, was 17% of the total amount. A sensitivity analysis showed that a 10% increase in exports leads to an 8.5% increase in CO₂ emissions, and a 20% increase in the share of the commuters from outside the city leads to a 3.5% decrease of CO₂ emissions because of the smaller number of residents in the city.     

The implications of the Kyoto project mechanisms for the deployment of renewable electricity in Europe

EU energy/environmental policy has at least two major and interrelated goals: to increase the percentage of electricity from renewable energy sources (RES-E) and to control the emission of GHG cost efficiently. These two goals could be in conflict. This paper explores one aspect of this conflicting relationship, namely the effect that the use of the Kyoto Protocol project mechanisms (CDM/JI project) may have on the deployment of RES-E within EU borders.The main conclusion is that, under certain assumptions (i.e., no mandatory EU RES-E quota), CDM/JI projects might reduce the incentive to deploy RES-E within EU borders because they would allow European power companies to comply with GHG targets in a cheaper way than if they reduced emissions by investing in renewable electricity in Europe. This is problematic, since many benefits from renewable electricity are local and these would be gone. This situation would be different if a mandatory RES-E quota (combined with an EU-wide TGC scheme) was implemented. In this case, the RES-E target would be fulfilled and CDM/JI projects would only affect RES-E deployment exceeding the target.     

Impact of the Kyoto Protocol on the Iberian Electricity Market: A scenario analysis

This paper presents an assessment of the impact of the Kyoto Protocol on the Iberian Electricity Market during two periods: the first phase (2005–2007) and the second phase (2008–2012). A market-equilibrium model is used in order to analyze different conditions faced by generation companies. Scenarios involving CO₂-emission prices, hydro conditions, demand, fuel prices and renewable generation are considered. This valuation will show the significance of CO₂-emission prices as regards Spanish and Portuguese electricity prices, generation mix, utilities profits and the total CO₂ emissions. Furthermore, the results will illustrate how energy policies implemented by regulators are critical for Spain and Portugal in order to mitigate the negative impact of the Kyoto Protocol. In conclusion, the Iberian electricity system will not be able to reach the Kyoto targets, except in very favorable conditions (CO₂-emission prices over €15/ton and the implementation of very efficient energy policies).     

Simulation of the effect of scale deposition on a geothermal turbine

Dissolved chemicals contained in geothermal steam can lead to corrosion, erosion and deposition of scale on turbine blades, reducing their useful life. In addition, deposits on the blading system reduce the flow area of the turbine. The first-stage nozzle group is typically most affected by deposition of scale although scale may be present in other parts of the system. The most common deposits are of silica and calcium carbonate. This decreases the output capacity and efficiency of the turbine. This paper presents the results of simulations on the effect of scale deposition in the first-stage nozzle group on the steam pressure before and after the first stage, output capacity and efficiency of the turbine. By measuring the steam pressure before and after the first stage the change in the flow area can be estimated. A method of monitoring the percentage of nozzle plugging in real time is proposed. The method can be applied to any turbine that is susceptible to scale deposition.