Transcript Ruralisation – integrating settlements and agriculture to provide sustainability Folke Günther Dept. of Systems Ecology, Stockholm University E-mail: [email protected] URL: http://etnhum.etn.lu.se/~fg/index.htm Is energy cheap? Availabilty for gasoline energy.

Ruralisation – integrating
settlements and agriculture to
provide sustainability
Folke Günther
Dept. of Systems Ecology, Stockholm University
E-mail: [email protected]
URL: http://etnhum.etn.lu.se/~fg/index.htm
Is energy cheap?
Availabilty for gasoline energy at gas station (working time for one kWh)
Energy availability today: About ten times more than 1920
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2
Adaptation to cheap energy: Case 1: agriculture
Improved
wheat
High yield
(seed production with
residual energy)
The farmer
takes care of:
Wild
wheat
Necessary
functions:
Low yield
(seed production with
residual energy)
Pest defence
Seed distribution
Competition with
neighbours
A
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Planting
Pest defence
Competition with
neighbours
Seed distribution
A
q
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Planting
S
o
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l
t
r
e
a
t
m
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n
t
by the use of
fossil fuels
S
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F
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Adaptation to cheap energy, Case 2: settlements
45000
Assume: Four persons living in a house
40000
Food
management:
The
house:
Potential
for efficiency
The car
(Energy
efficiency less than 10:1)
increase
(assuming 15 000 km/yr)
Energy use, kWh/year
35000
30000
Saving potential: about 32 000 kWh/yr
(associated with vulnerability to high energy prices)
25000
Conventional house
(according to ’Byggnorm 80’)
Heavy car (10-12 l/100 km)
20000
15000
Super-isolated house
Light car (5-7 l/100 km)
10000
Assumed local handling, 4000 kWh
Saving
potential:
Saving potential:
about
8 000
kWh/yr
Necessary for
about
respiration, 4000
kWh 6 000 kWh/yr
5000
0
House
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Car
Food
4
Will energy prices continue to be low?
The Hubbert Curve
Maximum finding rate
Found each 5 year period
Ultimately
found
Used
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Different utilisation modes of remaining resources
Rule: You can not use what is not found
∫’found’(x)
dx
∫
A: The Bush mode
≥ ’used’(x)dx
B: Unprobable mode
C: Probable mode
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Will energy prices continue to be low?
The Big rollover
Will this be our gloomy future?
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Why phosphorus?
The constituents of an animal (or vegetable) body:
H With
O gaseous
phases
C — can be
N transported
S by the air
P
Na
K
Ca
10
times more common in the
Without
body
than in the Earth crust
gaseous
More common
phases
—
be
in must
the Earth
transported
crust than in
as solids or
the body
…64 liquids
…64
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The HEAP trap
Hampered
Effluent
Accumulation
Process
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The HEAP trap
H ampered
E ffluent
A ccumulation
P rocess
Q
J
kQ
(stored amount)
J
Q
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J=kQ
(leakage)
10
Linear flows
STORAGE EXHAUSTION:
P extraction horizon: about 130 years
(at current energy price)
Increasing energy use per unit
Increasing energy price
Actual extraction horizon: Unknown
Import of
nutrients
compensates
export of
produce
HEAP:
Leakage
equals
import
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HEAP:
Leakage
equals
import
11
Linear flows
HEAP
HEAP
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A
G
R
I
C
U
L
T
U
R
E same
The
amount,
20%
S
need
E to be
imported
T
T
L
E
M
E
N
T
’Balanced
agriculture’:
-- manure is used for
fodder production
About 80% of the
nutrients are
The balanced agriculture
1%
—
settlement
circulated
The leakage from a
normal agriculture
represents about
the turnover
of
About 20%
is exported
This represent the
nutrient turnover of
about 6 persons
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Conclusion 1
About 6 persons are in
nutrient balance with 1
hectare of balanced
agriculture
This means that about 0,2
hectares of such agriculture
can support one individual
without HEAP effects
Provided that the nutrient containing
residues are returned to the agriculture
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Rules for sustainability
1. You can not be dependent on storages
 Neither of energy Solution: Energy flows
 Nor of nutrients Solution: Recycling
2.
