# Presentation: 679261

## EMERGY & ENERGY SYSTEMS

**Session 6 **
**Short Course for ECO Interns, EPA and Partners**

**Notes:**
In the last session, we introduced the use of emergy to assess the real wealth of a region and the equity of trade with this region.  We learned how to calculate the emergy to dollar ratio and how this important emergy ratio allows us to directly link environmental resources and services to economic/human systems.  We also showed that economic equity is not the same as emergy equity.  The emergy to dollar ratio is an important final result derived from regional evaluations.

## Evaluating Tangibles

- Natural systems
- Purchased or processed materials

**Notes:**
In this session we will go into more detail about those emergy evaluations that deal with what I will call tangible items and systems.  These are systems where, for the most part, it is easy to evaluate flows in terms of energy and materials.  A forest ecosystem, a banana crop or the processing of phosphate rock into fertilizer are good examples.  These are systems where humans either don’t play a part, or where their influence in easily measured.  It does not include systems where cultural values or information generation have not already been translated into a defined mechanical process.  For example, the kosher method for slaughtering chickens is tangible and can easily be evaluated through  the materials and man-hours required to complete the process.  The translation of religious values into a process has already been done for us.  Evaluating the value of the religion behind the process would not be tangible and would require a more theoretical information evaluation. 
Regional evaluations are for the most part tangible in nature and the case studies presented in this session should be adequate to get you started.  The information storage component for each regional evaluation is not as well defined, but we will talk about this in a later session.
We will be using case studies to give you more experience in reading different kinds of tables and diagrams, to point out where information is coming from and how the studies were set up, and to provide examples of areas where communication of methods might not be clear from the notes or table.  While most of these examples have a paper connected to them somewhere, tables and notes are often presented by others out of context, and consequently, they must have enough information to stand alone without confusion about where data or assumptions have come from.
As always, more information is available in Environmental Accounting (Odum 1996).  For this session, we will be referring to several Tables from Folios 3 and 4.  You might want to pull up the notes on your computer in advance or  print them – Folio 3: Tables 16, 19, 14, 22 and 5; Folio 4: Tables 23 and 16.

## Natural Systems

- Generic
- Folio 3
- Pg. 3

**Notes:**
This generic diagram of a natural system is offered in Folio #3* (available in PDF form on this website).  Walk through the diagram from left to right as I translate this diagram into a verbal description.
In every natural system, there is some source of primary productivity represented here as vegetation.  A certain amount of incoming energy from the sun, wind and recycled materials is converted into biomass storage and the rest is transpired as oxygen and water vapor.  This biomass feeds the animals or becomes part of the soil as it dies.  The animals, being made up of both vertebrates and invertebrates, also consume the organic matter in the soil, and then recycle feces back to the plants to be used as nutrients or become part of the soil as they die.  Their population also increases or decreases dependent upon migratory habits. Rain and runoff are stored in the soil until capacity is exceeded at which point runoff occurs.  Soil water also infiltrates into aquifers dependent upon the geology of the system or is lost to the atmosphere through evaporation determined largely by the wind or is taken up by plants.  This is one perspective on generic systems, but appears to represent mostly terrestrial systems.
Here are some things we could add to make it more generic: a storage of surface water to represent a lake, river, deep wetland or even just ephemeral standing water; a pathway or additional consumer to represent carnivores; the loss of soil and geologic formation from weathering and erosion; tides and waves; and the natural forces that work to manage the system – hurricanes or fire for example. 
The two main points are 1) to draw a diagram that represents the system you will be evaluating and 2) a single, general diagram can be used for many different natural systems.
We will be looking in detail at several representative natural systems.  These have been completed in individual reports, thesis and dissertations with excerpts presented together in Folio #3.

* Reproduced with permission of editors (Brown and Bardi 2001).

