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Energy inputs in production agriculture: Life cycle analysis

Energy inputs in production agriculture: Life cycle analysis. Fuel (for tractors, powered implements, running irrigation etc.) Fertiliser Agrochemicals (sprays mostly) Farm buildings (energy and carbon invested in constructing them) Farm vehicles and machinery

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Energy inputs in production agriculture: Life cycle analysis

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  1. Energy inputs in production agriculture: Life cycle analysis • Fuel • (for tractors, powered implements, running irrigation etc.) • Fertiliser • Agrochemicals • (sprays mostly) • Farm buildings • (energy and carbon invested in constructing them) • Farm vehicles and machinery • (energy and carbon invested in manufacturing them) • Irrigation • (energy and carbon invested in infrastructure)

  2. Sample crop: Apples • Some crops are annual. • Conduct an annual life cycle analysis • Some crops are perennial. • Take a longer term analysis

  3. Fuel use: Orchard case study • Orchard tractor uses 10l diesel fuel per hour. • In one season it operates for 45 hours for each ha it works on. • This is equivalent to 450 litres per ha per year. • At primary content of 42 MJ/litre of diesel this is 18900 MJ per ha per year. • This is equivalent to about 1050 kg CO2 per ha per year emissions.

  4. Fertiliser use: Orchard Case Study • Fertilisers, especially nitrogen, are very energy intensive to produce. • An annual application of 50kg per ha N, 10kg per ha P, and 40kg per ha K would represent: • 3800MJ/ha • 200 kg CO2 per ha

  5. Agrochemical use: Orchard case study • Fungicides • 25kg a.i./ha/yr. • Embodied energy 210MJ/kg a.i. • Insecticides • 1kg a.i./ha/yr. • Embodied energy 310MJ/kg a.i. • Herbicides • 5kg a.i./ha/yr. • Embodied energy 310MJ/kg a.i. • Total energy = • (25x210)+(1x310)+(5x310) = 3963MJ/ha • Total kg CO2 = • 3963x0.06 = 238kg/ha

  6. Farm buildings: Orchard Case Study • For basic orchard production: • 5m2 building per ha of orchard • Machinery shed • Storage of empty fruit bins • Assumed to be a galvanised steel barn • 590MJ/m2 in construction • Assumed to need replacement after 20 years • Embodied energy: • 590x5/20 = 147.5 MJ/ha • CO2 emitted: • 147.5 x 0.1 = 14.75kg/ha

  7. Machinery & equipment: Orchard Case Study • Tractor • 1 tractor per 10 ha; typical weight 3500kg, depreciated over 15 years • = 23kg mass/ha/yr. • Energy embodied in tractor: • 23 x 66 = 1518MJ/ha/yr. • CO2 @ .095kg per MJ • = 144.21kg/ha/yr

  8. Machinery & equipment: Orchard Case Study • Other machinery • Sprayer, mower, mulcher, fertiliser spreader, forklift etc. • Total weight 5300kg (for 10 ha, over 15 years) • Energy embodied in machinery: • 35.3 x 51.2 = 1809MJ/ha/yr. • CO2 @ .1 kg per MJ • = 180.9kg/ha/yr

  9. Total energy and CO2: Orchard Case Study

  10. Completing the life cycle: Orchard Case Study (conv.) • Energy embodied in fruit eaten • 2.5MJ per kg • Carbon • Sequesterisation into orchard soil: 2000kg carbon/ha/yr. • In woody plant tissue: 500kg carbon/ha/yr. • Also in fruit, approx 400-1000kg carbon/ha/yr. • CO2 equivalent • 2500 /12*44 = ~ 9200 kg/ha/yr. • Five times more CO2 taken from air than released in a single growing cycle.

  11. Life cycle beyond the orchard: • Cold storage: • Average storage period = 6 months. • 1-2MJ/kg (operating) • Transport: • By ship from New Zealand • 2MJ/kg • By road from Italy to Ireland • 2MJ/kg • Packaging: • O.5kg cardboard per kg fruit • @8MJ/kg cardboard = 4MJ

  12. Life cycle beyond the orchard: • Transport from shop to home: • A car using 10l/100km uses about 1kW power per km travelled • A 3 mile trip to the shop and back (6 miles or 10km total): • 10kW • Assume you collect 10kg of groceries, 1kg of which is a bag of apples • Then 1 kg of apples required 1kW to collect. • Equivalent to 3.6MJ per kg collected • Question: • What about if you drive 6 miles to town for a take-away Pizza? • Goodfellas 400g ~ 4MJ • Remember 1 watt hour = 3600 joules

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