Energy and the New Reality, Volume 1:
Energy Efficiency and the
Demand for Energy Services
Chapter 8: Municipal Services
L. D. Danny Harvey
harvey@geog.utoronto.ca
Publisher: Earthscan, UK
Homepage: www.earthscan.co.uk/?tabid=101807
This material is intended for use in lectures, presentations and as
handouts to students, and is provided in Powerpoint format so as to allow
customization for the individual needs of course instructors. Permission
of the author and publisher is required for any other usage. Please see
www.earthscan.co.uk for contact details.
This chapter discusses
•
•
•
•
Water supply
Waste water treatment
Solid wastes
Recreational facilities
Energy used to supply water to
southern California
•
•
•
•
•
•
Pumping of groundwater, 1.4-2.2 MJ/m3, or
Diversion,
9 MJ/m3, or
Desalination of seawater, 13-14 MJ/m3, or
Treatment
0.1-0.2 MJ/m3
Local distribution
0.5-2.7 MJ/m3
Provision of bottled water 5600-10,200 MJ/m3
Measures to reduce energy use
in supplying water
• Reduce leakage (30-50% of the water that
enters the supply system in developing country
cities is typically lost)
• Improve pumping system (can reduce electricity
use by 20-40%)
• Reduce waste by end users
• Improve desalination (where applicable)
• Discourage use of bottled water
Wastewater treatment
• The biggest energy savings is through recovery
and use of all of the biogas that is produced from
the anaerobic digestion of sewage sludge
• The pending shortage of P will require eventual
recovery of P from sewage for use as a fertilizer.
Normal procedures are energy-intensive (150
MJ/kgN); extraction from minimally diluted urine
would require much less energy (65 MJ/kgN)
Solid wastes
•
•
•
•
•
Landfilling
Incineration (or pyrolysis or gasification)
Anaerobic digestion
Composting
Mechanical biological treatment (MBT)
- separate recyclable materials (metals, glass,
plastic)
- digest or compost organic materials
Items to consider in assessing the lifecycle energy
balance of different waste management options
• Energy required to collect, clean and sort materials
that are used by secondary production facilities
• Energy used for primary and secondary production
facilities
• Energy value of co-products produced at primary or
secondary production facilities
• Energy costs of disposal of wastes associated with
primary and secondary production
• Electrical or useful thermal energy produced through
incineration
Items (continued)
• Efficiency of methods that would produce the heat and
electricity that are otherwise produced through
incineration
• The efficiency with which wood that is saved through the
recycling of paper could be used to generate heat or
electricity
• The ratio with which recycled fibres can substitute for
virgin fibres in the production of paper
• Capture and emission of methane from landfills
Figure 8.1a,b: Material flows for cases without and with
recycling but without losses
4
mf
m[1-f]
1
E1
m[1-f]
mf
E4
m
2
E2
m
m[1-f]
3
m[1-f]
E3
Source: Boustead (2008, Plastics Recycling – An Overview, Plastics Europe, www.plasticseurope.org)
Figure 8.1c: Recycling (m x f) with losses (F x mf)
Source: Boustead (2008, Plastics Recycling – An Overview, Plastics Europe, www.plasticseurope.org)
Figure 8.2: Recycling of two materials with downcycling
m
1
m
2
m(1-f)
m
m(1-f)+Ffm
3
fm
Ffm
fm(1-F)
7
M-fm(1-F)
4
M-fm(1-F)
M
5
M
6
M
Source: Boustead (2008, Plastics Recycling – An Overview, Plastics Europe, www.plasticseurope.org)
General results
• Recycling of paper and cardboard is clearly and
consistently superior to any alternative option
from an energy point of view
• Recycling of steel and aluminium is strongly
superior to any alternative
• Recycling of glass is preferable to incineration or
landfilling
• Recycling of plastics is preferable to incineration
when cleaning is not necessary, but incineration
with electricity generation can otherwise be
better from an energy point of view
Incineration tends to provide
very little energy because
• Some materials yield little or no energy
• Water that is vaporized subtracts from the net
energy supplied
• The efficiency of generating electricity is low (2030%) because of the need to limit the
temperature and pressure of combustion due to
impurities and irregularities in the waste stream
Figure 8.3 Efficiency in generating electricity from waste
in comparison to generation of electricity from
fossil fuels or biomass
70
BIGCC
Electrical Efficiency (%)
60
50
IGCC
40
30
Fluidized bed gasification
Biomass Combustion
20
Conventional incineration
10
0
0
200
400
600
800
Rate of Waste Input (MWth)
1000
Figure 8.4a Organic carbon flow with landfilling
CH4 (fugitive) to atmosphere
CH4 (collected) combusted to
CO2 , then to atmosphere
CO2 (fugitive) to atmosphere
CO2 from
atmosphere
Plant material
contains C
Landfill
LFG (CO 2 and CH )4
C in landfill
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.4b: Organic carbon flow with composting