## Natural Systems

- Wetlands
- Forested
- Estuary
- Folio3
- Pg 59

**Notes:**
This table presents inputs to a forested estuary, specifically mangroves in Ecuador.  Besides the typical environmental energies, this system is being subsidized by nutrients from local sewers.  This table follows a standard format with the unit emergy and emdollars presented along with raw data and the total emergy for each flow. This evaluation was used to determine the unit emergy for mangrove biomass growth and litterfall receiving this additional nutrient input.  You can tell this because the total emergy in the 5th column (Solar Emergy) for lines 9 and 10 are the same.  This amount, 279 E18 sej/yr, tells us that the total inputs included were determined to be necessary to produce both of these entities and therefore the total emergy is divided by each individual energy to get a transformity representative of each component.  Although this particular table has a round off error, and the renewable inputs included in the total are not spelled out in the notes, the values that are summed to get the total emergy for the system are lines 3, 5, 7 and 8.  Line three, the transpiration, is the single largest emergy value among the items we need to be careful to not double count.
Please remember, if you need to complete a unit emergy evaluation, to provide information about which lines were included in the total emergy value.  In addition, please add a line above the components evaluated stating that the unit emergy ratios are being calculated.

## Natural Systems

- Wetlands
- Marsh
- Freshwater
- Folio3
- Pg 65

**Table19. **Emergy flows supporting subtropical herbaceous wetland, Florida. (Bardi and Brown, 2001)
- Note  Item 		            Data       Units       Emergy/unit    Solar Emergy
-                                                                                        (sej/unit)       E15 sej/ha*yr-1
*Energy Sources*
- 1      Sun 		           4.19 E13  J/ha/yr 	           1 	      0.04
- 2      Wind 		           3.15 E9    J/ha/yr          1496              0.005
- 3      Rain, chemical potential        6.42 E10  J/ha/yr        18199              1.17
- 4      Run-in, chemical potential     2.25 E10  J/ha/yr        51867              1.17
- 5      Geologic input                       2.97 E6    g/ha/yr       1.00 E9            2.97
*Functions (Env. Services)*
- 6      Transpiration (water use )     2.67 E10  J/ha/yr        26928             0.72
- 7      GPP 		           8.54 E11  J/ha/yr          4319             3.69
- 8      Infiltration                              1.82 E10 J/ha/yr         26928             0.49
*Structure (Natural Capital)*
- 9      Live Biomass                        1.00 E11  J/ha            73426             7.38
- 10    Peat                                      3.77 E12  J/ha          183870         693.41
- 11    Water 		           3.94 E10  J/ha            26928            1.06
- 12    Basin Structure 	           6.10 E6    J/ha          1.0 E12      6209.30

**Notes:**
This table presents an evaluation of a freshwater marsh.  It presents emergy flows for different system categories – structure and function – for comparison, and calculates transformities for live biomass, peat and basin structure (lines 9, 10 and 12).  This particular evaluation presents some atypical methods for defining some of the unit emergy ratios used for converting energy flows (read the notes for line 4, run-in).  More often, unit emergy ratios are obtained from other studies for regions and processes similar to the one being evaluated.  
Many of the energy values in this evaluation are estimated using assumptions and estimates rather than established physical or chemical equations.  The notes for this table are an example of how to list assumptions used in an evaluation, however, it is usually preferable to include a more detailed description of your logic when using assumptions and circular reasoning to derive energy and emergy values.
One item stands out in this table and that is the total emergy value for basin structure (line 12).  It is an order of magnitude higher than any other listing in the table.  This does not necessarily mean that it is in error, but when you see a big difference in a single item, you should go back and check it to make sure there is no error.   In this case, without looking to see if the assumptions make sense or if there are errors in calculations, one reason for the number being so large might be that this represents a storage, not an annual flow as the column title suggests.  Where storages are being evaluated a new column title should be inserted or the units written out for those entries that are different from the title (eg. sej/ha for lines 9 – 12).

