Modelling Energy, Consumption and Waste Flows for Cities

Quantification of urban metabolism through coupling with the life cycle assessment framework: concept development and case study(15 page pdf, Benjamin Goldstein, Morten Birkved, Maj-Britt Quitzauand Michael Hauschild, Environ. Res. Lett., Jul. 26, 2013)
 

Today we review a more sophisticated estimate of the ecological footprint of a city using a 3^rd generation urban metabolic model called UM-LCA for short. The model is applied to five cities with different characteristics: Cape Town, Toronto, Beijing, London and Hong Kong and the resulting estimates reveal large differences in per capita contributions to global warming and energy flows, showing once again the destructive outcomes from sprawled cities and private vehicle use such as Toronto and of the relative emissions from residences and industry.

Key Quotes:

 “The contribution of cities to a number of global environmental pressures such as climate change, water stress, biodiversity loss and resource scarcity is recognized to be strong…These pressures will likely increase vastly.. the percentage of urban dwellers worldwide is predicted to swell from 50% currently to 70% of total population by 2050”

“UM [urban metabolism] refers to a broad range of quantitative methods that attempt to conceptualize urban areas as organisms, requiring goods and energy to maintain functionality and support growth, while emitting waste as a byproduct”

"For all of the cities except Beijing embedded mass flows accounted for more than 60% of the total mass flows resulting from the cities’ metabolic activities,”

 “Energy consumption through the cities showed a similar trend, with the embedded energy flows contributing between 48% (Toronto) and 76% (Hong Kong) of the cities’ total life cycle energy requirements.”

“The per capita GWP [global warming potential] for the cities, according to the UM–LCA model, are: 10.2 tons for Hong Kong, 11.2 tons for Cape Town, 12.2 tons for London, 17.2 tons for Beijing and 18.0 tons for Toronto”

“For the wealthier cities, Toronto as an example, the largest contributing factors to the GWP are transport (27%) and building energy (24%), with waste disposal also playing a large role (21%) due to the city’s composting activities that generate methane… GWP from transport stems primarily from the high usage rates of private automobiles in the city”

“Wealthier case cities tend to mitigate air pollution issues through the use of cleaner technologies in energy generation, consistent with the theory that local environmental pressures are inversely related to the wealth of the potentially affected population”

“The conceptual UM–LCA model has the potential to provide an improved assessment tool for urban environmental loading beyond earlier UM methods through inclusion of the environmental pressures embedded in the goods that cities consume and by offering a clear set of communicative indicators.”

Related articles

• Urban Metabolism Group at MIT Releasing Two Books Soon
• Life cycle assessment in support of sustainable transportation
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What Are the Links between Premature Deaths, Air Pollution and Climate Change on a Global Scale?

Global premature mortality due to anthropogenic outdoor air pollution and the contribution of past climate change(12 page pdf, Raquel A Silva, J Jason West, Yuqiang Zhang, Susan C Anenberg, Jean-Franc¸ois Lamarque, Drew T Shindell, William J Collins, Stig Dalsoren, Greg Faluvegi, Gerd Folberth, Larry W Horowitz, Tatsuya Nagashima, Vaishali Naik, Steven Rumbold, Ragnhild Skeie, Kengo Sudo, Toshihiko Takemura, Daniel Bergmann, Philip Cameron-Smith, Irene Cionni, Ruth M Doherty, Veronika Eyring16, Beatrice Josse17, I A MacKenzie15, David Plummer, Mattia Righi, David S Stevenson, Sarah Strode, Sophie Szopa and Guang Zeng, Environmental Research Letters, Jul. 11, 2013)  

Also quoted here: Researchers estimate over two million deaths annually from air pollution (Institute of Physics (IOP) News, Jul. 12, 2013)  

And here: Air Pollution Responsible for More Than 2 Million Deaths Worldwide Each Year, Experts Estimate(Science Daily, Jul. 12, 2013)
 

Today we review a new estimate of the global burden of premature deaths due to ozone and particulate matter 2.5 which total 2.1 million deaths each year due to PM 2.5 and 470,000 due to ozone. Using a different set of assumptions than used previously, the role of air pollution-related climate change from 1850 to present is seen to be smaller than expected with only 3,700 deaths due to this – not to state that future climate change would be greater.

