Model Predictive Control Design for Unlocking the Energy Flexibility of Heat Pump and Thermal Energy Storage Systems

Heat pump and thermal energy storage (HPTES) systems, which are widely utilized in modern buildings for providing domestic hot water, contribute to a large share of household electricity consumption. With the increasing integration of renewable energy sources (RES) into modern power grids, demand-side management (DSM) becomes crucial for balancing power generation and consumption by adjusting end users' power consumption. This paper explores an energy flexible Model Predictive Control (MPC) design for a class of HPTES systems to facilitate demand-side management. The proposed DSM strategy comprises two key components: i) flexibility assessment, and ii) flexibility exploitation. Firstly, for flexibility assessment, a tailored MPC formulation, supplemented by a set of auxiliary linear constraints, is developed to quantitatively assess the flexibility potential inherent in HPTES systems. Subsequently, in flexibility exploitation, the energy flexibility is effectively harnessed in response to feasible demand response (DR) requests, which can be formulated as a standard mixed-integer MPC problem. Numerical experiments, based on a real-world HPTES installation, are conducted to demonstrate the efficacy of the proposed design.Comment: submitted to The 8th IEEE Conference on Control Technology and Applications (CCTA) 2024, 7 page

Towards energy efficient and healthy buildings: trade-off between Legionella pneumophila infection risk and energy efficiency of domestic hot water systems

The production of Domestic Hot Water (DHW) dominates the total energy demand. One of the main reasons for the high energy demand is that DHW is stored and distributed at temperatures above 55°C to mitigate the risk of infecting the DHW system with Legionella pneumophila. At these temperatures, Legionella pneumophila bacteria are effectively killed. For most of the applications of DHW, temperatures of only 30-40°C are required. This disparity (between 55 and 30-40°C) doubles the temperature difference between DHW system and environment and has a detrimental effect on the efficiency of DHW production units. A simulation model is developed that allows to investigate the infection risk for Legionella pneumophila in the design phase of a DHW system and to test the effectiveness of disinfection techniques on an infected system. By developing a simulation model that allows assessing the Legionella pneumophila infection risk in dynamic conditions, HVAC designers will be able firstly to thoroughly assess the infection risk associated with their design and secondly to optimize the temperature regimes, choose better hydronic controls and reduce the energy demand for DHW production. In addition to the modelling work, a test rig is built which will serve to run experiments that will allow testing, validating and improving the simulation model. In future research this thermodynamically validated model, will be used to assess the Legionella pneumophila infection risk of 5 to 10 often used DHW configurations from REHVA design guidelines for DHW systems and new design guidelines for these configurations will be proposed based on an optimization study that looks at the trade-off between Legionella pneumophila infection risk and energy efficiency

THE IMPACTS OF REMOVING FOSSIL FUEL SUBSIDIES AND INCREASING CARBON TAX IN IRELAND. RESEARCH SERIES NUMBER 98 December 2019

A subsidy is classified as potentially environmentally damaging if it is likely to incentivise behaviour that could be damaging to the environment irrespective of its importance for other policy purposes. Examples of such subsidies include providing fossil fuels (including diesel, kerosene, fuel oil, and peat) at lower prices to certain industries and providing fuel allowances to households to alleviate fuel poverty. While some publicly-funded supports can have important social and economic purposes, they can have a negative impact on the environment. While the main approach in Ireland to address this has been to use different excise duties, Ireland also introduced a carbon tax in 2010. The carbon tax is one of the primary fiscal policy tools used in several countries to reduce human-induced greenhouse gas (GHG) emissions. For the first time after the equalisation of its level on all fossil fuels in 2014, the Irish government increased the carbon tax from C20 per tonne of CO2 to C26 in 2020. It is expected that the total carbon tax revenues will increase by C100 million in 2020, compared to 2019. Notwithstanding this, the total budgetary cost of these fossil fuel subsidies, excluding the agriculturerelated ones, was around C2.44 billion in 2014, whereas the government’s total carbon tax collection was C390.9 million. In other words, the monetary value of environmentally damaging subsidies was over six times higher than carbon tax revenues. In 2017, the same ratio was slightly higher, since the total value of subsidies increased by 11.85%, whereas the growth rate of total carbon tax revenues was only 7.7%. This report analyses the economic and environmental impacts of the removal of eight different fossil fuel subsidies in Ireland by using the Ireland Economy-Energy-Environment (I3E) model. In addition, a separate set of scenarios in which the removal of each subsidy is accompanied by a gradual increase in the level of the carbon tax are run to quantify the combined effects of these policy instruments