## Natural Systems

- Wetlands
- Forests
- Folio 3,
- Pg 53

**Table14**. Annual emergy supporting Southern Mixed Hardwood Forest Ecosystem (Florida) (Orrell, 1998)
- Note  Storage or Flow 		Raw Units       Emergy/unit       Solar Emergy
- 			   J/ha/yr 	      sej/unit 	         sej/ha*yr-1
*Sources*
- 1        Sun 			4.2 E13 	             1 	         4.2 E13
- 2        Wind 			2.5 E9 	      1,496 	         3.8 E12
- 3        Rain, physical 		2.2 E8 	    10,488 	         2.3 E12
- 4        Rain, chemical potential     	6.4 E10 	    18,199 	         1.2 E15
- 5        Run-in, chemical potential    	    0 	    48,459 	             0
- 6        Water use (Transpiration)       	2.6 E10 	    18,199 	        4.7 E14
*Storages (unit/ha)*
- 7 Biomass 			2.2 E12 	      5,504 	        1.2 E16
- 8 Soil moisture 		2.5 E8 	    41,000 	        1.0 E13
- 9 Phosphorus 		3.2 E7 	     4.0 E7 	        1.3 E15
- 10 Soil organic matter 		9.0 E12 	    11,360 	        1.0 E17
- 11 Tree species richness 		20 species 	1.1 E19 sej/spec.   2.2 E20
*Flows*
- 12 Net production 		3.1 E11       	     1,543 	        4.7 E14
- 13 Respiration 		4.7 E11 	     1,021 	        4.7 E14
- 14 Gross production 		7.8 E11 	        615 	        4.7 E14

**Notes:**
This table presents emergy values for a southern hardwood forest.  Similar evaluations have been completed for southern pine, northern spruce and other forest types.  If possible, when evaluating the forests for your region, choose a similar forest type.  However, the values for all these unmanaged forest systems are very close, and consequently using an average would not create a large error.  Later in the session we will look at a managed forest, and in these instances, there is a great deal of variability in emergy inputs, dependent upon the cultivation and harvesting methods used.  
In this table, the top six inputs are the only inputs to the system, and the transpired emergy is the value used to define the emergy needed to create all the other entities evaluated.  Lines 7 and 10 through 14 use some variation of this value to calculate unit emergy ratios for each of these entities.  The flows (lines 12 – 14) use the transpiration emergy divided by the annual flows to determine transformities.  Storages use some multiple of the transpiration to determine transformities.
The notes on this table are very thorough, but again, it is not clearly labeled in the table which unit emergy ratios that are determined from this study.  Also, the units for storage emergy do not have the same units as the column heading, but they are labeled over to the left at the sub-title.  Putting in additional column headings might avoid confusion.

## Natural Systems

- Wetlands
- Forests
- Lakes
- Folio 3
- Pg 77

**Table 22. **Empower of Lake Okeechobee (From Odum, 2000)
- Note   Item, units 	    Units/yr 	Emergy/unit 	     Empower 	      Emvalue#
- 			     sej/unit          E18 sej/yr      E6 Em$/yr
- Sources
- 1        Sun, J 		    1.22 E19 	             1 	          12.2                 12.2
- 2        Rain, g 	    2.29 E15           9 E4               206                  206
- 3        Tributary water, g 	    2.61 E15        5.6 E5             1484                1484
- 4        Tributary organ., J 	    1.74 E15      7.13 E5             1242                1242
- 5        Evaporation, g 	    2.64 E15      6.57 E5             1734                1734
- 6        Marsh product., J 	    7.28 E16 	        4026              293                  293
- 7        Water circulation, J 	      3.9 E10       1.84 E7                 0.7                   0.7
- 8        Open water emergy, sej/yr ——            1412            1412
- 9        Lake net prod, J 	    4.36 E16  	    3.21 E4           1412 	        1412
- 10      Phos. in streams, g 	    3.45 E8  	      7.2 E10             25 	            25
- 11      Phos., marsh cycle, g   3.29 E9  	      7.5 E10           247 	          247
- 12      Phos. sedim. cycle, g    9.67 E9 	    1.48 E11         1430 	        1430
- 13      Phos. plankt. cycle, g    6.06 E9 	    1.48 E11           900 	          900
- 14      Total lake empower 	          — — 	          	      2027 	        2027
- 15      Outflow, ag canals, g     0.44 E15       6.57 E5            289 	          289
- 16      Outflow reg. canals, g   2.07 E15  	     6.57 E5 	      1360 	        1360
- 17      Net org. sediment, J      4.62 E16  	     3.21 E4 	      1485 	        1485
- 18      Consumer. prod., J       1.09 E16  	     1.56 E5 	      1709 	        1709
- 19      Base fish prod, J 	    1.71 E14  	     1.00 E7 	      1709 	        1709
- 20      Game fish prod, J 	      8.5 E12          2.0 E8 	      1709 	        1709

