systems thinking and urban...
TRANSCRIPT
Systems Thinking and Urban Agriculture
Daniel A. Bergquist, PhD
A system is a group of parts which are connected and work together. Systems with living and nonliving parts are called ecosystems(which is short for ecological systems)
What is a system?
Understanding environment and society as a system means thinking about parts, processes, and connections, i.e. interactions
The logic behind the behavior of systems is only visible with a view that takes into account relationships between different parts, and at different scales
-Explanation often found at the next larger scale
Understanding systems…
Energy Systems TheorySystems Theory……..
Important concepts Energy Emergy Transformity Self organizing systems Feedback
and principles 1st Law of Thermodynamics 2nd law of Thermodynamics 3rd law of Thermodynamics Maximum Power Principle (4th law) Hierarchically organized systems (5th law)
EnergyEnergy……..
The ability to cause work…
and WORK is defined as any useful energy transformation
The better the ability to cause work, the higher the share of available energy (exergy)
Energy Transformation
Process
…in most kinds of work, one type of energy is transformed into another with some going into a used form that no longer has potential for further work (entropy)
There are many There are many ““formsforms”” of energyof energy……..
Sunlight…
Wind…
Geopotential energy of elevated water…
Fuel…
Electricity…
Information...
Not all forms of energy Not all forms of energy are equivalent...are equivalent...
sunlight = wind = fuels = electricity
While they can all be converted to heat…one cannot say that calories of one form of energy are equal to calories of another form in their ability to cause work...
• related to concentration
• flexibility
• ease of transportation
• convertibility
QualityQuality……
Energy QualityEnergy Quality……
The concept of quality required a new concept of energy
A concept of energy that recognized that not all forms of energy have the same qualities
A quantitative means of measuring quality….
EMERGYEMERGY - The energy required directly and indirectly to make something
Sometimes called Energy Memory = Emergy
Similar to Embodied Energy
Expressed in energy of the same FORM …usually solar energy
Units = Solar Emergy joules = SeJ
Energy Quality…
The sum of all different forms of energy used up directly and indirectly to make a product or service
InputEme rgy
A Output Emergy = A + B + C
T ransf ormat ionPro ce ss
InputEme rgy
BInput
Eme rgyC
EMERGYEMERGY - The energy required directly and indirectly to make something
Different types of input energies (sources) are converted into solar energy equivalents to enable comparison– the solar energy expended in the past (indirectly) to generate input energies
TransformityTransformity - The energy required directly and indirectly to make something
The ratio of all energies in different forms
(Emergy) to the energy harvested in
transformation processes
Solar Emergy joules/joule
SeJ/J
Energy Quality…
11.5004.40010.00050.000100.000170.000
1.000.0001.000.000.000
100.000.000.0001.000.000.000.000.000
•Solar energy•Wind energy•Organic material•Water – geopotential energy•Fossil fuels•Food•Electricity•Protein•Human services•Information•Genetic information
Typical transformities (Sej/J)Typical transformities (Sej/J)
In what way is Emergy useful?In what way is Emergy useful?Theoretical concept and methodology (synthesis) that enables quantification of…
environmental and human support to economic processes on equal terms, by accounting for all inputs and processes
social and economic unfairness
sustainability of production and consumption
the degree to which systems are dependent on local vs. external, renewable and non-renewable resources
To help understand systems, it is helpful to draw pictures of networks that show components and relationships
With a system diagram, we can carry these system images in the mind. And learn the way energy, materials, and information interact
By adding numerical values for flows and storages, the systems diagrams become quantitative and can be simulated with computers
Visualizing systemsVisualizing systems…
Common symbols in systems Common symbols in systems diagramsdiagrams
Heat Sink
System Frame
Source
Storage Tank
Producer
Consumer
Interaction
Pathway Line
Exchange transaction
Switch
Self-organization and auto-catalytic feedbackA simple self-organizing system including positive feedback:
A produces more of B which in turn produces more of A – e.g. “the squirrel”
Producer ConsumerEnergySource
Feedback
SelfSelf--organizing systemsorganizing systems
Emergy system diagram of semi-intensive shrimp aquaculture in Sri Lanka. Window of attention is set to 1 hectare during one year
System diagram of extensive, milkfish/shrimp/crab polyculture in Panay, Philippines. Window of attention is set to one hectare during one year
1st Law of Thermodynamics
Energy cannot be created or destroyed
Interact ion = Energy Transformat ion
100 J
20 J
108 J
12 J
All energy is accounted for...
Used energy
X
2nd Law of Thermodynamics
In all processes (transformations), someenergy loses its ability to do work
100 J
100 J
4 J
1 J
97 J3 J
St orage
Transformation
We sometimes speak loosely of energy being “used up”whereas what is really meant is that the potential for driving work is consumed, while the calories of energy inflows and outflowing are the same
3rd Law…Absolute Zero Exists
Entropy at absolute zero is zero….
As heat content approaches absolute zero molecules are in crystalline states, and the entropy of the state is defined as zero
(- 273o C)
During self-organization, systems are guided by theMaximum Empower Principle…
Self-organization tends to develop network connections that use energies in feedback actions to aid the process of getting more resources or using them more efficiently...
4th Law...Maximum Empower Principle
Systems maximize power by: 1) developing storages of high-quality energy, 2) feeding back energy from storages to increase inflows, 3) recycling materials as needed, 4) organizing control mechanisms that keep the system adapted and stable, 5) setting up exchanges for needed materials, 6) Contributing work to the next larger system
Maximum EmpowerMaximum Empower
5th Law…All systems are organized hierarchically
Energy flows of the universe are organized in energy transformation hierarchies.
