Abstract:
The development of the energy crisis has caused the
use of depletable energy resources to be monitored quite
closely in the United States. Within the agricultural
sector, irrigation is a large user of energy, with the
potential of using many times more energy than all other
agricultural field operations. A better understanding of
how energy is used by different irrigation systems could
facilitate more efficient use of energy by one of the
largest energy consumers in agriculture.
This thesis attempts to realistically evaluate the
total amount of non-renewable energy resources consumed in
the irrigation process. Five portable and permanent
sprinkler system types, plus trickle and gravity irrigation
systems were studied. An evaluation of the energy required
to manufacture the equipment, install it in the
field, operate it, and transport it for an entire irrigation season was made. This evaluation was carried out in
a variety of operating situations, with varying acreages,
consumptive use rates, and total irrigation requirements.
The paper begins by giving some background information
about agriculture and irrigation as consumers of energy. A
review of some of the research previously done which relates
to energy use in irrigation is given.
The evaluation of energy use by irrigation systems presented
in this thesis were made with the use of a simulation
model which was developed on the Oregon State University OS-3
Computer System. The model predicts energy requirements of
an irrigation system by evaluating pumping energy requirements
with basic hydraulic equations, the manufacturing
energy requirements by calculating the required amounts of
basic materials making up the system and the energy of
manufacture of those basic materials. The energy for installation
and the energy for transportation were evaluated
by simulating methods of operation and management used in
Oregon.
The input parameters used in the modeling process.
reproduce as closely as possible operating conditions encountered
in Oregon. System types, component depreciation
life, irrigation efficiencies and the range of irrigation
requirements are ones that could typically be found in
Oregon.
For the situations considered, it was concluded that
gravity irrigation required much less energy than other
system types. The energy requirement for drip systems
was about midway between the energy requirement for gravity
systems and for sprinkler systems for most cases considered.
The relative order of energy requirements for the various
sprinkler systems was dependent upon the operating conditions
considered.