**Notes:**
This table contains a great deal of extremely valuable information, but without clearer headings and more complete notes, some of the usefulness is weakened.  A few things are apparent however, if you check both table and notes carefully.  Use this table as a practice exercise to see if you can determine which entries are showing calculations of unit emergy ratios, and make a list of what entries were assumed to contribute to each of these items.  Also, what does it mean that the emdollar column is equal to the empower column?
Email me if you have questions: 
brandt-williams.sherry@epa.gov

## Processed Material

**Processed Material**

- Generic

- Sun
- Wind

- Fuel
- Electricity
- Materials
- Goods

- Water
- Resources

- Market

- Environmental
- Production

- Harvest &
- Finishing
- Production

- Services

- Materials

- Geology

- Fauna

**Notes:**
This is an example of a generic and aggregated diagram for the use of natural resources as feedstock for some economic process.  This diagram could represent the harvest  of managed timber and the conversion into lumber.  It could also represent the use of hydrocarbons, vegetable fibers and animal skins in the making of fabric and finished clothing.  The difference between the system presented here and the system shown at the beginning of the session is the human influence.  This diagram illustrates the economic interface present as humans begin to manage natural systems with the ultimate goal of converting resources into finished market goods. 
Try to write a verbal description of this diagram similar to the description provided in the third slide of this session.  Is there anything you think needs to be added?

## Processed Material

- Forest to wood products
- Folio 3
- Pg 16

**Table 5. **Emergy evaluation of boreal spruce (Picea aibes) and pine (Pinus silvestris) silvicultural production and timber extraction under 80 year rotation schedules in southern Sweden. (Doherty, 1995)
- 		     Resource 	        Solar 	      Solar emergy
- Note  Item 		     units/ha/yr 	       emergy 	             flow
- 		        (J,g,$) 	       per unit 	      E+12 sej/ha*yr-1
- I Environmental sources:
- 1.       Sunlight 		         2.57 E13 J                 1 	               25.7
- 2.       Wind, kinetic 	         8.73 E10 J           1500 	             130.9
- 3.       Evapotranspired rain                 1.95 E10 J          18200                    355.1
- F1 Silviculture:
- 4.       Motor fuel 	        5.59 E7 J 	        47900 	                 2.7
- 5.       Tractors, trucks                 	          66 g 	      6.70 E9 	                 0.4
- 6.       Human services                        18.70 $            1.50 E12                     28.1
- Y1      Above ground production       7.84 E10 J            ST1                        386.3
-                 (3.82 tons/ha/yr)
- F2 Harvesting:
- 7.       Motor fuel 	      5.97 E8 J             47900 	              28.6
- 8.       Feller, forwarder 	        188 g                6.70 E9 	                1.3
- 9.       Human services 	        101.26 $          1.50 E12                  151.9
- 10.     Capital investment 	         14.44 $           1.50 E12                    21.7
- Y2       Harvested biomass 	       5.85 E10 J           ST2                       589.7
- (2.85 tons/ha/yr)
- Summary of measurements:
- Solar Transformity:
- ST1    Above ground production                                 4928 sej/J
- ST2    Harvested biomass                                        10,083 sej/J

**Notes:**
This table presents an evaluation of harvested timber.  The notes are an excellent example of  providing complete and clear information about sources, assumptions and items included in all calculations.  It also illustrates the verbal presentation of notes mentioned in the third session.  It is clear from this table that two transformities are being determined (STn).
Note that while services have been reported in dollars, the equipment is presented in grams of material. 

## Processed Material

- Forest to wood products
- Compounds and elements to reagents
- Folio 4
- Pg 31

- Emergy Evaluation of Phosphorous Acid, 35% P2O5
- ________________________________________________
- Note	Item	Inputs	      Solar Emergy
- 				E12 sej
- ________________________________________________
- 1	Water	1.40 E8   J		     11
- 2	Phosphate rock	7.49 E5   g P	4,907
- 3	Electricity	1.89 E8   J		     51
- 4	Labor	1.05 E6   J		     43
- 5	H2SO4 (94%)	8.85 E5   g		   _136_
- 	     Total emergy**	****    ---**		5,149
- ________________________________________________
- 6	Total yield 		9.08 E5   g
- 	Total phosphorus in yield	3.96 E5   g P
- 7	Emergy per gram, P2O5	5.67 E9   sej/g
- 	Emergy per gram, phosphorus	1.30 E10 sej/g P
- ________________________________________________

