Agriculture Reference
In-Depth Information
the emergy use could be substantially reduced by using only ground water.
Producing the woodchips, which accounts for 10% of the total emergy
used, within the geographical boundaries of the farm would improve re-
newability. Currently they are residuals supplied from a local gardener
who prunes and trims local gardens. In a larger perspective, there are, thus,
few environmental benefi ts from becoming self-suffi cient with wood chips
in the case system. According to the LCA analysis, the composting process
accounts for 30% of greenhouse gas emissions, and using less wood chip
compost would reduce the overall global warming potential.
Electricity, which is primarily used for heating and lighting in the pro-
duction of seedlings, constitutes 11% of the emergy used. It is no doubt
convenient to use electricity for heating, but substituting the electricity
with a fi rewood based system would largely reduce the emergy. Alterna-
tively, it may be worthwhile to consider harvesting excess heat from the
composting process to heat the green house.
As for the distribution phase, the case has the potential for decimat-
ing fossil fuel consumption by replacing the current customers with some
of the many households located within few kilometers of the farm. This
could dramatically reduce the 70 km round trip each week. The current
way of organizing the distribution, however, is extremely effi cient when
compared to the alternative where customers would go by car each week
and pick up the produce. The latter solution would require up to 1,000,000
car-km per year based on the case farmer's calculation. With a fuel effi -
ciency of 15 km/L this translates to 66,666 liter of fuel. This is almost 40
times the fuel consumption for the model system (1737 L).
1.6.3 OUTLOOK FOR EMERGY USE FOR L&S
In a foreseeable future with increasing constraints on the non-renewable
resources [6,60], which currently are powering the society with very high
EYR-values [23], it is desirable or even necessary that agricultural sys-
tems become net-emergy providers, i.e., that more emergy is returned to
society from local renewable resources than the society has invested in
the production [61]. This requirement means that the contribution from
R has to be bigger than F. Bearing in mind that R cannot be increased as
