Energy and the New Reality, Volume 1: Energy Efficiency and the Demand for Energy Services Chapter 8: Municipal Services L. D. Danny Harvey [e-mail]

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Energy and the New Reality, Volume 1Energy
Efficiency and the Demand for Energy Services
Chapter 8 Municipal Services L. D. Danny
Harveyharvey_at_geog.utoronto.ca
Publisher Earthscan, UKHomepage
www.earthscan.co.uk/?tabid101807

• This material is intended for use in lectures,
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This chapter discusses

• Water supply
• Waste water treatment
• Solid wastes
• Recreational facilities

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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

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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

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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)

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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

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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

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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

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Figure 8.1a,b Material flows for cases without
and with recycling but without losses
Source Boustead (2008, Plastics Recycling An
Overview, Plastics Europe, www.plasticseurope.org)
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Figure 8.1c Recycling (m x f) with losses (F x
mf)
Source Boustead (2008, Plastics Recycling An
Overview, Plastics Europe, www.plasticseurope.org)
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Figure 8.2 Recycling of two materials with
downcycling
Source Boustead (2008, Plastics Recycling An
Overview, Plastics Europe, www.plasticseurope.org)
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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

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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
  (20-30) because of the need to limit the
  temperature and pressure of combustion due to
  impurities and irregularities in the waste stream

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Figure 8.3 Efficiency in generating electricity
from waste in comparison to generation of
electricity from fossil fuels or biomass
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Figure 8.4a Organic carbon flow with landfilling
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
)
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Figure 8.4b Organic carbon flow with composting
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
)
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Figure 8.4c Organic carbon flow with anaerobic
digestion
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
)
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Figure 8.4d Organic carbon flow with
mechanical-biological treatment (MBT)
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
)
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Figure 8.4e Organic carbon flow with incineration
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
)
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Figure 8.5a Fossil fuel carbon flow with
landfilling
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
)
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Figure 8.5b Fossil fuel carbon flow with MBT
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
)
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Figure 8.5c Fossil fuel carbon flow with
incineration
Source EC (2001b)
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
)
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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.
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Recreational Facilities

• Indoor skating rinks
• Indoor swimming pools, gymnasia and recreation
  complexes

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Figure 8.7 Breakdown of energy use in a typical
Canadian indoor skating arena
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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

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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

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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

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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
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GymnasiaConstruction 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
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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