CO2 from
atmosphere
CO2 to
atmosphere
Plant material
contains C
Composting
CO2 to atmosphere
C in compost
Application of compost to soil
Increased C in soil
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.4c: Organic carbon flow with anaerobic digestion
CH4 (fugitive) to atmosphere
CH4 (collected) combusted to
CO2 , then to atmosphere
CO2 (fugitive) to atmosphere
CO2 from
atmosphere
Plant material
contains C
Anaerobic
Digestion
Biogas (CO 2and CH )4
C in digestate
CO2 to atmosphere
Application of compost to soil
Increased C in soil
Digestate to landfill or as
landfill cover
C in landfill/cover
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.4d: Organic carbon flow with mechanicalbiological treatment (MBT)
CO2 from
atmosphere
CH4 (fugitive) to atmosphere
CH4 (collected) combusted to
CO2, thento atmosphere
CO2 (fugitive) to atmosphere
CO2 to
atmosphere
LFG (CO 2 and CH )4
(if further degradation)
Plant material
contains C
MBT
C in Residue
Residue to landfill or as
landfill cover
C in landfill/cover
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.4e: Organic carbon flow with incineration
CO2 from
atmosphere
CO2 to
atmosphere
Plant material
contains C
Incinerator
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.5a Fossil fuel carbon flow with landfilling
Plastic
material
contains C
C from fossil
fuels
Landfill
C in landfill
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.5b Fossil fuel carbon flow with MBT
Plastic
material
contains C
C from fossil
fuels
MBT
C in residue
Residue to landfill or as
landfill cover
C in landfill/cover
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.5c Fossil fuel carbon flow with incineration
CO2 to
atmosphere
Plastic
material
contains C
Source: EC (2001b)
Incinerator
C from fossil
fuels
Source: EC (2001, Integrated Pollution Prevention and Control (IPPC), Reference Document on
Best Available Techniques in the Glass Manufacturing Industry,
www.eippcb.jrc.es/pages/FActivities.htm)
Figure 8.6 CO2-equivalent CH4 emission from landfill when some fraction
of the generated CH4 is captured and used to produce electricity, and the
rest is emitted to the atmosphere. A credit for displaced coal-generated
electricity is given here.
30
Gas at 30%, coal at 50%
Net Emission (kg CO2-eq)
25
Gas at 30%,coal at 35%
Gas at 55%,coal at 50%
20
Gas at 55%, coal at 35%
15
10
5
0
-5
0
0.2
0.4
0.6
0.8
Fraction of Escaping Landfill Gas Captured
1
Recreational Facilities
• Indoor skating rinks
• Indoor swimming pools, gymnasia and
recreation complexes
Figure 8.7 Breakdown of energy use in a typical
Canadian indoor skating arena
Ventilation
9%
Lighting
8%
Hot water
8%
Refrigeration
50%
Heating
25%
Total = 1.33 million kWh/yr
Energy saving opportunities for
indoor skating rinks
• Supply required heat from the condenser of the
chiller
• Increase (for new rinks) the thickness of
insulation beneath the concrete floor slab
• Increase insulation of the building and install
enthalpy exchangers
• Install low-emissivity ceiling (to reduce infrared
heat flow to the ice surface)
• Place variable speed drives on brine pumps in
the refrigeration system
Net result
• Easily a 50% reduction in energy use compared
to conventional designs in Canada
• Energy load reduced to the point where a
significant fraction of the remaining load could
be met with rooftop PV
Indoor swimming pools
• Higher relative humidity (RH) will reduce
evaporation from (and evaporative cooling of)
the pool
• However, without high-performance glazing,
condensation problems will occur
• Normally, high rates of air exchange are created
so as to maintain the RH low enough to avoid
condensation problems, which further increases
the energy requirements
A high-performance envelope
• Directly reduces heat loss through the envelope
• Permits maintenance of a higher indoor RH
because inner surface temperatures will be
warmer, thereby reducing evaporative cooling of
the pool
• Permits lower rates of air exchange with the
outside, because RH does not need to be kept as
low
A pool in Germany built to the Passive House
standard is expected to achieve a savings of 60-70%
in total energy use compared to pools meeting the
current German building code
Gymnasia:
Construction to the Passive House standard
results in ventilation airflow alone providing
enough heat to the gym, and allows a single
ventilation system with air flowing from the gym to
the changing rooms (with additional heating due to
the different thermal requirements of the gym and
changing rooms) and then to the outside
Recreation complexes:
• Lend themselves to the use of heat exchangers
and heat pumps to match heat sources and heat
requirements
• Use of just 4 heat exchangers in a complex in
Mexico (involving a hospital, laundry centre,
sports centre with a swimming pool and a family
health centre) would save almost 40% of total
heating requirements