DISTRICT HEATING & HEAT NETWORKS PRESENTATION

Transcription

1 DISTRICT HEATING & HEAT NETWORKS PRESENTATION Building Solutions Automotive Industry

2 LEARNING OBJECTIVES AGENDA - What is district heating? - Understand basic principles and advantages of DH - Potential heat sources What options are available and the benefits of CHP - Pipe materials and properties Selecting appropriate pipe materials for each individual project - Installation and design What key data is needed to size a pre-insulated pipe network - Biogas / Anaerobic digestion How it works and what feedstocks can be used

3 REHAU WORLDWIDE THINK GLOBALLY ACT LOCALLY 6 CONTINENTS 174 LOCATIONS OVER 15,000 EMPLOYEES

4 REHAU DIVISIONS UNLIMITED POLYMER SOLUTIONS Industry FURNITURE, HOUSEHOLD APPLIANCES, HOSES AND INDUSTRIAL DEVELOPEMENTS Automotive EXTERIOR, WATER MANAGEMENT, AIR MANAGEMENT & SEALING Building Solutions WINDOW AND CURTAIN WALLING TECHNOLOGY, BUILDING TECHNOLOGY, CIVIL ENGINEERING

5 WHAT IS DISTRICT HEATING? DEFINITION Hot water or steam is centrally produced - Transported via insulated pipe network - Connected to individual properties via a heat interface unit - Heat metered - Heat delivered via conventional heating systems

6 WHAT IS DISTRICT HEATING? BENEFITS More efficient to produce energy locally - minimise losses Community based heat sources (e.g. central biomass plant) maximise benefits of renewables Future proof easy to change fuel source Minimise maintenance using one central plant no individual gas checks required

7 USE OF DISTRICT HEATING AUSTRIA COMPARED TO EUROPE Percentage of Houses Supplied by District Heating 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Iceland Denmark Estonia Poland Sweden Slovakia Finland Hungary Austria Germany Netherlands UK Austria: District Heating now nearly 11%

8 WHAT IS DISTRICT HEATING? POTENTIAL BARRIERS Lack of district heating (DH) experience in Austria -> Higher cost to install as perceived as higher risk Lack of awareness of DH and historically poorly conceived schemes Community acceptance required once installed, closed network, no possibility to switch provider Control of tariffs for varying usage from end users

9 HEAT SOURCE OPTIONS OFF-SITE & ON-SITE HEAT GENERATION Waste heat from power stations On-site CHP (fossil fuel or renewable) Energy from Waste (EfW) plants Central boiler (fossil fuel or renewable)

10 COMBINED HEAT AND POWER BASIC PRINCIPLE Traditional power plant Heat losses 70% Energy in 100% Useful electricity 30% Combined heat & power plant (CHP) Heat losses 15% Useful electricity 30% Energy in 100% + Useful heat 55%

11 COMBINED HEAT AND POWER HOW IT WORKS CHP offers the following benefits: - Produces both heat and electricity on site - More efficient use of energy % efficient - Cost savings of 15-40% compared to traditional methods (gas boilers and national grid) - Responsive heat supply heat can be stored Not fuel source dependent - powered either using fossil fuels or renewable sources (such as biomass or biogas).

12 BIOMASS CHP INTRODUCTION Biomass district heating schemes work well because: Biomass boilers are often bulkier than traditional boilers, hence typically located in external plant room, not individual houses Require regular wood chip or pellet deliveries to only one central plant Can be located discreetly on site extremes

13 PRE-INSULATED PIPEWORK OPTIONS FOR PIPE MATERIALS Steel pipe with PU foam Polymer pipe with PU foam Polymer pipe with PEX foam (closed cell - bonded) (closed cell - bonded) (closed cell non-bonded)

14 PRE-INSULATED PIPEWORK STEEL PIPES Advantages: - Strong material resistant to impact damage - Larger diameter sizes available - Capable of withstanding higher flow temperatures / pressure Disadvantages: - Only straight lengths possible - Joints required every 6-12m - High installation costs - Corrosion problems (therefore warning systems are required) - Specialist welding required λ W/mK

15 PRE-INSULATED PIPEWORK TWO TYPES OF PIPE INSULATION CLOSED CELL Closed cell insulation: Advantages: - Excellent thermal insulation - No water ingress if outer jacket punctured - No thermal expansion (self-compensating) - More flexible compared to steel - Long coil lengths possible (less joints) Disadvantages: - Less flexible compared to open cell λ = W/mK

