# Presentation: 540474

## EMERGY & ENERGY SYSTEMS

**Session 2 **
**Short Course for ECO Interns, EPA and Partners**

**Notes:**
In the first session we set the stage, so to speak, for introducing the concept of energy flow through natural and human networks we call systems. As you work through the remainder of these sessions, we encourage you to refer to Odum’s text – Environmental Accounting – for deeper discussion of concepts and more examples with details.

## Energy Language Diagrams

- Boundary definitions
- System components
- Driving forces
- Structure in symbols
- Function in pathways
- Interactions
- Recycle
- Sinks
- The really great thing about energy language notation

**Notes:**
Before we can begin teaching emergy concepts, there is one more skill we need to develop, and that is the skill of adequately diagramming a system.   By committing our concepts of  the energy connections and storages within an ecosystem to paper, we are inviting review of the completeness of our conceptual thinking.  It also allows us to document the mathematical functions we believe govern rates and interactions.
In this session, we will introduce, or review, the concepts of using a particular set of symbols known as the energy systems language, as well as the fundamental thinking process that leads to a complete overview of the connections influencing productivity.

## Boundary Definitions

- Arbitrary
- Defined by problem statement

**Notes:**
The first step in diagramming any system is to define the boundary.  This is an arbitrary decision and is chosen to address an issue being evaluated.  The boundary determines the scale of your study.  This is not a trivial exercise because every one involved in a project has both a scale at which they are most knowledgeable and a perspective on the important components that should be included.  Unfortunately, every one’s components may not operate at the same scale – in time or space.
If you are not familiar with the system you are evaluating, if you have never been to New Jersey for instance and you are trying to complete a regional evaluation of that state, it is worth the time to visit the region.  Completing a preliminary review on the internet will direct you to areas of greater interest (See preliminary tasks outlined in Stateprep.doc).
I will use the Rookery Bay National Estuarine Research Reserve on the southwest coast of Florida to make this first diagram.  The issue of importance concerns the use of government funds to purchase more land for conservation in an area of rapid development already having large areas of public ownership, but with many unique and heavily impacted natural systems.  The question we will aim towards diagramming is this:
How does the value of environmental services and natural areas compare to the value of potential development?

## Boundary Definitions

- X-Y plane – preserve boundary

- X

- Y

- Z

-  Z axis – top soil horizon to tree tops

**Notes:**
The boundary in the z direction will be about 20 cm into the soil and up to the top of the trees.  The shoreline on the seaward side and the upper preserve boundary on the landward side create a boundary in the x-y plane.  This scale contains portions of two watersheds, is larger than a single ecosystem, but not as large as the smallest political boundaries in the state.
For the time scale, we might evaluate average annual flows for the year 2000.  We could also look at long term averages for the years 1990 to 2000.  Usually, when including economic flows in an evaluation, these flows are converted to emergy for the year in question as are the extracted non-renewables (or renewables used at a non-renewable rate).  However, the renewable environmental inputs are averaged over a longer time period.  The resources used to build an economy are better represented by these long term averages since it took a much longer period to build the resources in most cases than a single year’s imports and exports.

## System Components

**Notes:**
If you are diagramming a system you know well, then you only need to “walk through it” mentally to “see” the structure and functions within the systems.  I use these words (structure and function) because many ecologists use these words to differentiate between the actual species or storages in an ecosystem and the service they perform.  In an energy systems diagram these would be called components and pathways. 

Having defined the boundary, make a list of all the components that represent structure within the system.  These would be storages of materials such as water and soil, the main plant communities or species of interest, the consumers and the human structures such as roads or buildings.  Do not list the pathways or functions for these components.  Include inputs that come from outside the boundary – the sun and rain for example, or rivers and purchased fertilizer.

## Energy Diagram Symbols

**Structure**

**Notes:**
We need to digress for a while to talk about the mechanics of systems diagramming.  We will return to this system and diagram it completely, but first let’s talk a little more about the symbols I started showing in the first session.  
A diagram can use simple symbols – some boxes and circles with arrows indicating direction of flow, for instance.  But after a while one box gets confused with another, you have to keep rereading the label to remember what part does what and so on.  But if you have a small set of symbols that have defined actions, principles and math functions, you can build a diagram using a universal language that anyone can follow, just as different notes on different lines are played in the same way by all musicians – theoretically at least.
These are the four main symbols used to represent four different system components.  The consumer represents any part of the process that does not make its own food or feedstock, but that can transform energy or material into another form.  While heterotrophs come quickly to mind, this symbol can also represent a city or a star.  The circle represents a source of energy from outside the boundary. The tank is a storage component, called a state variable in a simulation model.  The bullet shape represents producers, mostly primary. 
We will talk more about these symbols as we introduce other diagramming concepts. 