Position in the energy hierarchy can be measured by the amount of energy required to produce something
Energy HierarchyEnergy HierarchySpatial view of units and their territories
Energy networks including transformation and feedbacks
Aggregation of energy network into an energy chain
Bar graph of the energy flows for the levels in the energy hierarchy
Bar graph of solar transformities
(emergy)
Production & Consumption…a simple ecosystem with 3 hierarchical levels
Producer ConsumerEnergySource
Feedback
.
Bio -mass
Plant s
Bio -mass
Wild lif e
Nut rient s
Posit ive Feedback
Nut rient Recycle
Used Energy
Forest Ecosystem
Sunlight
A more complex diagram of a forest...A more complex diagram of a forest...
Diagramming Conventions….
. .
B i o -mass
Plant s
Bi o -mass
Wild l i f e
Nut rient s
Posi t i ve Feedback
Nut rient Recycle
Used Energy
Forest Ecosystem
Sunlight
Goods &Serv ices
Market s
Sales
Purchases
Cut t ing
X
Diagramming Conventions….
Adding more complexity...Adding more complexity...
Renewable Sources
Nat uralEcosyst ems
Agricult ureGreenSpace
Commerce& Industry
Infra-Structure
PeopleGov't
$
Waste
Fuel Goods Services
People
Support Region
Cit y
Bio -mass
Plant s
Bio -mass
Wild li f e
Nut rient s
Posit ive Feedback
Nut rient Recycle
Diagramming Conventions….
A city & support region...A city & support region...
Space and Energy HierarchySpace and Energy Hierarchy
• Depicting spatial hierarchy
• Special characteristics of fossil fuel cities
• Fuel enters at the top and feeds-back
(EP&S 2007:204)
Part 2
Urban AgricultureUrban Agriculture
Sustainable Urban Life Beyond Peak Oil- the potential of urban agriculture
Daniel A. Bergquist
Uppsala Centre for Sustainable Development (CSD Uppsala) Uppsala University & Swedish University of Agricultural Sciences
Why urban agriculture?Why urban agriculture?
If the challenges of climate change and peak oil are taken seriously, it is important to explore alternative strategies to sustain urban life in the future
Urban agriculture may be one such alternativeUrban agriculture may be one such alternative
Multiple aimsMultiple aims
•• Food securityFood security•• Food quality and healthFood quality and health
•• Poverty alleviationPoverty alleviation•• EducationEducation
•• Reconnect to natureReconnect to nature•• AeasteticsAeastetics•• RecreationRecreation
•• Conservation Conservation •• Ecosystem servicesEcosystem services
•• Sustainable developmentSustainable development
Land availability, a basic Land availability, a basic determinant:determinant:
Commecial gardensCommecial gardens
Social projectsSocial projects
KinderKinder--gardensgardens
Roof top gardeningRoof top gardening
Vertical farmingVertical farming
HydroponicsHydroponics
Community gardensCommunity gardens
Note Item UnitData
(units/yr)
Unit EmergyValue
(SeJ/unit)
SolarEmergy(SeJ/yr)
Em$Value
(2000 $/yr)
ENVIRONMENTAL INPUTS1 Sun J 3.46E+10 1 3.46E+10 0.0032 Rain J 3.82E+07 3.02E+04 1.15E+12 0.10
Sum of free environmental inputs (1 omitted) 1.15E+12 0.10
RECYCLED RESOURCES 3 Wood J 8.37E+07 1.35E+04 1.13E+12 0.104 Organic material J 4.37E+09 1.24E+05 5.44 E+14 46.485 Paper J 4.40E+08 2.39E+05 1.05E+14 8.966 Plastic g 5.00E+02 6.38E+08 3.19E+11 0.037 Metal g 2.20E+02 4.75E+09 1.05E+12 0.09
Sum of recycled inputs 6.51E+14 55.65
IMPORTED RESOURCES8 Seeds J 2.00E+05 3.64E+05 7.28E+10 0.019 Municipal Water J 5.99E+06 5.45E+05 3.26E+12 0.2810 Equipment $ 1.28E-01 1.17E+13 1.50E+12 0.13
Sum of imported inputs 4.84E+12 0.41
LABOR11 Labor h 7.20E+01 1.12E+12 8.06E+13 6.89
Total (Y) 7.38E+14 63.06
Emergy Evaluation Table, UAEmergy Evaluation Table, UA
IndicesUrban agriculture
Agro-ecological agriculture
Conventional agriculture
Emergy Investment Ratio (EIR) 0.13 0.07 0.25
Emergy Yield Ratio (EYR) 8.63 15.45 4.94
% Renewable 80 59 34
% Recycled 45 n/a n/a
Environmental Loading Ratio (ELR) 0.24 0.69 1.94
Emergy Sustainability Index (EmSI) 35.43 22.39 2.55
Emergy indices, UAEmergy indices, UA
Potential positive effects (selection)Potential positive effects (selection)
Reduced imports and transportation of food products Cooler microclimates within cities Reduced urban waste generationMore efficient use of local water sources (e.g. storm water) Transformation of urban dumping grounds Elimination of habitats for rodents and mosquitoes etc.Therapeutic and aesthetic effects of contact with natureStronger sense of community (social inclusion and integration)Raised environmental interest among urban dwellersLocalized life styles