Developing novel 5th generation district energy networks

Energy, Published online March 19, 2020
Authors: Akos Revesz, Phil Jones, Chris Dunham, Gareth Davies, Catarina Marques, Rodrigo Matabuena, Jim Scott, Graeme Maidment

Key words: Thermal Power, Mobility, Smart Integrated Networks


Integrated smartly controlled energy networks have the potential to deliver significant reductions in carbon emissions, improve air quality and reduce energy costs for end-users across the world. This paper introduces a novel methodology for the development of integrated thermal, power and mobility 5th generation (5G) smart energy networks.

Economic feasibility of booster heat pumps in heat pump-based district heating systems

Applied Energy, Volume 155, 15 July 2018, Pages 921-929
Authors: Poul Alberg Østergaard, Anders N. Andersen

Key words: energyPRO, Energy system simulation, Low-temperature district heating, 4th generation district heating, Heat pump, Groundwater source, Ambient air source, Seawater source

This article uses energyPRO to analyse three low-temperature district heating schemes. District heating is supplied from a heat pump using air, seawater or groundwater as heat sources. Domestic hot water is supplied by booster heat pumps using district heating as heat source or through a heat exchanger. The economic benefit of adding booster heat pumps to cover the domestic hot water demands is assessed by modelling the time-varying operation against the electricity market as well as the time-varying coefficient of performance of heat pumps and grid losses.

A method for assessing support schemes promoting flexibility at district energy plan

Applied Energy, Volume 225, 1 September 2018, Pages 448-459

Authors: Anders N. Andersen, Poul Alberg Østergaard

Key words: Support scheme design, Combined heat and power, CHP, Combined heat and cooling, Heat pump, Trigeneration, Thermal energy store, energyPRO

Flexible District Energy plants providing heating and cooling to cities have an important role in the transition to a renewable energy system. However, often electricity prices do not create sufficient feasibility for these to be installed thus calling for support schemes. The societal resources dedicated to support should be minimised while ensuring the establishment of an adequate amount and right ratio between these units.

This paper presents a method for determining the capacities different support schemes will promote as a function of dedicated resources.

Small-scale combined heat and power as a balancing reserve for wind – The case of participation in the German secondary control reserve

International Journal of Sustainable Energy Planning and Management, Vol 4, 27 Feb 2015

Authors: Peter Sorknæs, Henrik Lund, Anders N. Andersen, Peter Ritter

Key words: Combined heat and power, German secondary control reserve, Integration of intermittent renewable energy sources, Grid balancing

Increasing amounts of intermittent renewable energy sources (RES) are being integrated into energy systems worldwide. Due to the nature of these sources, they are found to increase the importance of mechanisms for balancing the electricity system. Small-scale combined heat and power (CHP) plants based on gas have proven their ability to participate in the electricity system balancing, and can hence be used to facilitate an integration of intermittent RES into electricity systems. Within the EU electricity system, balancing reserves have to be procured on a market basis.

This paper investigates the ability and challenges of a small-scale CHP plant based on natural gas to participate in the German balancing reserve for secondary control.

From Electricity Smart Grids to Smart Energy Systems – A Market Operation Based Approach and Understanding

Energy, Volume 42, Issue 1, June 2012, Pages 96-102

Authors: Henrik Lund, Anders N. Andersen, Poul Alberg Østergaard, Brian Vad Mathiesen, and David Connolly

Key words: Smart grid, Smart energy systems, Large-scale integration of wind and solar, Electricity market, Flexible Combined Heat and Power production (CHP)

The challenge of integrating fluctuating power from renewable energy sources in the electricity grid by the use of smart grids cannot be looked upon as an isolated issue but should be seen as one out of various means and challenges of approaching sustainable energy systems in general. Therefore, electricity smart grids must be coordinated with the utilisation of renewable energy being converted into other forms of carriers than electricity including heat and biofuels as well as energy conservation and efficiency improvements.

This article illustrates why electricity smart grids should be seen as part of overall smart energy systems and emphasises the inclusion of flexible CHP production in the electricity balancing and grid stabilisation. Furthermore, it highlights some recent developments in the Danish electricity market operation.

System and Market Integration of Wind Power in Denmark

Energy Strategy Reviews, Volume 1, Issue 3, March 2013, Pages 143-156

Authors: Henrik Lund, Frede Hvelplund, Poul Alberg Østergaard, Bernd Möller, Brian Vad Mathiesen, Peter Karnøe, Anders N. Andersen, et al. 2013: .

Key words: Wind power, Wind power integration, Wind power cost, Energy system analysis, Electricity markets

Denmark has more than 10 years of experience with a wind share of approximately 20 per cent. During these 10 years, electricity markets have been subject to developments with a key focus on integrating wind power as well as trading electricity with neighbouring countries. This article introduces a methodology to analyse and understand the current market integration of wind power and concludes that the majority of Danish wind power in the period 2004–2008 was used to meet the domestic demand. Based on a physical analysis, at least 63 per cent of Danish wind power was used domestically in 2008. To analyse the remaining 37 per cent, we must apply a market model to identify cause–effect relationships. The Danish case does not illustrate any upper limit for wind power integration, as also illustrated by Danish political targets to integrate 50 per cent by 2020.

