Greet Van Eetvelde

Solar Commercial Virtual Power Plant

Installed photo voltaic energy grew exponentially during the last decade. One of the driving forces was the often generous governmental support. In Belgium (Flanders) for example, investors could acquire green power certificates worth €450/MWh during several years. However, due to the large boom of solar plants and hence rising subsidy cost, governments are dropping this support (eg. €450/MWh in 2009 to €90/MWh in 2012 for Flanders). In this paper the authors investigate if solar energy can become more profitable if forces are joined in a Commercial Virtual Power Plant to sell the solar power on the wholesale market. The numbers are based on the Flemish region, however, the same procedure can be applied to other markets as well. It turned out that for existing installations the potential benefits are marginal due to the small share of the energy revenue compared to the subsidy revenue in the total income of a solar plant. However, lower subsidies and coupling with other production resources and (flexible) consumers promise to be more profitable, although this needs more investigation.

Exploiting Properties of Legislative Texts to Improve Classification Accuracy

Organizing legislative texts into a hierarchy of legal topics enhances the access to legislation. Manually placing every part of new legislative texts in the correct place of the hierarchy, however, is expensive and slow, and therefore naturally calls for automation. In this paper, we assess the ability of machine learning methods to develop a model that automatically classifies legislative texts in a legal topic hierarchy. It is investigated whether such methods can generalize across different codes. In the classification process, the specific properties of legislative documents are exploited. Both the hierarchical structure of legal codes and references within the legal document collection are taken into account. We argue for a closer cooperation between legal and machine learning experts as the main direction of future work.

Solar commercial virtual power plant day ahead trading

During the past years, a large amount of photovoltaic (PV) capacity has been installed in Belgium. The main driver for this was the abundant government support (Green Power Certificates). However, during the last few years, the support for new installations has been withdrawn and new PV capacity ceased. In previous research, it has been proven that selling PV energy of existing plants directly on the wholesale market is not feasible due to the large share of green power certificates awarded to these plants. However, the price of green power certificates has dropped significantly and hence the balance between certificate and commodity revenue is restored. This paper investigates the risks and challenges of leaving the fixed rate system and trade directly on the more volatile day ahead markets while facing penalties resulting from wrong forecasts. It will be proven that nominating to much or not enough energy can be positive, but also yield large risks.

Renewable Energy Balancing with Thermal Grid Support

Waste heat valorisation in process industry is a common strategy today. The residual heat is converted to electricity by using steam turbines or organic Rankine cycles. As this energy conversion is likely constructed as an integral cooling capacity for the primary process, loss of electricity production will result in reduced process cooling and hence production capacity loss. This restriction prevents these generators to deliver supporting services to the electrical grid. In this paper, it is proven that coupling waste heat recovery with a district heating network provides flexibility to the electricity generation while ensuring cooling capacity to the process. This flexibility can be utilised by a Virtual Power Plant (VPP), e.g., to compensate for the variable output of renewable energy sources. Today, the power fluctuations are only compensated by traditional power plants (gas, coal) due to the scale and flexibility of these power plants. In this paper, a strategy is defined to balance variable (renewable) production with industrial waste heat. As such, some grid support tasks can be transferred from the central power plants to decentralised generation units. The backup of the variable sources is provided by utilising the local available capacity, while maintaining or improving energy efficiency of exothermal industrial processes. Operational boundaries are defined and new challenges identified. In this paper, firstly, the heat sources available for this concept are identified. Secondly, the properties of the different conversion technologies are described. Thirdly, the benefits of a virtual power plant utilising waste heat are determined. Finally, this VPP concept is verified by means of a case study in Belgium, Ostend Energy port. Available heat from biomass, chemical processing and waste incineration is used as primary energy source to balance local renewable production.

Techno-Economic Energy Models for Low Carbon Business Parks

To mitigate climate change, global greenhouse gas emissions need to be reduced substantially. Industry and energy sector together are responsible for a major share of those emissions. Hence the development of low carbon business parks by maximising energy efficiency and changing to collective, renewable energy systems at local level holds a high reduction potential. Yet, there is no uniform approach to determine the optimal combination and operation of energy technologies composing such energy systems. However, techno-economic energy models, custom tailored for business parks, can offer a solution, as they identify the configuration and operation that provide an optimal trade-off between economic and environmental performances. However, models specifically developed for industrial park energy systems are not detected in literature, so identifying an existing model that can be adapted is an essential step. In this paper, energy model classifications are scanned for adequate model characteristics and accordingly, a confined number of models are selected and described. Subsequently, main model features are compared, a practical typology is proposed and applicability towards modelling industrial park energy systems is evaluated. Energy system evolution models offer the most perspective to compose a holistic, but simplified model, whereas advanced energy system integration models can adequately be employed to assess energy integration for business clusters up to entire industrial sites. Energy system simulation models, however, provide deeper insight in the system’s operation.