## Function in Pathways

**Function in Pathways**

- Force or flow – unidirectional

- Diffusion or backforce – no arrows

- O2, CO2

- O2

- CO2

- Water

- Gasoline

- Gasoline

**Notes:**
The function of each component is indicated by a pathway of some kind.  Specific kinds of connecting lines and symbols are used to show the nature of the function, whether it requires other components to make a connection, if the interaction is simple diffusion or a force like a rushing river, and so on.  The next few slides will work through a number of these kinds of connecting pathways as well as internal paths inside each symbol.  The examples provided are very basic.  For a less abridged presentation of various scenarios and the simulated effect, please refer to either Ecological and General Systems (Odum 1994) or Modeling for All Scales (Odum and Odum 2000).
If the input to a tank comes from an outside force of the same material or energy, a simple unidirectional path between source and tank is used. This might represent river flow or electrical current.
If the exchange between the two occurs by diffusion, no arrowheads are used.  This might be used to represent the exchange of oxygen between the atmosphere and the water in a lake. 

## Function in Pathways

**Money**

**$$**

**Energy or material**

**Notes:**
The flow of money in a system is shown using dotted lines.  Money in or out of a system is usually connected with an energy or material flow.  Draw the money line parallel to that path, but flowing in the opposite direction.  The diamond drawn over both lines indicates that these flows are coupled, and therefore the amount of flow in one line is dependent upon the other.  This is not always true and does not appear in all diagrams with money.

## Structure in Symbols

- Producer- Conceptual

**Notes:**
This symbol represents a photosynthetic organism or primary production function. There are many different ways of presenting this symbol in a diagram, all dependent upon the importance of the internal process in completing an evaluation.
 A simplified set of pathways defines key inputs and outflows without showing any internal mechanisms. This version is appropriate whenever the component is part of a larger scale system or when the diagram is not being used to demonstrate simulation mathematics. The main inputs are arranged so that the primary energy inflow enters from the left, the higher quality inputs are shown entering from the top and primary productivity being removed exits to the right.
 This diagram shows paths from sun (R), water (W), and nutrients (N) interacting to push photosynthesis forward. Whatever is not stored within the population or used for metabolic functions leaves as output (O).  If you were interested in oxygen, use of storage (leaves or roots) as food and litter fall, there would be three output lines leading to appropriate destinations instead of just one. 

## Structure in Symbols

- Producer – working model

**Notes:**
This set of symbols shows a common representation of processes within the producer and are appropriate to include whenever simulation of the system is planned, but also when an internal process is being evaluated - the amount of production stored when nutrients are scarce for example.
P - productivity: the interaction of the sun (R), water (W), nutrients (N) and internal resources (E) in the photosynthetic process
S - storage of net production in leaves, trunks, roots, ,etc.
M - energy used in metabolism
A - natural attrition or mortality
O – use of storage in another part of the network

The autocatalytic feedback from the tank to the interaction (E) may not always be present, any number of interactions, both subsidies and interference can be added and metabolic costs and attrition are not always shown as specific paths to track.  Attrition is often recycled into a detrital or nutrient component.

## Structure in Symbols

- Consumer - conceptual

**Notes:**
This symbol represents an organism or function incapable of manufacturing its own feedstock. There are many different ways of presenting this symbol in a diagram, all dependent upon the importance of the internal process in completing an evaluation.
A simplified set of pathways defines key inputs and outflows without showing any internal  mechanisms. This version is appropriate whenever the component is part of a larger scale system or when the diagram is not being used to demonstrate simulation mathematics. The main inputs are arranged so that the primary energy inflow enters from the left, the higher quality inputs are shown entering from the top, either at the interaction symbol on the left or into the top of the hexagon (not shown), and animals or commodities being removed exit to the right.

## Structure in Symbols

- Consumer – working model

**Notes:**
This set of symbols shows a common representation of processes within the producer and are appropriate to include whenever simulation of the system is planned, but also when an internal process is being evaluated - the metabolic cost of increased enzyme action for example.
P - conversion of the raw materials (F) into muscle or commodities (S) using internal resources (E) and other inputs in the conversion process
M - energy used in metabolism
A - natural attrition or mortality
The autocatalytic feedback from the tank to the interaction (E) may not always be present, any number of interactions, both subsidies and interference can be added and metabolic costs and attrition are not always shown. In this case temperature (T) is shown as a subsidy in the production mechanism. However, in the case of trout for example, temperature would be shown as a reproductive interference and the `X' would be replaced by a divisor.
This symbol can also represent a general population of a species or an entire community of consumers, with the state variable S tracking overall population numbers.