Corollary: Food should be produced as
close
as possible
to the consumer
in
You must
have
a supportive
function
to diminish food system energy
on your order
support
system
needs and maximise nutrient recycling
Solution:
capacity
Improve (not just maintain)
the health of your
ecosystem
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The eco-unit
Area: 50 ha for 200 inhabitants
Diversified agriculture
Functional size, pop. about 200
Plant nutriens in food are
returned to agriculture
Orchards
Private gardens
Biological greywater
treatment plant (wetpark)
Clean water is returned to
the households
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Providing most of the human food
and all of the animal fodder
Open ditches
Nutrient reclaim
Landscape diversity
Predator habitat
Lee – planting
Biomass production
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The ruralisation scenario – start point
In this scenario, the following things are supposed:
#A
is
imagination
made
by
a
4. scenario
1.
2.
3.
Instead
They
The city
Furthermore,
have
of
is building
inhabited
thean
they
same
understand
new
knowledge
by decisionmakers
housesthat
on
of limiting
the city
places
who
resources,
is scientist
have
not
where
static,
thethe
At
point,
the
centre
of
the
municipality
old start
capacity
ecology
but
ones
dynamic.
and
to
were
make
the
Old
torn
rules
far-sighted
houses
down,
for are
long-term
they
and
torne
decide
strategic
down
survival
to build
and
decisions
as
new
eco-units
you.
are built.
in
# The
rules
are:
(The
average
life-time
a house
is supposed to be 60 years, which
the
of thefortown.
hasperiphery
a population
of
33 000
gives can
city
a rate of change
of 1,6%)
You
imagine
most
ridiculous
The the
periphery
is the
inhabited
by 3 000 things
But you have to render a statement of the effects
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Ruralisation – after 12 years
With the given rate of change, the centre of
the municipality has a population of 24 000
The periphery is inhabited by 12 000
Local parks replacing the old
houses
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Groups of four
Eco-units
Each group is
inhabited by 800
people
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Ruralisation – after 25 years
At this stage, the centre of the municipality
has a population of 12 000
The periphery is inhabited by 24 000
Reversed ditching:
5 600 persons
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Underground streams are
brought up to the surface
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Ruralisation – after 50 years
At the end of the ruralisation process, the centre of
the municipality has a population of 3 000
The periphery is inhabited by 36 000
Minimal dependency
of fuel
Many characteristics
Area with integrated
of the
Noarea
HEAP-trap
(P/R-ratio,
nutrient
storages are
due to:
retention
agriculture
capacity,–mutualism,
settlements.
Nutrients are
biodiversity)
circulated
 Localised food-system
closing
Population
to those ofdensity
mature ecosystems.
 Use of wind, solar-power
closing to 500/km2
and biomass
… and the decision-makers
are still there..
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The economy of ruralisation
Assumed annual energy cost increase:
Industrial energy: 5%, Renewable energy: 2%
WWT maintenance and energy cost, MSEK/year
6000this calculation, it is not possible to account for
In
changes
of the ’Rollover’ type. Therefore, continuous,
5000
Annual expenditure
differenceare
2 000 MSEK
steady changes of energy
prices
assumed
4000
Very
small5%
difference:
(In
this
case:
annual increase in price for industrial
Increased human
energy,
and 2%
for renewable energy sources)
3000
transport
equals
diminished food
transport
2000
2,000,000,000 SEK
difference
1000
Ruralisation
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
Y e a rs from now
Ruralisation
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Unchanged town
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Conclusions
There is an immediate need for finding strategies
to avoid dependence on storages of:
Energy
Nutrients
For sustainability, these strategies must also
include a supportive behaviour towards the
supporting ecosystems
Regarding these restrictions, the urban
structure common today is
unsustainable
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Conclusions
To avoid dependence on storages of:
Energy — use flows or funds
Nutrients — recycle
This will impose restrictions on distance
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Conclusions
To establish a supportive behaviour
towards the supporting ecosystems:
Adapt to behaviours typical to mature
ecosystems
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Conclusions
All these strategies can be established
in the border of the urban structures
common today
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Conclusions
By advanced undulation of
the borders,
leading to the integration of the
city with its hinterland,
some obstacles to sustainability
may be overcome
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