Research Article

Energy-Based Evaluations on Eucalyptus Biomass Production

Table 2

Emergy evaluation of eucalyptus plantation (7-year cycle); yields are for pulpwood only.

NoteItemQuantityUnitUEVSolar emergy flow
unit ha−1sej unit−1Per rotation
E12 sej ha−1
Per year
E12 sej ha−1 yr−1

Environmental inputs
 1Actual evapotranspiration3,85E11J30,57611,775.501,682.21
 2Topsoil loss70E03g7.18E0850.007.14
Purchased loss
 3Diesel oil529.20*L 2,063.80294.84
 4Machinery17,700g 119.0017.00
 4Labor J 1,362.26194.61
 6Fertilizer (06-30-10) g 1,202.95171.85
 6Fertilizer (14-00-15) g 578.3482.62
 7Formicide1,000g 24.863.55
 8KCl g1,50E09229.2832.75
 3Lubrificant oil22.80L 87.7812.54
 7Scout7.60L 188.9727.00
 9Propagules1,845Unit 295.0042.20
 10Water5.56L 7.001,00
 11Lime g 1,680.00240,00
Transport lime to site 100.00 t km−1 24.003.43

Total inputs2,812.74

Outputs
 12Harvested pulpwood290.50m3ST119,457.442,779.63
 13Harvested pulpwood2.16E12§JST219,457.442,779.63
ST1UEV harvested biomass (volume) sej m−3
sej m−3 yr-1
ST2UEV harvested biomass (energy) sej J−1
sej J−1 yr−1

Assuming use of wood as biomass for pulp and cellulose mills.
§Assuming use of pulpwood as biomass for energy; these data do not include energy in nonpulp products (bark and limbs), which might be used when energy is the principal output.
UEV for evapotranspiration = 3.10E4 sej J−1 [22], evapotranspiration = (7,796 mm ha−1) * (1.00E4 L mm−1 ha) * (1 kg L−1) * (4.94E3 J kg−1).
Topsoil loss based on the organic matter content = (5.4E4 kcal kg−1 OM) * (1,28% OM)* (4.17E3 J Kcal−1) * (2.4E5 sej J−1 [23]) = 7.18E11 sej kg−1.
Diesel UEV and emergy content [6] = (1.32E8 J galão−1) * (1 gallon 3.8 L−1) * (1.1E5 sej J−1) = 3.85E7 sej L−1.
(4) UEV for machinery depreciation = (6.7E9 sej g−1), [22] after [24], Per kg = (6.7E9 sej g−1) * (1,000 g kg−1) = 6.70E12 sej kg−1.
(5) UEV for labor 4.5E6 sej J−1, by [25], energy of human labor = (231.8 h) * (2500 kcal dia−1) * (day 8 h−1) * (4,186 J kcal−1) = 3.03E8 J.
(6) UEVs: K2O = 2.92E9 sej g−1 K [6] * 83%K K2O−1, P2O5 = 2.99E10 sej g−1 P [6] * 43,7% P , N = 7,7E9 sej g−1 N [6], 06-30-10 has 6% N, 30% P2O5 and 10% K2O; and 14-00-15 has 14% N and 15% K2O.
(7) Based on the UEV of pesticides 2.49E10 sej g−1 * 1000 g kg−1 [25].
(8) UEV: K2O = 2.92E9 sej g−1 K [6] * 1,000 g kg−1, KCl * 63% K2O KCl−1 * 83% K-K2O−1.
(9) UEV of a seedling is 1.6E11 sej, from [9].
(10) Water potential chemical energy (4,94E3 J kg−1) multiply by irrigation UEV (4,28E5 sej J−1, [24] = 1.26E9 sej kg−1 or 1.26E9 sej L−1 H2O.
(11) Lime UEV (1.68E10 sej g−1) [6].
(12) Yield = (41.5 m3 ha−1 ano−1) * (7 years) = 290.5 m3 ha−1.
(13) Wood energy content = (290.5 m3 ha−1) * (495 kg m−3) * (1.5E7 J kg−1) = 2.16E12 J ha−1, energy content [26] from [27].
*[9] considered the purchased loss of diesel oil as 783.50 L ha−1 because it was accounted for to support two trucks for repair and fuel used together for two harvester and forwarders.