Future Power Market and Sustainable Energy Solutions – The Treatment of Uncertainties in the Daily Operation of Combined Heat and Power Plants

Applied Energy, Volume 144, 15 April 2015, Pages 129-138

Authors: Peter Sorknæs, Henrik Lund, Anders N. Andersen

Key words: Electricity market, Balancing services, District heating, Combined heat and power, CHP, Solar heating, energyPRO

The higher capacity of intermittent RES increases the importance of introducing flexible generation units into the electricity system balancing. Distributed district heating plants with combined heat and power (CHP) can provide this flexibility. However, in electricity systems with a high penetration of intermittent RES, CHP units are currently experiencing decreasing hours of operation, making it likely that existing CHP capacity will be phased out from the energy system. Furthermore, when the plants provide balancing for the electricity system, the complexity of their daily operation planning is increased. This article analyses and discusses how these units can improve their economic feasibility by providing balancing services to the electricity system, benefitting both each individual plant and the system as a whole.

Comparing electricity, heat and biogas storages’ impacts on renewable energy integration

Energy, Volume 37, Issue 1, January 2012, Pages 255-262

Authors: Poul Alberg Østergaard

Key words: Energy systems analyses, Renewable energy integration, Energy storages, 100% renewable energy systems, energyPRO

This article takes its point of departure in an all-inclusive 100% renewable energy scenario developed for the Danish city Aalborg based on wind power, bio-resources and low-temperature geothermal heat. The article investigates the system impact of different types of energy storage systems including district heating storage, biogas storage and electricity storage. The system is modelled in the energy systems analyses model energyPRO with a view to investigating how the different storages marginally affect the amount of wind power that may be integrated applying the different storage options and the associated economic costs. Results show the largest system impact, but also most costly potential are in the form of electricity storages.

Conditions for aggregation of CHP plants in the UK electricity market and exploration of plant size

Applied Energy, Volume 88, Issue 11, November 2011, Pages 3930-3940

Authors: Aikaterini Fragaki and Andersen, A.N

Key words: CHP aggregation, Cogeneration, Thermal store, energyPRO

Combined heat and power (CHP) plants with thermal stores may be suitable for sustainable energy production and the accommodation of fluctuating renewable energy sources. At the moment, in the UK, only a few CHP plants have thermal stores. Previous research has shown that thermal stores can improve the economics of CHP plants in the UK under the current market conditions. However, currently, it is only beneficial for CHP plants to sell their electricity to a third party, a Licensed Electricity Supplier, rather than to sell it directly to the power exchange market at prices which are much higher. If CHP plants aggregate, direct access to the power exchange market can become economically viable hence there is the possibility that thermal stores could further improve the economics of CHP plants under an aggregated electricity dispatch. This work firstly explains the conditions under which such plants could aggregate and act as a large power plant in the UK market, and secondly explores the most economic-size of gas engine and thermal store, in the case of aggregation, using energyPRO software and Excel spreadsheets.

Electricity market auction settings in a future Danish electricity system with a high penetration of renewable energy sources – A comparison of marginal pricing and pay-as-bid

Energy, Volume 36, Issue 7, July 2011, Pages 4434-4444

Authors: Steffen Nielsen, Peter Sorknæs, Poul Alberg Østergaard

Key words: Electricity market, Auction systems, Renewable energy scenarios

The long-term goal for Danish energy policy is to be free of fossil fuels through the increasing use of renewable energy sources (RES) including fluctuating renewable electricity (FRE).

The Danish electricity market is part of the Nordic power exchange, which uses a Marginal Price auction system (MPS) for the day-ahead auctions. The market price is thus equal to the bidding price of the most expensive auction winning unit. In the MPS, the FRE bid at prices of or close to zero resulting in reduced market prices during hours of FRE production. In turn, this reduces the FRE sources’ income from market sales. As more FRE is implemented, this effect will only become greater, thereby reducing the income for FRE producers.

This article investigates the two auction settings, to find whether a change of auction setting would provide a more suitable frame for large shares of FRE.

Danish Wind Power – Export and Cost

Department of Development and Planning, Aalborg University, Feb 2010

Authors: Henrik Lund, Frede Hvelplund, Poul Alberg Østergaard, Bernd Möller, Brian Vad Mathiesen, Anders N. Andersen, Poul Erik Morthorst, Kenneth Karlsson, Peter Meibom, Marie Münster, Jesper Munksgaard, Peter Karnøe, Henrik Wenzel, Hans Erik Lindboe

Key words: Wind power integration, Electricity markets, Cost of wind power, Share of unused wind power

In a normal wind year, Danish wind turbines generate the equivalent of approx. 20 percent of the Danish electricity demand. This paper argues that only approx. 1 percent of the wind power production is exported. The rest is used to meet domestic Danish electricity demands.   The cost of wind power is paid solely by the electricity consumers and the net influence on consumer prices was as low as 1-3 percent on average in the period 2004-2008. In 2008, the net influence even decreased the average consumer price, although only slightly.