Increasing Economic Benefits by Load-shifting of Electrical Heat Pumps

Electrical heating is still widely used in the process industry. While the use of immersion heaters for the production of hot water or steam is declining, the adoption rate of electrical heat pumps is increasing rapidly. Heat pumps show great flexibility and potential for energy savings, e.g. through low temperature waste heat recuperation. In combination with thermal storage they also allow for load shifting. Because their main power source is electricity, which up to now cannot be stored efficiently, heat pumps can transpose their thermal load shifting ability to the electrical grid. Today, more and more industrial electricity consumers are adopting energy supply contracts with variable pricing parameters strongly coupled to the energy trading market. Some large consumers even buy and sell on this market directly. In this paper it is proven that for customers with (hourly) variable electricity pricing, the use of electrical heat pumps can lead to additional cost savings without influencing the industrial process. The yield of the heat pumps can be increased during hours with low energy cost, with the thermal buffer absorbing the heat surplus. During hours with high energy cost the heat pump yield is lowered and stored heat is used by the industrial process. Considering that heat can be stored much more efficiently than electricity, the load shifting ability of heat pumps can also be utilised to provide stability on electrical smart grids and to increase electrical self-consumption on microgrids. This paper will also explore the potential of thermal storage through heat pumps for these electrical smart grid applications.

Energy management and dynamic optimisation of eco-industrial parks

As a result of the increasing number of distributed energy resources (DER) in the electrical grid and their commitment to future market participation, control strategies for optimal operation of DER within microgrids gain importance. Ensuring a smooth, reliable and economic operation of a micro-grid, requires an energy management system that dynamically fits the consumption to the production in combination with storage and vice versa. Quick response of an energy management strategy is crucial for a microgrid as compared to a conventional energy system. This paper discusses the possibilities offered by an energy management system in the operation of a microgrid. Various types of power management and control strategies, in particular for eco-industrial parks, are analysed and discussed. Subsequently, an environmentally friendly energy management optimisation technique is described in detail. The emphasis is placed on CO2 neutrality, energy management improvements and dynamical optimisation of electrical energy on eco-industrial parks.

A Methodology for Creating Sequential Multi-Period Base- Case Scenarios for Large Data Sets

Key performance indicators in engineering problems include but are not limited to financial, operational, management and environmental factors, which are significantly affected by aspects such as seasonality, fouling, economic climate, production rates, supply and demand. The search for an optimal solution to a problem must take into consideration this variability, otherwise running the risk of critical dimensioning or cost estimation errors. Testing solutions using full data sets covering large periods of time can be a computational challenge, and the analysis of results complicated. For the feasibility of such a study, it is therefore necessary to reduce the large data sets to a number of base case scenarios, which simultaneously reduce the number of data points to be handled while still representing the variability of the system. A novel method is therefore developed to address this problem. This method offers a way of designing an index of sequential periods common to each production level, which when averaged accurately represent periods of nominal values for each level. The method exploits a multi-objective evolutionary algorithm, minimising the standard deviation of the base cases compared to the real data as well as respecting crucial null value periods. Null value periods are typically found in turnarounds or supply and demand problems and are usually incorrectly represented in other methods. Lastly, the resulting base cases are sequential periods, which is important when dealing with scheduling, shutdown or storage problems. The method is tested using anonymised data and is compared to previously existing methods, with results showing improvement in the performance of the base cases with respect to the objective functions.

Thermal systems in process industry as a source for electrical flexibility

The need for balancing services in the European electricity grid is increasing. The reason is twofold: renewable energy sources (RES) are still in up rise, meanwhile the classical power plants — commonly used to provide balancing — are economically pushed out of the market. This results in less available balancing resources but increasing balancing needs as RES are less predictable and controllable. The decline of the balancing volume provided by classical power plants can be counteracted by the concept of Demand Side Response (DSR). Balancing services are shifted towards the electricity consumers instead of traditionally being an electricity producers responsibility. The concept of DSR is well documented as it was already introduced in 1973 at the time of the first energy (oil) crisis. Now, the DSR concept gains again momentum as electricity markets rapidly change to adopt RES. New insights and incentives are to be investigated as the electrical landscape has changed tremendously since the first introduction of DSR. This paper will focus on the concept of DSR in process industry.

Potential of domestically provided ancillary services to the electrical grid

In this paper we explore some methods to offer ancillary services by domestic demand response on a low voltage grid. These grids are becoming more and more inundated with decentralized renewable energy production, often leading to congestion issues. We show how domestically provided ancillary services can mitigate these problems. While demand response is already becoming established on large-scale installations, integration on a residential level poses some challenges toward cost and ease of integration. We present a solution that is both economic and non-intrusive and apply it on domestic electric water heaters. A project are where these solutions will be tested and verified is presented.