16 PRE-INSULATED PIPEWORK TWO TYPES OF PIPE INSULATION OPEN CELL Open cell insulation: Advantages: - Greater flexibility - Simpler jointing / installation (foam easily removed) - Ideal for confined spaces - Long coil lengths possible (less joints) Disadvantages: - PU closed cell pipes have improved thermal insulation λ = W/mK

17 PRE-INSULATED PIPEWORK HYBRID SYSTEM Possible to combine steel & polymer for large DH schemes. Benefits are: - High temperature / volume steel mains - Cost-effective to install flexible polymer house connections - Can use polymer for smaller mains off spines

18 DELTA T OF DISTRICT HEATING NETWORKS IMPORTANCE OF OPTIMISING THE FLOW / RETURN TEMPERATURES Most flow temperatures are ca. 80 C: - Reduced heat losses - Extends pipe lifespan - Makes a safer network (no steam) Ensure return temperature is as low as possible (high T): Flow / return temperatures (C) Heat load (kw) Pipe size required mm mm mm - Reduces pipe size - > reduce capital costs - Ensures low-grade heat can be used (e.g. Waste heat from CHP)

19 LIFESPAN OF DISTRICT HEATING NETWORKS TEMPERATURE AND PRESSURE With an operating pressure of 6 bar, the service life of the pipes is min. 30 years under the following conditions: - Continuous operating temperature of 85 C - Continuous operating temperature of 80 C, - with 90 C for one month per year and 95 C for 100 hours per year Cross-linked polyethylene (PE-Xa) has the following benefits: Temperature resistant to +95ºC High chemical resistance Oxygen barrier Simple jointing process

20 PRE-INSULATED PIPEWORK SIMPLIFIED STEPS TO DESIGN A HEAT NETWORK 5 kw 7 kw 11 kw 8 kw Biomass boiler 31kW 1. Calculate heat loads for each dwelling 2. Identify heat source & required capacity 3. Pipe sizing (based on flow rates & pressure losses 4. Create bill of materials

21 PRE-INSULATED PIPEWORK ZONING DIFFERENT PARTS OF THE NETWORK Zoning the area: - Based on proximity to buildings - Add the heat loads to form a cumulative for each zone - Size the pipe based on flow rates and pressure losses Example DH network: Zone 1 Zone 4 Zone 2 Zone 3 Zone 5 Zone use Total Heat load Zone 1 10 houses each 5kW 50kW Zone 2 15 houses each 5kW 75kW Zone 3 Primary school 75kW Zone 4 Office 150kW Total heat load is 450kW Zone 5 15 houses each 10kW 100kW

22 PRE-INSULATED PIPEWORK EXAMPLE OF ZONING Zone 1 50 kw 250 kw Zone kw T = 10K Plant Room A B C D E 450 kw 400 kw 100 kw Zone kw Zone 2 75 kw F Zone 3 75 kw

23 PRE-INSULATED PIPEWORK EXAMPLE OF ZONING Zone 1 50 kw 250 kw 90 mm Zone kw T = 10K Plant Room A B C D E 450 kw 110 mm 400 kw 110 mm 100 kw 63mm Zone kw Zone 2 75 kw F Zone 3 75 kw Supply pipe feeding into buildings (32mm)

24 OPTIMAL NETWORK DESIGN BALANCE OF INVESTMENT & OPERATIONAL COSTS The goal should be, optimal network design in order to minimize the total annual costs - sum of investment costs and operating costs, based on a certain period of use! Total costs Cos sts Heat loss costs Investment costs Pumping costs Pipe diameter

25 OPERATING HOURS OF HEAT NETWORKS HEAT DEMANDS PLOTTED OVER ONE YEAR 15 days

26 DIVERSITY OF HEAT NETWORKS IMPACT OF DIVERSITY FACTOR New building Diversity Factor Renovated old building Old building Numbers of connections

27 HEAT NETWORK GEOMETRY STANDARD VS RING MAIN Standard network Ring network Heat source Heat source Heat source Typically a branch network (with a main distribution pipe) is used. However, a ring main offers some benefits for certain projects: - Allows multiple heat sources (future connections) - Flexibility of design - Reliability - Redundancy

28 PRE-INSULATED PIPEWORK INSTALLATION - Cover 600mm minimum 800mm with traffic loads - 100mm of 0.8mm grade sand around the pipe - Pipe positions: - Besides each other - On top of each other Warning tape must be used!

