Background lectures Flashcards
What is Material Flow Analysis
Material flow analysis (MFA) is the systematic assessment of the flows and stocks of materials within a system defined in space and time.
Which laws are used in MFA?
1st Law of Thermodynamics: Quantity of energy during transformations stays the same (energy input = energy output)
2nd Law of Thermodynamics: Quality of energy decreases during transformations (entropy increases)
What can MFA be used for?
- Early recognition of problems and opportunities
- Priority setting (what is important? what comes first?)
- Design of products, processes, systems
At what levels can MFA be used?
Global National Regional Local Company Process
How can the growth of anthropogenic metabolism mainly be explained?
By cultural and social evolution (language, technology…)
In technology we are using a lot more different materials today that we did fx 20, 50 and 100 years ago.
What is the vision of MFA?
Addressing sustainability in a socio-metabolic framework.
- The socio-economic metabolism shapes the quality of life (services provided by stocks), generates demand for resources , releases waste , and sets boundary conditions for environmental impacts
- The existing socio-metabolic system is not sustainable (limited resources + environmental sinks ) –> requires a better understanding of the entire system to inform a sustainable transformation
Why are MFA using activities (and not functional units) as a starting point?
- People in all communities, regardless of social, cultural, technical, or economic development, have certain basic needs –> Functional units can become obsolete, basic needs remain.
- An activity is defined here as a system that includes all the processes, goods, and substances needed to satisfy these needs.
- -> A system has multiple functional units which are related through material and energy flows or limited resources (land, materials, energy…).
- Sustainable development then becomes the task to develop systems (incl. technologies, social structures, lifestyles, rules, etc ) that allow us to satisfy our needs within a framework of available resources and limited sinks for pollutants.
- -> Functional units (or products) are regarded as parts of larger systems
- -> Optimization of parts ≠ optimization of system
Dilemma:
- Product LCA: optimization of individual products, but not of region.
- Regional MFA: optimization of region, but not of individual product.
What is included in metabolism of activity “to nourish” expressed with the formula M = f (N, R, T)?
M: Metabolism
N: Need for food (diet)
- -> physiological need (healthy nutrition)
- -> cultural need (social stance, rites, eating habits…)
R: Resource availability
- -> local resources (soil, climate, water)
- -> external resources (import of food, energy, water…)
- -> population (people sharing same resources)
T: Technology
- -> agriculture, irrigation, fertilizers…
- -> food processing, conservation, distribution
- -> cooking
What are the most relevant substances in the activity “to nourish”?
Carbon, Nitrogen and Phosphorus
Why is the carbon cycle relevant?
- Carbon forms the structure of all life on the planet
- -> ca. 45% of the dry weight of all living organisms - Carbon cycle approximates Earth s energy flows (natural, human, industrial)
- -> plants transform radiant energy into chemical energy (biomass, e.g., sugars, starches…)
- -> this biomass (recent and fossil) supports food chains in natural and industrial ecosystems - Carbon forms two of the most important greenhouse gases (CO 2 and CH 4)
- -> without greenhouse effect, Earth s average temperature would be -33 degree C
- -> too much greenhouse effect starts warming the Earth further
Where do we find the biggest carbon reservoir on the globe?
The carbon reservoir in the ocean is 20-50 times larger than the terrestrial and the atmospheric carbon pools.
–> Shifts in abundance of carbon among the major reservoirs will have a much greater significance for terrestrial biota and atmosphere than for the ocean.
This means that the ocean is a big carbon sink which also means that we depend heavily on a poorly understood
carbon sink that effectively removes CO 2 from the atmosphere.
- Without this sink, global warming would drastically accelerate.
A better understanding of the global carbon cycle is therefore a vital part of managing global climate.
- Carbon dynamics of oceans are of particular interest
Give two explantions for the ocean being the biggest carbon sink on earth.
Solubility pump (CO2 is more soluble in cold water, which sinks in Arctic and Antarctic)
Biological pump (about a quarter of the marine primary production sinks to deeper water)
Why is the nitrogen cycle important right now?
- Eutrophication of aquatic ecosystems from fertilizers (62 TgN y–1)
- Nitrous oxide: greenhouse gas and stratosphere depleting substance
Mention primary nitrogen sources on land and in the ocean:
On land: mostly fertilizer production (Haber-Bosch process)
In the ocean: mostly biological but unknown fluxes of fertilizers from land
How do nitrogen cycling regulates CO2 and what limits nitrogen fixation?
The Redfield Ratio: C:N:P = 106:16:1
Nitrogen needs to be taken up by nitrogen fixation to allow CO2 uptake!
What limits N2fixation?
–> Iron: Iron fertilization experiments
What is the definition on “To Clean” in MFA?
The activity to clean is defined as the separation of unwanted goods (e.g., dirt, grease, sewage) from wanted goods (e.g., shirt, metal, water).
Includes all processes and goods used to preserve the health of people and to protect the environment from hazardous substances. (Waste Management)