Agent-based control for decentralised demand side management in the smart grid

Central to the vision of the smart grid is the deployment of smart meters that will allow autonomous software agents, representing the consumers, to optimise their use of devices and heating in the smart home while interacting with the grid. However, without some form of coordination, the population of agents may end up with overly-homogeneous optimised consumption patterns that may generate significant peaks in demand in the grid. These peaks, in turn, reduce the efficiency of the overall system, increase carbon emissions, and may even, in the worst case, cause blackouts. Hence, in this paper, we introduce a novel model of a Decentralised Demand Side Management (DDSM) mechanism that allows agents, by adapting the deferment of their loads based on grid prices, to coordinate in a decentralised manner. Specifically, using average UK consumption profiles for 26M homes, we demonstrate that, through an emergent coordination of the agents, the peak demand of domestic consumers in the grid can be reduced by up to 17% and carbon emissions by up to 6%. We also show that our DDSM mechanism is robust to the increasing electrification of heating in UK homes (i.e. it exhibits a similar efficiency)

Grey-box Modelling of a Household Refrigeration Unit Using Time Series Data in Application to Demand Side Management

This paper describes the application of stochastic grey-box modeling to identify electrical power consumption-to-temperature models of a domestic freezer using experimental measurements. The models are formulated using stochastic differential equations (SDEs), estimated by maximum likelihood estimation (MLE), validated through the model residuals analysis and cross-validated to detect model over-fitting. A nonlinear model based on the reversed Carnot cycle is also presented and included in the modeling performance analysis. As an application of the models, we apply model predictive control (MPC) to shift the electricity consumption of a freezer in demand response experiments, thereby addressing the model selection problem also from the application point of view and showing in an experimental context the ability of MPC to exploit the freezer as a demand side resource (DSR).Comment: Submitted to Sustainable Energy Grids and Networks (SEGAN). Accepted for publicatio

Quantifying the effects of higher world oil prices on recource allocation and living standards in an energy poor open economy

The OPEC Cartel's spectacular success in raising real world oil prices over the past decade has brought about substantial net resource transfers from energy poor to energy rich countries within the world economy. In accomodating these resource transfers both energy exporting and importing economies have been confronted with adjustment pressures. Of course the intensity and nature of these adjustment pressures has differed substantially between countries according to amongst other things a country's resource endowment, its net trade position with respect to oil and other energy based products and the degree of openness of its economy to world trade. Our concern in this paper is with quantifying the short and medium term adjustment pressures imposed on the South Korean economy assuming continued increases in real world oil prices. The results are derived from a multisectoral general equilibrium model. A feature of the model is its design flexibility and simple solution algorithm. We exploit this in the present study by comparing results for a range of experiments to accommodate differing assumptions about the Korean macroeconomic environment, labour market behaviour and Korean export demand. While the numerical results refer specifically to Korea, it is to be hoped that by rationalising them in terms of the underlying structural features inherent in the Korean economy the paper provides some guidance on the sorts of adjustment pressures likely to confront energy poor open economies assuming a continued movement in the world terms of trade towards oil.

Analysing Alternative Policy Response to High Oil Prices, Using an Energy Integrated CGE Microsimulation Approach for South Africa

An energy-focused integrated CGE microsimulation approach is used to assess the implications of differential government policy responses in South Africa, to increases in international oil prices. The first scenario assumes that increases in world oil and petroleum products are passed through to end users with no changes in government tax/subsidy instruments. The second scenario assumes that the world price increases are nullified by a full price subsidy by government in one scenario, while, in the third scenario, revenues generated from a 50 percent tax on the windfall profit of the synthetic petroleum industry, help to minimize the loss in government revenue. Overall output falls by between 2.2 and 2.5 percent, while the government deficit varies from a worsening of 12 to 22 percent under the three scenarios. Synthetic petroleum, coal, and electricity benefit under the floating price scenario, while none expands its output when a 50 percent tax is levied on the profit of the synthetic petroleum industry. Unemployment increases among medium and low-skilled workers, while skilled workers witness a substantial fall in their remuneration, particularly in rural areas. In both rural and urban areas, women are adversely affected relative to men. The poverty headcount ratio and inequality increase slightly more in the price-setting scenarios relative to the floating-price scenario. Thus, allowing the prices to be passed through to end users probably has a less adverse impact at a macroeconomic level, although there may be adverse distributional consequences.

SECTORAL EFFECTS OF A WORLD OIL PRICE SHOCK: ECONOMYWIDE LINKAGES TO THE AGRICULTURAL SECTOR

The effects of a world oil price shock on U.S. agriculture are analyzed in an economywide environment. We use an input-output model to analyze the direct and indirect cost linkages between energy and other sectors of the economy. Then, to allow sectoral output adjustment and the effects on the U.S. current account, we use the U.S. Department of Agricultural/Economic Research Service Computable General Equilibrium (CGE) model to analyze the sectoral effects under three different macro adjustment scenarios. The effects on agriculture are not limited to the direct and indirect energy costs and government support programs for agricultural also matter.Agricultural Finance, Resource /Energy Economics and Policy,