29 PRE-INSULATED PIPEWORK INDIRECT CONNECTIONS Indirect connections: Each house needs a heat interface unit (HIU) off the DH network Individual house metering monitors & control and then bills based on the amount of heat used Smart metering no site readings Typically operated by Energy Supply Companies Direct connections can also be used (no HIUs required) but each property is not isolated, therefore not normally preferred.

30 SPECIAL APPLICATIONS ANAEROBIC DIGESTION INTRODUCTION 1. Cow manure is heated to produce methane 2. Methane generated sent to CHP unit for electrical generation. 3. Excess heat from CHP fed back into fermenter and used for district heating 4. Solid waste reused as fertiliser District heating Solid waste for fertilizer CHP supplies electricity to grid Liquid animal waste Fermenter Biogas powered CHP

31 BIOGAS / ANAEROBIC DIGESTION POSSIBLE FEEDSTOCKS Organic substances which can be used in anaerobic digestion systems: - Animal waste (e.g. cow / pig manure) - Unused crops (leaves, stalks) & grass cuttings - Slaughterhouse waste - Food waste

32 SPECIAL APPLICATIONS - UTES UNDERGROUND THERMAL ENERGY STORAGE In district heating networks with renewable energy sources (e.g. solar thermal), excess heat is wasted in the summer.

33 COMBINING DISTRICT HEATING WITH UTES UNDERGROUND THERMAL ENERGY STORAGE Using underground thermal energy storage with intelligent controls, optimum use of all energy sources can be achieved. The excess heat in summer can then be efficiently stored and then utilised in winter with an increased efficiency. Heat requirement Available solar energy Heat requirement MWh/month Summer storage Use heat in winter 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

34 COMBINING DISTRICT HEATING WITH UTES TYPICAL SCHEMATIC Source: Drake Solar Landing Community Live operation data can be found here:

35 DISTRICT HEATING & HEAT NETWORKS CASE STUDIES Bioenergy village, Effelter, Germany kw Biogas plant - Uses DH CHP system to deliver heat to 36 houses, fire station and restaurant - Additional wood chip biomass boiler for peak demands - System produces 1.1 million kwh/a - CO2 saving of 370,000 kg/a

36 ANAEROBIC DIGESTION CASE STUDY Much Fawley Farm AD plant, Herefordshire - AD plant fed by slurry, maize & silage - RAUVITHERM pipework connects hot water from CHP to chicken sheds - 2,500m of pipework in total (75 UNO & 32 DUO)

37 DISTRICT HEATING & UNDERGROUND ENERGY STORAGE CASE STUDY Braedstrup District Heating & Solar Park, Denmark System description -1,400 homes - DH network owned by community - 6MW system (3,800 MWh/a) Heat sources: - 16,000m² solar collectors - Heat pump - Peak heating through district heating network Heat storage: - 2,500m³ buffer tank(hot water) - 50 PE-Xa probes at 50m deep

38 DISTRICT HEATING & UNDERGROUND ENERGY STORAGE CASE STUDY Solar Storage & District Heating, Crailsheim, Germany System description dwellings, school, sports hall MWh/a with network temperatures flow/return 65/35 C Heat sources: - 7,300m² solar collectors with 5,1MW peak output kw heat pump - Supplementary heating through district heating network Heat storage: - 100m³ high temperature peak load storage (hot water) - 480m³ buffer storage (hot water) - 43,200m³ ground-source probe underground storage (80 PE-Xa probes)

39 SUMMARY - Understand the pros and cons of DH networks and they can be best utilised. - Use the benefits of on-site generation with CHPs to reduce demand on fossil fuels and increase system efficiencies - Selecting appropriate pipe materials for each individual project, based on pros and cons of steel and polymer - Designing a well-sized DH system is vital for ensuring highest possible energy efficiencies and low pressure losses. - Understand how anaerobic digestion works and the potential of producing energy from waste (and reducing landfill)

40 THANK YOU FOR YOUR ATTENTION ANY QUESTIONS? Building Solutions Automotive Industry