The event focused mainly on the opportunities, challenges and new solutions offered by district heating and cooling networks.
According to European heat pump association (EHPA) 75% of district heat in Europe comes from Combined Heat and Power (CHP) units. The remaining 25% is based on the production of heat from renewable energy resources.
District heating networks are not very common in the UK. According to a summary of data collected by the Department of Energy and Climate Change (DECC) in 2013 there were 1,765 individual district heating networks in the UK. As shown in the figure below a district heating scheme comprises a network of insulated pipes used to deliver heat, in the form of hot water or steam, from the point of generation to an end user.
Professor Tony Roskilly from Newcastle University gave a brief introduction to the Joseph Swan Centre for Energy Research, doctoral training centres and other collaborative research centres. The Swan Centre is part of the Sustainable Thermal Energy Management Network. Roskilly provided an overview of current research carried out at Newcastle University. The current research projects include, Biofuel Micro-Trigeneration with Cryogenic Energy Storage, Building Management and Energy Demand and Low Grade Heat Driven Adsorption-Linear-Expander Cycle for Cogeneration of Power and Refrigeration.
Prof Swithenbank of Sheffield University presented on how district heating matters, his topic was extended beyond the issue of district heating alone to consideration of the broader subject of the energy future and the critical role therein of CHP. The discussion thus included; energy sources, energy conversion, energy applications, and potential energy business opportunities. Swithenbank summarised the idea behind this philosophy by using a phrase;
“If you do not know where you are going, you may never get there!”
However, in the short term there will be a growing fraction of fracking gas used for CHP, and a reducing fraction of coal used for power generation. In the medium term, the viable route for low carbon power and products is carbon capture via oxy-fuel combustion with underground carbon dioxide storage (CCS).
Prof Swithenbank iterated that as the fuel source for power generation moves from coal to ‘fracted’ gas, the opportunity has arisen to use a network of smaller power stations with a more efficient thermodynamic cycle based on gas turbine technology, and the example presented is one known as the Allam cycle.
Nevertheless, as with all thermal power cycles, low grade heat is still available for district heating. The Allam cycle is a recuperative gas turbine cycle, which uses the basic Carnot principle. This is that the cycle expansion and compression stages should be as near isothermal as possible, and that their temperatures should be separated as far as possible.
The system is much simpler than the Combined Cycle Gas Turbine (CCGT) and its performance potential of achieving a target net efficiency of 59% including carbon capture is particularly noteworthy. This high efficiency is achieved by compressing the LNG, oxygen and recycled carbon dioxide as liquids and reheating the gas flow before it passes through the combustor to the turbine.
The work needed to compress a liquid is very small compared to the power needed for a compressor to compress the same flow of gas through the same pressure ratio. Thus the power output and engine efficiency is increased dramatically.
Joel Cardinal Head of Energy and Sustainability at the University of Warwick discussed the new heating network at the University of Warwick including the use of novel innovations and Organic Rankin Cycle (ORC). His presentation is summarised as follows.
- Perfect match to enhance thermal storage.
- Can make heat network projects achieve financial closure.
When ORC and steam generation can be viable:
- District CHP system is electrically led rather than heat led.
- CHP operates in an island mode with no grid electricity available on the site.
- CHP or other equipment does not already make use of reclaimed flue heat
What could change the market:
- Further technology development to increase versatility (90°C cooling) for smaller thermal input ORC.
- Better technical and maintenance integration for ORC and steam technologies (reduced complexity).
- Compressors will be developed to be compact and aims to minimise or eliminate the use of oil. The compressor efficiency will be improved with isothermal compression or multi- stage compression.
- The future heat exchangers will be compact with high performance. The fan and heat exchanger combination will be integrated.
- There is great potential for innovative cooling technologies such as, micro-emulsion, electrochemical compression and thermoelastic to replace the conventional vapour compression cycle systems.
SIRACH networking Carole Bond, Carbon Data Resources.
Participants were initially asked to discuss amongst themselves what had stood out for them in the morning’s presentations.
Some reflected on district energy power source and scale issues saying there was a need to ‘stop thinking how to burn things better; don’t burn at all (or as little as possible)’ and that ‘small is better.’ Other participants were struck by the poor ranking of district energy in the UK heating energy market and said they were ‘amazed at the laggard approach of the UK government.’
These new groups were invited to spend some time thinking about the blockages and enablers to district energy that may exist in the system. Investors/buyers were asked to think about what key questions they might have and what issues they would be holding. Developer/suppliers were asked to think about how they might go about describing the benefits to potential buyers and how they might allay any of their fears or issues?
Once both groups had developed their thinking they were asked to share their question, issues and thoughts with each other and then, afterwards, reflect on what happened.
Two key issues repeatedly came up for participants during this dialogue. The first, which was shared by many, was concerned with trust, both in terms of ‘mistrust of what’s being sold’ and ‘mistrust of what’s behind it – does it have substance?’ The second was linked to investment whether investment return horizons ‘most buyers/investors are tied to short- termism (i.e. requiring paybacks of 2 years or less)’, lack of investor confidence ‘if it’s not Government driven, businesses won’t invest in it’ or project feasibility ‘due diligence to address viability – no-one will invest in this.’
Tour of the Byker District Heating Site at Newcastle
Currently nearly 2000 homes are connected to the system along with the local primary school, church, offices and community buildings. The main heat station includes three gas-fired boilers for higher load demand and a one megawatt biomass boiler to deal with the base load on the system which also attracts Renewable Heat Incentives (RHI). This biomass boiler works on wood chip.
An additional one megawatt gas fired Combined Heat and Power (CHP) plant is used during the day when demand is higher. This also has the benefits of exporting electricity to the national grid that would attract a Feed-In Tariff. The additional income from the RHI and Feed-In Tarrif amounts to £250k per annum which helps to reduce the operating cost of the system.
Due to the income from the incentives for the third year in a row it was reported that there has been no increases in the heating charges for the Byker Wall Estate residents. This is despite the fact that domestic gas prices have increased by around 30% in the same period of time.
If you want to experience SIRACH in person, our next SIRACH meeting is scheduled for the 20 January 2016, at Woking, GU21 5JY.
SIRACH will be exploring the topic of - Domestic and Commercial Heating and Cooling - next generation technologies.
On the 20th January the SIRACH Network is visiting Daikin UK's new national training and technology centre in Woking, Surrey. The centre offers industry-leading facilities for hands-on training using the very latest technologies.
The centre features a whole floor dedicated to air conditioning technologies, eight heating training bays, as well as and numerous demonstration rooms. The centre is designed to support the expansion of the air conditioning industry and further encourage the growth of the UK renewables market.
The meeting will focus on the new and developing technologies that could potentially revolutionise the heating and cooling markets. The event will include technical presentations, a facilitated networking session and a tour of the facility.
For more information or to be included on the SIRACH mailing list please register at www.sirach.org.uk or email firstname.lastname@example.org