**Notes:**
This is the first example of an evaluation where a complete listing of environmental services has not been included.  This evaluation represents an industrial production facility where the environmental services have already been concentrated into the feedstock, in this case water and phosphate rock.  While it is true that a certain amount of environmental resources enter the actual site of production in the way of sun, wind and rain, these inputs are not necessary for the production of acid.  Because the environmental services prior to processing have been incorporated into the unit emergy ratios for surface water and mined rock, we do not need to list anything in addition to this.  This would not be true in a facility depending upon solar energy for cooling, heating or photovoltaic energy resources or a process using rivers or rain for washing or cooling water.
This table presents calculated emergy per gram ratios for two different measures of the same product: the final product and a specific element in the product.  This particular study required different unit emergy ratios for different concentrations of the element phosphorus.  This extra step is not usually necessary unless you are developing some theoretical aspect of emergy evaluations; stopping at the most commonly used substance is acceptable, in this case P2O5.
While the calculated ratios are separate from the rest of the table, the fact that they are calculated from the study is not made clear in the table. An additional heading inserted above line 7 would avoid confusion about the intent of this evaluation.

## Processed Material

- Forest to wood products
- Compounds and elements to reagents
- Agriculture
- Folio 4
- Pg 23

- Table 16
- Annual Emergy Used to Produce Milk, per cow per year
- ___________________________________________________________
- 		Inputs	               Solar Emergy
- Note	Item	cow-1 yr-1	        E13 sej/cow/yr
- ____________________________________________________________
- 1	Sun	1.48 E14   J	3
- 2	Evapotranspiration	1.51 E11   J	418
- 3	Net topsoil loss	7.69 E9     J	95
- 4	Fuel	1.75 E10   J   	194
- 5	Electricity	5.02 E9     J	135
- 6	Potash	1.49 E5     g K	28
- 7	Lime	9.28 E5     g	156
- 8	Pesticides	2.33 E3     g	6
- 9	Phosphate	3.35 E4     g P	124
- 10	Nitrogen	5.07 E4     g N	205
- 11	Labor	1.28 E8     J	57
- 12	Services	2.19 E3     $	_1177_
- 13	Total emergy	---	2568
- ____________________________________________________________
- 14	Total yield, dry weight	7.63 E5     g
- 15	Total yield, energy	1.98 E10   J
- 16	Emergy per mass**	**3.37 E10   sej/g
- 17	Transformity**	**1.29 E6    sej/J
- 18	Empower density	1.90 E18  sej/ha/yr feed lot
- ____________________________________________________________

**Notes:**
Agricultural commodities are similar to harvested wood in that a natural resource – plants – are managed for maximizing monoculture growth then harvested for use as an economic product.  Again, the emergy evaluation is complete at line 13 and the separate section contains the energy yield information needed to calculate the by now familiar unit emergy ratios and an indice of value to planners and spatial modelers – the empower density.  We will talk more about this indice in a later session.
You may be confused to see fertilizers and pesticides listed in this milk evaluation, since cows do not directly use these inputs.  There are several ways this evaluation could have been completed.  This one includes the inputs to the grains used as feed for the cows.  This table could have been simplified by listing the three grains and using their respective unit emergy ratios from previous studies to determine the emergy used by the cow.  Either way, the overall emergy value would have been very similar, if not identical.  
This format was used for this study to keep the listings of inputs directly comparable to inputs for other agricultural commodities.  This allows ranking of each food for different inputs, and was important for evaluating different scenarios of limiting factors.  This demonstrates the utility of emergy evaluations to meet several different objectives – a big picture perspective, or a measure of internal components in a process.

## Summary

- Regional evaluations made up of a lot of smaller evaluations
- Most components are tangible and documented by reputable agencies

**Notes:**
Summary: Regional systems – states, nations, counties - are another example of a tangible system, with well defined boundaries, albeit arbitrary, and a great deal of information about trade, production and consumption.  We will talk more about this larger scale in the last sessions, but all a regional evaluation does is put all of these smaller scale evaluations presented in this session into a single synthesis.  These studies are not completed in order to calculate a unit emergy ratio, but every region has both natural systems, managed systems and processed material.  The same kind of data is collected and converted – its just the scale that has changed.