Is the relative thickness of ammonoid septa influenced by ocean acidification, phylogenetic relationships and palaeogeographic position?

The impact of increasing atmospheric CO2 and the resulting decreasing pH of seawater are in the focus of current environmental research. These factors cause problems for marine calcifiers such as reduced calcification rates and the dissolution of calcareous skeletons. While the impact on recent organisms is well established, little is known about long-term evolutionary consequences. Here, we assessed whether ammonoids reacted to environmental change by changing septal thickness. We measured the septal thickness of ammonoid phragmocones through ontogeny in order to test the hypothesis that atmospheric pCO2, seawater pH and other factors affected aragonite biomineralisation in ammonoids. Particularly, we studied septal thickness of ammonoids before and after the ocean acidification event in the latest Triassic until the Early Cretaceous. Early Jurassic ammonoid lineages had thinner septa relative to diameter than their Late Triassic relatives, which we tentatively interpret as consequence of a positive selection for reduced shell material as an evolutionary response to this ocean acidification event. This response was preserved within several lineages among the Early Jurassic descendants of these ammonoids. By contrast, we did not find a significant correlation between septal thickness and long-term atmospheric pCO2 or seawater pH, but we discovered a correlation with palaeolatitude

Multi-objective design and optimization of district energy systems including polygeneration energy conversion technologies

In the present context of finding ways to decrease CO2 emissions linked with human activity, district energy systems including polygeneration energy conversion technologies are likely to play a major role. District energy systems meet the heating, hot water, cooling and electricity requirements of a district. Because they meet several types of energy requirements, and for more than one single building, district energy systems represent good opportunities to implement polygeneration energy conversion technologies. Polygeneration energy conversion technologies indeed provide different energy services simultaneously, helping to decrease the CO2 intensity compared to energy conversion technologies that meet only one energy service. Moreover, when providing energy to a whole district, polygeneration energy conversion technologies can take advantage of the various load profiles of the buildings by compensating the fluctuations and having therefore a smoother operation. A district energy system comprises essentially two parts: the plant with the polygeneration energy conversion technologies, and the distribution networks (heating and cooling). When designing the energy system for a district, one has therefore to define which type of polygeneration energy conversion technologies are best suited for the district, as well as which building are worse connecting to the system and which buildings shouldn't be connected (for instance if they are located too far away from the other buildings or if they have too small requirements to justify a connection from the plant). Moreover the operation strategy needs to be defined. In the present thesis, a method is developed that helps designing and optimizing district energy systems, from the structuring of the information available for the district (energy consumption profiles, location of the buildings, available energy sources, possible layouts for the pipes,...), over the thermo-economic modelling of the energy conversion technologies, the design of the network and the simulation of its operation strategy, and finally the evaluation of the results in terms of CO2 emissions and costs. The design and optimization of the district energy system is a multi-objective Mixed Integer Non Linear Programming problem. To solve this problem, a decomposition strategy including a master and a slave problem was developed. The master optimization problem takes care of the energy conversion technologies, whereas the slave optimization problem optimizes the network part. The two sub-problems are solved iteratively and result in the definition of a Pareto optimal curve that gives the trade-offs between the emissions and the costs for various configurations satisfying the requirements of the district. A configuration is characterized by given types and sizes of energy conversion technologies, their location in the district, the network layout, as well as the operation strategy of the technologies. Due to the time dependent energy consumption profiles and the geographical location of the buildings and plant, the method developed combines two well known types of problems, namely the multi-period optimization problems and the network problems. The method developed allows to take into account various constraints such as limited availability of energy sources, forbidden connections between buildings (for instance if a large river separates these two buildings), or else space limitations in underground technical channels. The capabilities of the method are demonstrated by means of a test case, as well as a real case in the Canton of Geneva. The results show the importance of considering all the energy services together (and not separately). Energy systems including a gas engine or a gas turbine combined cycle, together with heat pumps, indeed help decreasing both the emissions and the costs compared to the actual configurations. In the Geneva case study for instance, emissions can be decreased by up to 45%, with a simultaneous costs reduction of 24%. However, the method only deals with water networks, while in some cases space limitations and safety issues make the use of water impossible. A new type of district energy system based on CO2 as energy transfer medium (instead of water), is therefore developed in order to take such issues into account. This new system, that led to the submission of a patent, meets all the different types of energy requirements with only two pipes (instead of three or four like in conventional water based system), and uses the latent heat of CO2 as driving force, instead of the specific heat

Conventional and advanced district energy systems

District energy systems have the potential to decrease the CO2 emissions linked to energy services (heating, hot water, cooling and electricity), thanks to the implementation of large polygeneration energy conversion technologies, connected to a group of buildings over a network. To transfer the energy from the large polygeneration energy conversion technologies to the users, conventional district energy systems use water as energy transfer medium with often two independent supply and return piping systems for heat and cold. However, sharing energy or interacting with decentralized heat pump units often results in relatively large heat transfer exergy losses due to the large temperature differences that are economically required from the water network. Using refrigerants as a district heating or cooling fluid at an intermediate temperature could alleviate some of these drawbacks. Because of the environmental concerns about conventional refrigerants, CO2, which is a natural refrigerant, used under its critical point, could be an interesting candidate. Pipe sizing of a multiservices superstructure, based on a two pipe CO2 network at 18°C is compared with a standard 4 pipes water network for heating and cooling

