Progress on Defining EnvironmentalSustainability

Andrew AllenDarren Robinson

Yong MaoThe Lucas group

Overview

1

• Mass / Energy Balance• The coal / human cycle • Entropy Balance• Application of Entropy Pumps• Local Sustainability• Internal Entropy production to land area relation• Moving away from “local” sustainability

Mass Balance

• Rate of Mass in = Rate of mass out• Total mass in system remains the same

2

Mass Balance

• Rate of Mass in > Rate of mass out• Mass in system increases

Time

3

Energy Balance

• Rate of Energy in = Rate of Energy out• Total energy in the system remains constant

4

Energy Balance

• Rate of Energy in > Rate of Energy out• Energy in system increases

Time

5

Energy Conversion/Conservation

6Total Energy

Energy Conversion/Conservation

• Thermal Energy Increase = Electrical Energy Decrease• Note: TOTAL ENERGY CONSERVED

7Total Energy

Coal/human cycle

Sun: Energy Source

Space: Energy Sink

8

Combustion Combustion

Coal Coal

Carbon in atmosphere

TreesTree solar panel

Coal/human cycle

Sun: Energy Source

Space: Energy Sink

9

Coal Coal

Combustion Combustion

Trees

Carbon in atmosphere

Tree solar panel

Entropy Production

Maximum Entropy

State

Time

10

Entropy Balance

Time

11

Reference State

12

Current Scenario City

13

S

Local sustainability

14

• Energy flow exists attributable to the sun

a. Direct radiationb. Natural work

• Mass flows exist due to natural transport processes

Conditions for local sustainability

�̇�𝑖=�̇�𝑒

1) For all material flows

2) For elements which are not in natural transport processes.

3) Density of material at surface boundary (red):𝜌 ≈ 𝜌𝑟𝑒𝑓

15

Conditions for local sustainability

�̇�𝑖=�̇�𝑒

1) For all material flows

2) For elements which are not in natural transport processes.

3) Density of material at surface boundary (red):𝜌 ≈ 𝜌𝑟𝑒𝑓

15

Conditions for local sustainability

�̇�𝑖 �̇�𝑒

�̇�𝑖=�̇�𝑒

1) For all material flows

2) For elements which are not in natural transport processes.

16

Conditions for local sustainability

• Boundary Conditions are necessary but not sufficient conditions for sustainability

17

• Additionally some sustainable outcomes may not be desirablea. Constrain system

Internal Entropy Production

�̇�

�̇�

18

Internal Entropy Production

�̇�

�̇�

• Assuming an overly idealised steady state process

𝐴𝑆=𝑘𝑠 �̇� 𝑠+𝑘𝐷 �̇�𝐷

18

Area to entropy production

19

Area to entropy production

19

Moving away from local

20

Conclusions

20

• Mass / Energy Balance• Must Be able to close mass cycles either artificially or through

natural cycles• Sustainable habitats must use renewable energy sources • Internal Entropy production is a measure of irreversibilies in our

system and there may be a link between internal entropy production and land area.

• May be possible to assign a minimum internal entropy production per capita ,for a given standard of living, in a given environment.

• Also covered what it means to move away from local sustainability