Key Quotes:

"Our estimates make outdoor air pollution among the most important environmental risk factors for health. Many of these deaths are estimated to occur in East Asia and South Asia, where population is high and air pollution is severe."

“around 470,000 people die each year because of human-caused increases in ozone. It also estimates that around 2.1 million deaths are caused each year by human-caused increases in fine particulate matter (PM2.5)”

“a changing climate results in 1500 deaths due to ozone and 2200 deaths related to PM2.5 each year.”

“Very few studies have attempted to estimate the effects of past climate change on air quality and health. We found that the effects of past climate change are likely to be a very small component of the overall effect of air pollution,"

Related articles

• Climate change brings small rise in air pollution deaths
• Air pollution 'an invisible killer'
• Study: Air pollution kills millions each year
• Killer Smog: East Asia, India, Southeast Asia Top Global Air Pollution
• Human-Caused Air Pollution Responsible For 2 Million Deaths Annually
• New Study: Outdoor Air Pollution Kills 2.5 Million Each Year
• Man-Made Pollution Causes Two Million Deaths Every Year
• Air Pollution Estimated To Cause Over 2 Million Deaths Annually
• 2 Million Deaths Yearly Worldwide Linked with Air Pollution
• Air pollution kills more than two million people per year.

How Can Air Pollution Cause Perforated Appendices?

Ambient Ozone Concentrations and the Risk of Perforated and Nonperforated Appendicitis: A Multicity Case-Crossover Study(Gilaad G. Kaplan, Divine Tanyingoh, Elijah Dixon, Markey Johnson, Amanda J. Wheeler, Robert P. Myers, Stefania Bertazzon, Vineet Saini, Karen Madsen, Subrata Ghosh, and Paul J. Villeneuve^, Environmental Health Perspectives. Jul. 11, 2013)

Also quoted here: Smoggy Days May Raise Your Odds for Burst Appendix(Health Day, July 11, 2013)
 

Today we review research conducted from data in a dozen Canadian cities that showed a significant link between short term increases in ground level ozone and the occurrence of perforated appendices – a concern especially for seniors living in urban areas with growing traffic air pollution. The risk increases by 22% for an increase of 16 ppb of ozone over the previous week. The authors caution that ozone may not be the cause but rather a marker.

:
Inflamed appendix removal by open surgery (Photo credit: Wikipedia)

Key Quotes:

“the investigators tracked rates of emergency care for appendicitis involving nearly 36,000 patients treated in 12 Canadian cities between 2004 and 2008.”

"short-term exposure to ambient ozone [in air] was associated with an increased number of hospital visits for appendicitis….the risk for perforated (burst) appendix rose by up to 22 percent with every 16 parts-per-billion rise of ozone in the air over the three to seven days prior to the appendicitis incident”

"highlights a previously unrecognized association between air pollutants such as ozone emitted by burning fossil fuels, and an increased risk for perforated appendicitis," "In very young patients and the elderly, perforated appendicitis can be a very severe condition and even lethal for these vulnerable populations, often due to a delay in diagnosis,"

“The lifetime risk of appendicitis is approximately 1 in 15, and appendectomy for appendicitis is

amongst the most frequently performed operations in developed nations…..In the United States, appendicitis-related hospitalizations contribute to approximately $3 billion in hospital charges annually”

Related articles

• Burst Appendix Linked to Ozone Air Pollution
• Study links appendicitis to air pollution
• Smoggy Days May Raise Your Odds for Burst Appendix
• Top 10 Most Polluted Cities in America
• Well: Air Pollution May Raise Appendicitis Risk
• Well: Air Pollution May Raise Appendicitis Risk

How Can Cities Best Measure Greenhouse Gas Emissions?