Multi-Objective Design and Optimisation of Urban Energy Systems

Product Description Inspired by the leading authority in the field, the Centre for Process Systems Engineering at Imperial College London, this book includes theoretical developments, algorithms, methodologies and tools in process systems engineering and applications from the chemical, energy, molecular, biomedical and other areas. It spans a whole range of length scales seen in manufacturing industries, from molecular and nanoscale phenomena to enterprise–wide optimization and control. As such, this will appeal to a broad readership, since the topic applies not only to all technical processes but also due to the interdisciplinary expertise required to solve the challenge. The ultimate reference work for years to come. From the Back Cover This fifth volume in the series is the first comprehensive source on energy systems engineering for the process industries. As such, it combines key contributions from leading research groups to form a single source of vital information otherwise dispersed among specialized journals. Inspired by the leading authority in the field, the Centre for Process Systems Engineering at Imperial College London, this interdisciplinary work explores new technologies of sustainable energy sources and their optimization as energy sufficient systems. The innovative technologies thus covered are crucial for the continued growth of already established multi–billion–dollar commercial markets: oil and gas, petrochemicals, pharmaceuticals and fine chemicals, food and beverage and consumer goods. From the contents: ∗ Polygeneration systems engineering ∗ Integrated oil & gas optimization ∗ Technologies for hydrogen production and storage ∗ Wind farm modeling, control and optimization ∗ Thermo–economic design ∗ Energy efficiency and carbon footprint reduction ∗ Energy systems solutions in the pulp and paper industry ∗ CO2 capture from natural gas ∗ Hydrogen infrastructure design and optimization ∗ Chance–constrained optimization of investment planning problems in the electric power industry For chemical, process and automation engineers, as well as those working in measurement and control, and for lecturers in these fields, this is the ultimate reference work for years to come

Performance and Profitability Perspectives of a CO2 based District Energy Network in Geneva’s City Center

A new type of district energy network capable of providing simultaneously heating and cooling is being investigated. It is based on the use of CO2 as a heat transfer fluid by taking advantage of the latent heat of vaporization, to store and transfer heat across the network. The goal of the present study is to determine the performance of a CO2 network when applied to a real urban area. It focuses first on determining the requirements for the various thermal energy services for a part of Geneva’s city centre. The energy consumption is first computed for the energy conversion technologies now in place in this area - namely fuel boilers and vapour compression chillers. Then the new energy consumption is computed if a CO2 network were used instead of the existing technology. Finally a profitability analysis of the CO2 network variant is done accounting for investment, energy purchasing, equipments replacement, operation, and maintenance costs. For an interest rate of 6% and a price of the delivered heating/cooling energy at 0.13 CHF per kWh, a net present value of 82.8 million CHF after 40 years is achieved, while the break-even is reached after 5 years of operation

Design and optimization of district energy systems

District energy systems have the potential to decrease the CO2 emissions linked to energy services (heating, hot water, cooling and electricity), thanks to the implementation of large polygeneration energy conversion technologies, connected to a group of buildings over a network. The synthesis of district energy systems requires a large number of integer and continuous variables involved in non linear models, resulting in a mixed integer non linear programming problem (MINLP). A new method is being developed to design district energy systems, by decomposing the multi-objective optimization problem into two sub-problems: a master optimization problem and a slave optimization problem. In this paper, the method developed as well as the first results of the complete resolution procedure are presented

Network synthesis for district heating with multiple heat plants

In this paper the first results of a new method for the configuration of district energy systems are presented. District energy systems are believed to help decreasing the CO2-emissions due to energy services (heating, cooling, electricity and hot water), by implementing polygeneration energy conversion technologies. However, because polygeneration technologies are complex, it is meaningful to use them not just for one single building, but for several buildings connected together with a network. The configuration of the network is an important but not trivial task, mainly because the problem involves a large number integer variables and results in an MILP that needs to be optimised

SoLid : Search for Oscillations with Lithium-6 Detector at the SCK-CEN BR2 reactor

Sterile neutrinos have been considered as a possible explanation for the recent reactor and Gallium anomalies arising from reanalysis of reactor flux and calibration data of previous neutrino experiments. A way to test this hypothesis is to look for distortions of the anti-neutrino energy caused by oscillation from active to sterile neutrino at close stand-off (similar to 6-8m) of a compact reactor core. Due to the low rate of anti-neutrino interactions the main challenge in such measurement is to control the high level of gamma rays and neutron background. The SoLid experiment is a proposal to search for active-to-sterile anti-neutrino oscillation at very short baseline of the SCK center dot CEN BR2 research reactor. This experiment uses a novel approach to detect anti-neutrino with a highly segmented detector based on Lithium-6. With the combination of high granularity, high neutron-gamma discrimination using 6LiF:ZnS(Ag) and precise localization of the Inverse Beta Decay products, a better experimental sensitivity can be achieved compared to other state-of-the-art technology. This compact system requires minimum passive shielding allowing for very close stand off to the reactor. The experimental set up of the SoLid experiment and the BR2 reactor will be presented. The new principle of neutrino detection and the detector design with expected performance will be described. The expected sensitivity to new oscillations of the SoLid detector as well as the first measurements made with the 8 kg prototype detector deployed at the BR2 reactor in 2013-2014 will be reported