Transcript 4. Level 4 Renewables_revised

LEVEL 4 RENEWABLE
TECHNOLOGIES TRAINING
4.0 - RENEWABLE
ENERGY TECHNOLOGIES
LEVEL 4 RENEWABLE
TECHNOLOGIES TRAINING
LEVEL 4 RENEWABLE
TECHNOLOGIES TRAINING
Level 3 Re-cap
• Renewable Technologies
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Solar Thermal (Solar Water Heating)
Solar PV (Photovoltaic Cells)
Wind Turbines
Biomass & Bio-fuel Boilers
Combined Heat & Power (CHP)
Biomass Combined Heat & Power
Ground Source and Air Source Heat Pumps
• Information relating to renewable technologies can be found in
ADL2A supporting document Low or Zero Carbon Energy Sources
Strategic Guide. DCLG
LEVEL 4 RENEWABLE
TECHNOLOGIES TRAINING
Solar Water Heating - Collectors
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Flat Plate Collectors
– Thin copper or aluminium absorber sheet, with black coating, backed by coil
of small bore pipework containing fluid, all encased within glass cover
– Fluid circulates through pipework and heat is transferred to the fluid from
the absorber ‘plate’
Evacuated Tube Collectors
– Series of modular glass tubes containing vacuum, mounted in parallel, with
absorber plate and thin pipe.
– Vacuum provides insulation and is reason for greater efficiency
Formed Plastic Collectors
– Consist of tubes or formed plastic panels through which water is circulated
and heated by the sun’s radiation
– Not suitable for year-round use. Only useful when ambient air temperature
is greater than fluid temperature
– Used primarily for heating of swimming pools in warm climates
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Examples of Solar Water Systems
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Solar Water Heating - Collectors
• Flat Plate Collectors
– Pros: Less expensive
Slightly more efficient in warmer weather
Extremely robust
Can be integrated into roof to improve aesthetics
– Cons:
More difficult to install
Once installed difficult to adjust or move
Heavy
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Solar Water Heating - Collectors
• Evacuated Tube Collectors
– Pros: Easier to install
Less weight on roof
More efficient in cold weather
– Cons: More expensive
Less efficient in warm weather
Cheap systems lose vacuum and therefore efficiency
More prone to damage during installation
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Flat Plate Solar
Thermal Collector
Evacuated Tube Solar
Thermal Collector
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Solar Water Heating - Systems
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Compact Systems (Passive)
– The simplest systems are passive solar water heaters
– Most common in regions without extensive periods of below freezing
temperatures
– Water circulates without aid of pumps or controls
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Pumped Systems (Active)
– Use pumps to circulate water (or antifreeze solution) through collectors
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Direct Systems
– “Open Loop” system
– Water heated within system is used directly by the building occupants
– Susceptible to freezing as antifreeze solution cannot be used
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Indirect Systems
– “Closed Loop” system
– Heat transferred from glycol solution by way of heat exchanger
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Typical Passive System
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TECHNOLOGIES TRAINING
Solar Water Heating – Drain Back
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When there is no requirement for heating pumps shut off and fluid does not
circulate and when there is no sunlight
Systems therefore contain antifreeze to avoid freezing during this time
If antifreeze solution is not circulating when subjected to solar radiation,
solution can vaporise, damaging system
Drain back systems slope pipework to allow fluid to drain back into tank
under gravity
This avoids risk of solution vaporising
Also avoids risk of freezing thus negating requirement for antifreeze
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TECHNOLOGIES TRAINING
Photovoltaic Cells
• Monocrystalline Silicon
– Most PV Cells are monocrystalline type.
– Made from single crystal of silicon
– Highest efficiency – Typically 15%
• Policrystalline Silicon
– Made from thin slices cut from a block of silicon crystals
– Slightly lower efficiency – Typically 12%
– Manufacturers claim that cheaper cost outweighs lower efficiency
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Photovoltaic Cells
• Amorphous Silicon
– Thin film made from very thin layer of semiconductor atoms on glass or
metal base
– Lowest efficiency – Typically 7%
– Potential to be manufactured cheaply
• Dye Sensitised Thin Film
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Light sensitive ink printed onto substrate
Low cost of manufacture
Typical efficiencies of 1.2-1.4%-2%
New technology only used in solar power generation plants currently
Supply not sufficient to commercial market currently
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Examples of Solar Photovoltaire Systems
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Wind Turbines
• Power Output is proportional to rotor swept area
• Power Output is proportional to the cube of the wind speed
– Power = 0.5 x Swept Area x Air Density x Velocity3
• Wind turbines are not generally suitable for buildings in built up
urban landscapes as they are not effective when situated close to
other buildings, where wind speeds are generally lower and more
disrupted
• A minimum wind speed is required to initiate the turbines. As such,
average wind speeds for the area of the building should be
assessed before making a recommendation
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Wind Turbines
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TECHNOLOGIES TRAINING
Combined Heat and Power (CHP)
• Parameters required for EPC calculations;
• Heat Efficiency;
Total Annual Useful Heat
– Calculated as;
Total Annual Fuel Energy Input
• Power Efficiency;
– Calculated as;
Total Annual Power Output
Total Annual Fuel Energy Input
• Heat to Power Ratio;
– Calculated as;
Heat Efficiency
Power Efficiency
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TECHNOLOGIES TRAINING
Combined Heat and Power (CHP)
• Building Space Heat & DHW Supplied;
– This is a percentage of the heat and DHW load within the building which
is supplied by the CHP generator
– This value needs to be calculated by undertaking a previous detailed
analysis considering the building heat demand values and patterns.
