The ORé Tool: Decision Support for Defining a Building Retrofit Strategy at Territorial Scale

The heating energy represents 35% of total energy consumption in Switzerland, and private households 60% of this consumption. The retrofit of residential buildings is a fundamental component of local energy policies. However, questions remain unresolved for many Swiss cities such as: How to know the potential in terms of retrofit of the territory? What are the priority buildings and why? What strategy to implement to achieve the objectives and what impacts on energy, costs and climate? Based on regional data, calculation with the Swiss norm SIA 380/1 per building enriched with data from our own database, the CREM has developed a semi-automatized tool to define a strategy for renovation of housing buildings on any Swiss territory. The method implemented into the tool prioritizes the buildings for retrofit based on potential energy, monetary and greenhouse gas (GHG) savings. The detailed methodology is presented here.

Potential of refrigerant based district heating and cooling networks

Samuel Henchoz

Urban areas represent an ever increasing challenge in terms of energy use and environmental impact associated with it. Projections from the United Nation expect this number to reach 66% by 2050. In Europe 40% of the final energy consumption and 36% of the emissions of greenhouse gases are caused by buildings. The building sector is also one of the area where there is a great potential of reduction of the greenhouse gases emissions and of the dependence on fossil fuels. Among the measures that can help realise this potential, efficient energy conversion technologies supplying thermal energy services could play an important role. The present thesis aims at demonstrating the potential of a new type of district network, capable of delivering indistinctly cooling and heating services using a two-pipe network and in which the transfer of energy across the network is done by exploiting the evaporation/condensation of a refrigerant. The main research question is: "Is it possible to build and operate safe, reliable, energy efficient and economically profitable district heating and cooling networks that use a refrigerant as a transfer fluid?" The demonstration followsthree axes, the first being a thermoeconomic analysis. Thisanalysis focuses on a test case area in Genevaâs city centre where 5 variants of refrigerant based district heating and cooling networks, one cold water network and the mix of conversion technologies currently in use are compared on the basis of their energy and exergy performances and on the economic profitability. Considerations on economic uncertainty, safety and technical issues are also included in the analysis. The key findings are: â¢ All the variants of network can potentially reduce the final energy consumption of over 80% as compared to the current situation. â¢ All the variants of network have rather similar exergy efficiencies comprised between 39.5% and 45%. â¢ The most profitable variant uses CO2 as a transfer fluid and an open cycle CO2 heat pump at the central plant. It costs initially between 27 and 35 mio â¬ , reaches break-even in 4 to 6 years and the net present value after 40 years is comprised between 40 and 80 mio â¬. â¢ A cold water network is the second best option, although more expensive initially and thus less profitable, it has several advantages in terms of safety and availability of components. â¢ The CO2 variants exhibit a much better compactness than the cold water network. The second axis is the design, construction and testing of a lab scale refrigerant network. First a description of the design process and of the test facility is provided. It is followed by a presentation of the results of the test campaign. The tests aimed at demonstrating the practical feasibility of the concept, mostly by assessing the controllability of the network. Overall the good behaviour of the test facility and its ability to be smoothly and automatically controlled could be demonstrated, which further improved confidence in the practicality of the concept. The third axis is the development of dynamic models of simulation. These models are described in the present manuscript. They include, heat exchangers, pipes, pumps and valves. A short comparison between experimental and simulation results is also provided. The comparison between experiment and simulation showed that at their current stage of development the models cannot simulate accurately enough a refrigerant based network.

EPFL2016

Energy Efficiency and Integration in the Refining and Petrochemical Industries

Laurent Gabriel Félix Alexandre Stéphane Bungener

Industrial sites and their associated energy systems are estimated to be responsible for 31% of worldwide energy consumption. Improving their energy efficiencies has the potential to reduce production costs of industrial sites and contribute towards the 2050 CO2 emission targets. Energy efficiency and integration studies in industrial sites aim to reduce the import of energy from external sources and maximise the use of internal energy sources, thereby reducing overall losses. As refineries and petrochemical sites are major energy consumers and are often located close to each other, they offer substantial potential for synergies and Energy Integration solutions. This thesis explores the energy requirements of these two industries and the elaboration of methodologies to identify energy efficiency solutions tailored to them. Data collection, reconciliation and preparation make up the first three chapters of this work. Typical refining and petrochemical clusters are described in detail revealing significant data issues. Data reconciliation methods are adapted to the specificities of these industries to close mass and energy balances and calculate unknowns including losses. To facilitate complex engineering studies, a methodology to identify scenarios from large data sets is proposed. Two complementary methodologies for the generation and evaluation of Energy Integration solutions are developed in the final two chapters. Firstly Total Site Analysis is adapted to the target industries, allowing for minimal data collection through a dual representation of utility and process requirements, process stream modelling and results generation. A mathematical formulation for optimised operations of steam networks is augmented to include load shedding when operating reserves are low. This is included into a simulation of boiler failures to establish the resiliency of steam network configurations. The data preparation methodologies, Total Site Analysis and steam network optimisation and simulation are applied to a typical refining and petrochemical cluster case study to establish energy efficiency solutions resulting in significant reduction in energy consumption.

EPFL2016

Optimal use of biomass in large-scale energy systems: insights for energy policy

Victor Codina Gironès, François Maréchal, Stefano Moret, Marco Nasato, Emanuela Peduzzi

Biomass chemical conversion processes allow the production of solid, liquid and gaseous biofuels, which can substitute almost any kind of fossil fuel and the associated greenhouse gas emissions. Despite this potential, high investment costs and conversion losses reaching up to 30-40 % of the input biomass energy content are major barriers to a higher penetration rate of the chemical conversion processes. Thus, biomass is nowadays predominantly used in direct combustion processes. However, conversion losses of chemical processes may be compensated by the fact that biofuels can be used in more efficient technologies for supplying energy services compared to standard raw biomass fuelled technologies. As an example, Synthetic Natural Gas (SNG) can be used in a cogeneration-heat pump system to produce heat, reaching an overall efficiency much higher compared to a wood boiler. In this work biomass conversion options are compared taking into account the complete energy conversion pathway, from the resource to the supply of energy services. The comparison is performed by evaluating the CO2 abatement potential of integrating these different pathways into a national energy system with a Mixed-Integer Linear Programming (MILP) modelling approach. The comparison is done with 56 scenarios, which are classified in two different groups. Scenarios belonging to the first group consider the choice of the biomass chemical conversion process as the only possible change in the system. In the second group, other changes are allowed in the energy system, such as an important deployment of efficient technologies. Results show that biofuels can allow for an overall better performance in terms of avoided CO2 emissions compared to direct combustion. This potential, however, depends on a wider deployment of efficient end-use technologies.

University of Ljubljana2016

Optimal use of biomass in large-scale energy systems: insights for energy policy

Victor Codina Gironès, François Maréchal, Stefano Moret, Marco Nasato, Emanuela Peduzzi

University of Ljubljana2016

Potential of refrigerant based district heating and cooling networks

Samuel Henchoz

EPFL2016

Energy Efficiency and Integration in the Refining and Petrochemical Industries

Laurent Gabriel Félix Alexandre Stéphane Bungener

EPFL2016