What metrics best reflect the energy and carbon intensity of cities? Insights from theory and modeling of 20 US cities?(12 page pdf, Anu Ramaswamiand Abel Chavez, Environmental Research Letters, Jul. 3, 2013)

Today we review a research paper that examines various ways cities use to measure and compare GHG emissions: top down and bottom up- and the advantages or disadvantages of these approaches. The authors conclude that normalizing the output in terms of carbon-energy per unit GDP.

Key Quotes:

“no guidance is yet provided on how to normalize the aggregate GHG emissions computed by the different methods to help cities compare their local energy intensity and carbon intensity features with other cities.”

“a key question that arises is: what metrics best represent the energy intensity of cities at the local or regional scale?”

“The major conclusion of this paper is that a dual approach of GHG accounting for cities, with CIF and a separate CBF, as is being recommended by ICLEI-USA and BSI, demands different metrics. Our modeling of 20 US cities shows the GHGCIF (all metabolic community-wide GHG accounts) are best represented as per unit GDP.”

“Our paper suggests that using the appropriate GHG accounting method (CIF) with the suitable normalization (per unit GDP) is important to better uncover relationships with urban form; the per GDP metric has the added advantage that downturns in the economy are readily accounted for.”

“Our results suggest cities should use GHG per capita metrics for consumption-based accounts and GHG per GDP metrics for the infrastructure-supply chain accounts.”

Related articles

• Reducing GHG Emissions by Shorter Commutes and More Energy-Efficient Homes
• U.S. Community Protocol for Accounting and Reporting of Greenhouse Gas Emissions
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• Maryland governor releases final Greenhouse Gas Reduction Act Plan
• Boulder wants goal of cutting greenhouse gas 80 percent by 2050

Measuring NO2 from Urban Vehicle Emissions with Infra-Red and Ultraviolet Remote Sensors

Remote sensing of NO2 exhaust emissions from road vehicles(93 page pdf, David Carslaw and Glyn Rhys-Tyler, DEFRA Project Reference:332c2011 (City of London Corporation) , 334c2011 (London Borough of Ealing) , May 2013)

Also discussed here: Remote sensing of NO2 exhaust emissions from road vehicles(King’s College London News, Jun. 12, 2013)
 

Today we review research on measuring NO2 emissions from EU standard and diesel vehicles using remote sensors on roadways in London. Results show that while NO2 concentrations have slowly decreased over the last decade due to more stringent EU standards, there has not been a similar improvement in diesel vehicles. For the latter, care must be taken in reducing NO2 that increases in Particulate Matter (PM) are avoided.

Key Quotes:

“Directly emitted NO2 from vehicles behaves like a primary pollutant close to roads and can make a significant contribution to near-road NO2 exceedances of both the annual and hourly mean EU Limit Values.“

 

“Co-linear beams of infrared (IR) and UV light are passed across the roadway into the IR detection unit, and are then focused onto a dichroic beam splitter, which serves to separate the beams into their IR and UV components. The IR light is then passed onto a spinning polygon mirror, which spreads the light across the four infrared detectors: CO, CO2, HC and reference.” 

“Whilst it is possible to analyse trends in NOx and NO2 emission rates using aggregated data from monitoring sites across the LAQN, this roadside sensing technique has the advantage of being able to quantify the variation in NOx and NO2 emissions across the urban road vehicle fleet by vehicle type (e.g. car, LGV, HGV, bus, taxi), fuel type, Euro standard, engine size and vehicle age.”

 

“For passenger cars, emissions of NOx for Euro 5 diesel cars are at an equivalent level to pre-Euro vehicles (i.e. pre 1992 vehicles). Emissions peaked for Euro 2/3 cars but are only about 25% less for Euro 5 cars. “

“diesel cars >2.0l accounted for 36% of total diesel passenger cars measured.”