• SBEM is not a design tool, and as such all figures should be
provided by Consultants for new build projects. For existing
buildings, apply default values if information cannot be found.
• For further information consult the following;
[1] Combined heat and power for buildings. Carbon Trust GPG388.
[2] Small-scale CHP for buildings. CIBSE AM12
[3] Non-Domestic Heating, Cooling and Ventilation Compliance Guide. DCLG
[4] Low or Zero Carbon Energy Sources Strategic Guide. DCLG
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CHP Generator
Micro-CHP Generator
LEVEL 4
HEAT PUMP – COOLING CYCLE
STROMA
Certification
LEVEL 4
HEAT PUMP – HEATING CYCLE
STROMA
Certification
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TECHNOLOGIES TRAINING
Ground Source and Water Source Heat Pumps
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There are 4 main types of Ground Source or Water Source Heat Pump
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Horizontal Closed Ground Loop
Vertical Closed Ground Loop
Vertical Open Loop
Closed Pond Loop
Principle of ground and water source heat pumps is using refrigeration cycle
to extract low level geothermal heat from the ground, groundwater or ponds
Energy (heat) is extracted from the ground or water loop by an evaporator
within the heat exchanger, compressed and then transferred to the heating
system by a condenser
Systems are effective due to stability of underground temperatures
Can be used as preheat for LTHW central heating systems or commonly as
the direct heat source for under floor heating, which requires significantly
lower flow temperatures
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Ground Source and Water Source Heat Pumps
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Horizontal Closed Ground Loop
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Vertical Closed Ground Loop
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Where space is limited, vertical boreholes are prime option
Range from 25m – 150m
Potentially very expensive option
If boreholes are located too close to one another, permafrost can occur in the ground and
render the system inactive and cannot be reversed
Vertical Open Loop
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Polyethylene pipe laid in trenches, typically 1m below the grounds surface
Large areas of free land required, ideally under a large car park for new builds
Mixture of water and glycol used as flow medium
Most cost effective method
Only cost effective if ground water is available and plentiful
Ground water is used as heat transfer medium and pumped through system
Closed Pond Loop
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No adverse impacts on aquatic system due to closed loop
Makes use of heat transfer from water and ground if achievable with body of water being
primary source
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Horizontal Closed Ground Loop
Coil (or Slinky)
Costly borehole digging rig
Closed Pond Loop Coil
Borehole pipework installation
Packaged Systems
Unitary Packaged Units
• Indoor and outdoor components in self-contained
‘unitary’ package.
• Installed as ‘through the wall unit’.
• May be reversible heat pump.
• May have electric resistance heater.
Packaged Systems
Individual Split Systems
• Also referred to as ‘split packaged units’.
REFRIGERANT CIRCUIT
HEAT
REJECTION
COOLING
REFRIGERANT CIRCUIT
HEAT
REJECTION
COOLING
INDOOR UNIT
OUTDOOR UNIT
Packaged Systems
Multi-Split Systems
• Also referred to as ‘multi-split packaged units’.
REFRIGERANT
CIRCUIT
HEAT
REJECTION
DISTRIBUTION PIPES
MULTIPLE
INDOOR UNITS
SINGLE or MULTIPLE
OUTDOOR UNITS
Packaged Systems
Variable Refrigerant Flow (VRF) Systems
• Allows variable control of different branches.
REFRIGERANT CIRCUITS
(CAN HAVE VARIABLE FLOW)
HEAT
REJECTION
REFRIGERANT
CIRCUIT
BRANCH CONTROL
MANIFOLD
MULTIPLE
INDOOR UNITS
SINGLE or MULTIPLE
OUTDOOR UNITS
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compressor
from energy source
condenser
to the heating system
return from the
heating system
expansion valve
Horizontal Closed
Ground Loop
Vertical Closed
Ground Loop
to energy source
Heat Pump system
Vertical Open Loop
Closed Pond Loop
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Air Source Heat Pumps
Centralised Systems
Distributed Heat Pump Systems
DRY AIR COOLER
HEAT REJECTION
Water loop/reversible heat pump systems
• Individual reverisble water-to-air heat
pumps linked to common heat injection
boiler and heat rejection cooling tower.
• Also known as ‘versatemp-type’
system.
BOILER
HEAT
INJECTION
HEAT EXCHANGER
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TECHNOLOGIES TRAINING
Heat Pump system
and its end uses
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TECHNOLOGIES TRAINING
ANY QUESTIONS
OR FEEDBACK