## Structure in Symbols

- Storage –simple outflow

**Notes:**
This symbol represents a storage of material or energy inside the boundaries of the system. These storages can be drawn from in much the same way as forces or sources outside the system. These items are placed within the chosen boundaries because their use or abundance are an important factor needed to answer the question of interest. Surface water, soil, money, nutrients, peat, groundwater, heat and aesthetics are examples of storages. The fluctuation of amount stored in a tank can be tracked during simulation of a system network; modelers call this tank a state variable because the quantity at any time is variable in a dynamic system and the changing quantity influences the state of the entire network.
Occasionally you will see this tank straddling the edge of a boundary or outside the boundary as an outside source.  This is intended to show that, while at some time scales the source may be thought of as infinite, at the scale used for the diagram, the source has finite limits.  In the near future, oil may be diagrammed in this way.
There are several pathways that energy or materials use to enter or leave storage. This drain is dependent upon the force (level of energy or material) in the tank.  Think of a milk jug with a hole punched in the bottom.  When the carton is full, the milk comes out with great force, but as the carton empties, the milk begins to trickle.  
We will talk about other drains and inputs as we start talking about interactions.

## Driving Forces

- Components outside boundary – constant flow

**Notes:**
This symbol represents components outside the boundaries of the system that are available in large quantities relative to the bounded system or process - the inputs that keep the system running. In natural systems such as forests or salt marsh, the inputs crossing the boundaries are few in number and not highly concentrated. The sun is an example of this force. The number of outside inputs increases significantly in systems that include human or economic activities. Fuel, fertilizer, money and cultural information are examples of forcing functions in these systems.
There are two main pathways that these forces use to input energy or materials.
 This symbol shown here represents an input that is drawn from only as a system uses it. Extractables such as phosphate or coal are examples of this forcing function if purchased from outside the systems boundary.  Most purchased or manufactured items also enter a system in this way - electricity, fuel, labor and money are other examples.

## Driving Forces

- Components outside boundary - flow limited

**Notes:**
This symbol represents a flow limited source. There is usually an abundance of energy flowing from this source, but only a portion of it can be used by the system during the time that it is present. The energy not used by the first component drawing from it continues to flow and other components can then use a portion of the remaining energy, or the energy leaves the system as dispersed heat. 
The sun is the best example of a flow limited source. Tall plants use what energy they can, dependent upon other limiting factors in their system, and the remaining energy is then available to under story, reflected or absorbed by the earth.  If the energy is not used as it flows by, it is no longer available to be used.  Although this source of energy returns on a daily basis, there is no fixed storage of leftover solar energy to drive photosynthesis once the sun sets.
Wind and tides are other examples.

## Interactions

- Limiting or subsidizing factors

**Notes:**
With the overview on components complete, we will move to ways to illustrate pathways between components.  
If the input to a tank requires transformation to become the same form of energy or material as from the tank of origin, an interaction symbol is used to indicate the reaction or process to convert. Note that the main feed source comes in from the left and the energy or material interacting with the input interacts from the top. This can also be thought of as lower concentrated input drawn from the left and higher quality input on the top. An `X' indicates an input subsidy while a divisor indicates an input interference. However, other mathematical functions can be used for this interaction.

## Interactions

- Limiting or subsidizing factors

**Notes:**

This drain function is increased by another component or force in the system. Human energy used to catch fish is one example. Stress increasing rate of mortality or mining processes used to extract ores are other examples. Any mathematical function can be used for this drain interaction, not just the multiplicative increase.  For example, seagrass acts as a refugia for crabs, and would be diagrammed as a divisor on the drain representing reduced predation.                                                                        

## Interactions

- Sensor

**Notes:**

This box is a sensor and illustrates a flow of energy dependent upon the level of energy or material in the tank, but not decreasing the storage. Perceived aesthetic value is one example of this sensor flow. The higher the desired quantity – acreage, a specific species, diversity or lake water for instance - the higher the flow of information related to the system's beauty. 

