Emergy of Alternative Investment
A particular development might be compared with the intensity of development that is predicted assuming the same feedback investment F had been matched with input of environmental resources according to the regional investment ratio (IR). In Figure 9.3, emergy flow P3 is the sum of the emergy of F and the environmental emergy flow I3 (equal to F/IR).
Emergy of Potential Matching
A development should also be compared with the economic matching that could result if all the original environmental emergy flow I1 was retained and matched with feedback emergy according to the regional investment ratio IR. In Figure 9.3, this alternative emergy flow P4 is the sum of the original environmental emergy flow I1 plus the feedback from the larger economy
For example, one of the summary diagrams from our study of development alternatives for the Mississippi River (Odum et al., 1987c) is Figure 9.4 with details in Table 9.2. The development that took place with channelization, levees, shipping, floodplain agriculture, and so forth (Figure 9.4b) increased the total emergy flow from 46 billion to 76.2 billion Em$/yr, but it diminished the environmental emergy from 46 billion to 15.7 billion Em$. Empower was increased.
This development may be compared with the alternative that matches the investment of 60.5 million Em$ with environment according to the investment ratio (IR = 7): (60.5 + 60.5/7 = 69.1 X 109 Em$/yr). The observed development is close to that which is economical according to the regional matching principle.
Figure 9.4c shows the potential (368 billion Em$/yr) if development could be revised to restore the original environmental contributions while also combining these with compatible economic development attracted according to the emergy investment ratio (IR = 7). This comparison shows that the economic vitality of the Mississippi system might be increased six fold by a more holistic pattern of development.
The evaluation in Figure 9.4 omits the very large emergy flows of sediment erosion, now being diverted to the Gulf of Mexico but which formerly enriched the lowlands and expanded the Louisiana marshes. Inclusion of the sediments would increase the estimate for long-run economic benefit by many times (Odum et al., 1987c).
Figure 9.4. Emergy flows for alternative development of the Mississippi River basin (Odum et al., 1987c). (a) Before development, (b) Developed basin, (c)Potential development.
Solar
Empower
|
Em$/yr#
|
|
Item*
|
(x1022 sej/yr)
|
(x109 1993$)
|
Original
River:
|
||
Chemical
potential of fresh water
|
11.5
|
81.5
|
Geopotential
of river
|
10.0
|
70.9
|
Water
used by the original floodplain
|
7.9
|
56.0
|
Modified
river in 1986
|
||
Water
used by developed and drained
|
3.0
|
21.2
|
floodplain
|
||
Sediments
carried
|
230.
|
1631.
|
Sediments
discharged to Gulf of Mexico
|
127.
|
900.
|
Fisheries
production
|
0.99
|
7.0
|
Loss
of coastal land
|
1.4
|
9.9
|
River
energy used by barges1
|
0.43
|
3
|
Purchased
inputs for economic use
|
||
In
agriculture, forestry, and crayfish culture
|
0.86
|
6.1
|
In
river transportation2
|
0.96
|
6.8
|
(If
railroad substituted for river transport)
|
(4.61)
|
(32.7)
|
In
oil and gas production
|
5.2
|
36.8
|
In
urban economy
|
8.2
|
58.2
|
Oil
and gas production for use elsewhere
|
55.2
|
391.5
|
* Some items are included within others.
# Solar empower in column 2 divided by 1.41 X 1012 sej/1993 U.S. em$.
1 If fraction of river required per vessel considering turbulent eddies is 100 times vessel displacement.
2 Includes fuel use, shipping goods and services, and operation of locks. Source: Condensed from Diamond (1984) and H. T. Odum et al. (1987c); update and elaboration of earlier studies by Young et al. (1974); Bayley et al. (1977); and Zucchetto et al. (1980).