 

“For diesel cars it has been shown that total NOx emissions, whilst peaking for vehicles manufactured around year 2000, have changed little overall over the past 20 years and in that time new after-treatment technologies have increased the proportion of NOx that is NO2 “

“A brief analysis of ambient trends of NOx and NO2 at 23 roadside and kerbside sites in London over the past 10 years shows that NOx and NO2 concentrations have only decreased by about 1 and 0.5% on average per year, respectively “

 

“only measuring NO and making assumptions about the level of NO2 for modern vehicle technologies could be unreliable and potentially misleading. “

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• How Much Traffic-Related Air Pollution Comes from Vehicle Exhaust?
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Managing Spawl to Produce Sustainable Communities

Can We Have Sustainable Transportation without Making People Drive Less or Give up Suburban Living? (Abstract, Mark Delucchi and Kenneth S. Kurani, Journal of Urban Planning and Development, Jun. 26, 2013)
 

Also discussed here: A Sustainable City With Cars and Low-Density Homes? It's Possible (Eric Jaffe The Atlantic, Jun. 28, 2013)

 
Today we review an article that addresses the biggest challenge to a carbon free society- sprawl, based on long commutes to widespread communities, fostered by the long era of cheap oil and gas. The proposed solution is to aim at small to mid-sized cities (under 100K) which restricts heavy polluting vehicles to the outer ring of the city and conserves the urban populated centre for low speed, less polluting modes of
transportation. 
   

Key Quotes:

^“car ownership is so desirable that any effort to address sustainability must embrace it, rather than defy it.”

 “what's so pernicious about modern sprawl is not the cars themselves, per se, but their "high kinetic energy" — in simple terms, their size and speed.”

“find a way to dramatically lower the kinetic energy of personal travel while sustaining the advantages of personal, self-directed mobility and access to both urban and suburban living. … create two autonomous and universally accessible travel networks: one for fast-heavy vehicles, the other for low-speed, low-mass, transportation modes, including new designs of motorized vehicles.”

“People would live in small city clusters built around a town center replete with stores, offices, schools, public buildings, and parks. Traveling around town, residents would take the "light" road network. They would walk, bike, or drive tiny cars incapable of exceeded 25 mph. There would be no on-street parking at all. The general idea is to promote interaction and accessibility.”

“Conventional cars would travel the "heavy" road network out of town, mostly to commute elsewhere for work or shop at big box stores confined outside the city limits….Multi-family residential buildings would be situated closer to the center, with lower-density single-family units constructed toward the outer fringe. The towns themselves would be limited to populations of 50,000 to 100,000.”

“if the problems of urban sustainability had an easy answer, we probably would have already found it.”

Related articles

• Toronto and the Importance of Municipal Politics
• Persuading People Not To Drive
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Reducing GHG Emissions by Shorter Commutes and More Energy-Efficient Homes

Housing and Mobility Demands of Individual Households and their Life Cycle Assessment(Abstract, Dominik Saner, Niko Heeren, Boris Jäggi, Rashid A. Waraich, and Stefanie Hellweg, Environmental Science & Technology, May 6. 2013)

Also discussed here: 21 Percent of Homes Emit 50 Percent of CO2(Julia Whitty, MotherJones, Jun. 27, 2013)

Today we review estimates of CO2 emitted by the two largest sources in a medium-sized Swiss town: emissions from homes and vehicles. While it has long been known that these two sources account globally for 70% of greenhouse gas emissions, this research looks at grouping within the population and found that larger houses (which makes up about a fifth of the total) and drivers with longer commutes accounted for more than 50% of the total. This suggests that a focus on home and vehicle energy efficiency (or on smaller homes and shorter commutes) would produce the most effective results, to the extent that reducing the emissions of these two groups by 50% would reduce the overall total by 25%.

Key Quotes:

“The energy people use to power their homes and drive their lives accounts for more than 70 percent of CO2 emissions”

“on a midsized community, we found a median value of greenhouse gas emissions of 3.12 t CO₂ equiv and a mean value of 4.30 t CO₂ equiv per capita and year for housing and mobility.”

“Twenty-one percent of the households in the investigated region were responsible for 50% of the total greenhouse gas emissions, meaning that if their emissions could be halved the total emissions of the community would be reduced by 25%.”

”driving factors for large environmental footprints are demands of large living area heated by fossil energy carriers, as well as large demands of motorized private transportation.”

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