## Interactions

**Interactions**

- Fluid transported sources (or any energy or material that flows in proportion to another pathway)

- River water
- W

- Nutrients
- N

- Sediments
- S

- Jw
- Jn
- Js

- Jw= kw*W
- Jn = kn*W*N
- Js = ks*W*S

**Notes:**

When a river or storm water runoff come into a system, they carry many constituents along, either as dissolved solids or as entrained particles.  The amount of these constituents is proportional to the flow of the water input.  To show this connection, or solute concentration, these flows are linked together with an interaction arrow and a rectangle indicating the main carrying force.
The equations illustrate that while the water flow is dependent only upon a proportionality factor (kw), nutrients and sediment are dependent upon the amount of water flowing.  Don’t worry about these proportionality factors or even the equations – they are presented only to illustrate the connection between the water and the materials being transported. 

## Interactions

**Interactions**

- Productivity

- Energy to
- storage

- Energy used to
- pull in more energy

- Autocatalytic feedback

**Notes:**

Any energy that an organism or system uses as feedback to the production function, increasing the total amount of energy the system can use is called autocatalytic feedback.  This might represent the energy used to hunt for food if the component is an animal.  Another example might be the use if assets to obtain more feedstock in an industrial process.

## Interactions

**Interactions**

- Price and coupled flows

- Price determined by outside source

- P

- Price determined by available commodity

- P

- $

- Show money tank
- If accumulating

**Notes:**
Money and economic trade are an integral part of every ecosystem on this planet.  Even natural areas are influenced by trade if only to hold off developers. The most important thing to remember about money, is that it always flows in the opposite direction of the good or service it is paying for. A tank for money storage can be drawn into the system if accumulation of money is occurring.  However, this tank can be omitted and the dashed line shown simply passing through the system in exchange for purchased items.
The diamond used to link the flows indicate that the value of one flow is dependent upon the other.  The circles interacting with the diamonds in this diagram indicate that a fixed price determines both the flow of goods and the money exchanged.  Price is not always included in diagramming a system, and although two ways for price to interact in a system are shown in this diagram, only one usually drives the choice, and therefore, only one is shown in any economic exchange.
The assets shown in the diagram to the right represent accumulation of items that money has purchased.  This could represent the part of businesses and public works that are symbolized by stocks and bonds.  We will talk more about money in future sessions.

## Recycle

**Recycle**

- Feedback from right to left

- recycle pathways

**Notes:**
Few systems are linear.  Most components interact with more than one other item, and most have some kind of recycle – either as material or energy used to control something further back in the hierarchical chain.  Animal feces decomposed and used as nutrients in plant productivity is one example.  Humans purchasing seedlings to increase diversity is another example.
This pathway, or function, is always shown as leading from right to left over the tops of all other components.  This is no longer a path of concentration, but rather one of dispersion to a sub-system lower in the hierarchy where the energy might still be used to do work. 

## Sinks

- Any transformation, interaction or flow has loss

**Notes:**
It is important in diagramming the energy and material flows in a system to remember that all processes follow the second law of thermodynamics.  These pictures illustrate the components that typically exhibit this energy dissipation.
In a diagram, these heat sink lines are normally drawn as very thin lines exiting the bottom of the diagram where the larger arrow and lines indicate a system heat sink.  Occasionally, if a diagram is complex and having all of these lost energy pathways makes it difficult to identify key pathways of primary flow, these internal lines can be omitted.  However, the arrow at the bottom of the diagram should never be omitted in an energy diagram. 

## Process Box

- “Black” box approach
- or
- Show detail in another diagram

**Notes:**
When there is a sub-process within your system that either needs more detailed illustration or for which the details are unimportant, use a simple rectangle to represent. If the only thing that is important is to recognize that flows are entering or leaving a particular process, using a rectangle simplifies the diagram.   Engineers often refer to this as a “black box approach”.  If the sub-process is important but requires so much detail that it would detract from the larger picture being presented, draw another diagram on another page with this box as the boundary.  

## Components

**Notes:**
Now that you have a basic understanding of each symbol, shift focus back to the system we started to diagram.  Using the four basic symbols (producer, consumer, storage and source) put a symbol next to each item on the list.  Note that some of these items are both storages within the boundaries and inputs from outside as well.  
After you have set up a few diagrams, you will be able to skip this step, but until you are familiar with the symbols this step is very useful.  Using this method, we know we will need 7 producers, 14 consumers, 12 storage tanks and 12 outside sources.

## Order of Concentration

- Increasing concentration or quality

**Notes:**
The first step in committing the system to paper is to draw a rectangle indicating the boundary and arranging the sources around the outside of this box.  Just as we show the chain of connections moving from left to right as transformations occur, so too are the sources arranged.  This diagram shows some generic categories in the order of increasing transformities or increasing energy concentration and can be used as a guideline for all diagrams.

## Complex Diagram

**Notes:**
Use a large piece of paper and pencil for your first diagram, because you will need some room around each component to draw in all the connections to other components and you will likely want to erase or move things as you go.  Arrange your external inputs around the outside of the rectangular box that designates the boundary of the system.  This slide shows the relative placement for the sources listed for this particular system.
Note that I have aggregated all human activity into a single source – humans.  I have added a generic input called goods and services to account for money coming into the system.  I have split funding into private and government.  Humans may have different motives for entering the system (scientific research versus recreation, for example), but the impact is the same.  Funding from different sectors, on the other hand, will have different effects because of the policy used to distribute.  Goods and services enter almost all modern systems even natural areas, through recreational use or government management for instance.

## Complex Diagrams

**Notes:**
This is a lot to keep track of.  You might want to try drawing all the connections from these components in an attempt to uncover all the interactions operating within the system.  This type of thinking exercise helps you to envision cause and effect relationships you may not have completely thought through before.
However, for our purposes, we will attempt to aggregate this complex diagram prior to identifying pathways, although I encourage everyone to at least once attempt to finish a diagram with this complexity.  We will combine some of the structure without losing the ecological value of any individual item or components more critical to evaluating our issue of concern.

## Aggregation of diagrams

- What to lump and what to leave?
- Don’t lose important components – combine
- Remember the question
- How does the value of environmental services and natural areas compare to the value of potential development?

**Notes:**
Aggregating does not mean removing any component from the system.  It refers to combining components and using either average data or data from the dominant entity to evaluate the system.  This data can be weighted for population percentages for example.
The important consideration in aggregation is to emphasize those components of highest priority in answering the original question.

## Aggregation of diagrams

- Sun, rain, runoff, tides/waves
- Water (groundwater, surface water)
- Saltwater community (mangroves, salt marsh, salt, oyster reefs, vegetated marine, sediments, organics, detritus, inverts)
- Terrestrial communities (xeric, hammocks, cypress, marsh, sediments, organics, detritus, inverts)
- Development (boaters, scientists, private holdings, nature lovers, hunters/fishers, pesticides, nutrients)
- Fish (adults, juveniles)
- Birds
- Goods & Services
- Funding

**Notes:**
With that in mind, the components for this system have been aggregated to show the three main land use categories in contention, two key consumers that both attract development and that are most affected by human impacts and finally, the fresh water necessary to support life.  The outside inputs have been aggregated into the environmental resources supporting the natural areas attracting immigrants, a single generic input of goods and services and the funding used to support the preserves and other conservation areas.  Compare the list on the left (aggregated components) and the list we started with – not much has been left out.

## Aggregation of diagrams

**Notes:**
You can see that even at this level of aggregation the diagram has many pathways to keep track of.  Whenever possible, use color to distinguish between different pathways – blue for water for instance.
In this diagram I have used green to indicate the positive feedback the development has on natural vegetative communities.  This represents activities to conserve, protect or restore natural areas and wildlife, for example.  I have used red to indicate feedbacks that are detrimental to the environment.  These might include loss of habitat from gardening chemicals or excess fishing.
This diagram shows outside funding, such as government grants, as the driving force for positive feedback.  There is actually a significant portion of funding that comes from local residents interested in preserving the natural beauty of their community, and because we have drawn the boundaries at the preserve edges, this too is an outside source.   Depending upon the data uncovered through the evaluation, we may disaggregate this again in the future.

## Diagram Exercise

- Draw a complex diagram of a system you are familiar with
- Formulate a question of importance
- Aggregate to answer the question
- Aggregate once more to an almost linear system

**Notes:**
Remember these basics as you sketch your diagram:
Arrange everything in and around the box in order of concentration from left to right, using the guide on slide 26.
Feedback control or recycle go from right to left over the top of all other components and pathways
Main feed source goes in the left hand side, everything else goes in the top
If the quantity of a component in some way affects a flow without using the component, use a sensor
A flow of one entity cannot go from a tank to a tank with a different entity without some interaction (e.g.. Water cannot flow into a chemical tank without being converted to that chemical first)
However, if you are using a rectangle to represent a sub-process, disparate flows can enter the box without interaction.