February 15-18, 2009 Washington State Convention Center Seattle ...

ENERGY USE, RESOURCE CONSUMPTION, AND SUSTAINABILITY OF AQUACULTURE
SYSTEMS – AN INTRODUCTION
John Colt
National Oceanic and Atmospheric Administration
Northwest Fisheries Science Center
2725 Montlake Blvd. East
Seattle, WA 98112 USA
john.colt@noaa.gov
Sustainable development implies that current demands will not compromise the ability of future generations to meet their own
needs and that food production systems should be as efficient as possible and minimize environmental impacts. Different production
systems will have different labor, energy, and physical components. To compare these systems from a sustainability
perspective, it is necessary to be able to evaluate the components of each system in terms of some type of “common currency.”
The four commonest types of sustainability analysis are:
Net Energy Analysis. Energy analysis (or net energy analysis) is a form of energy accounting that considers both direct and
indirect energy inputs to a given process. The major aquaculture inputs are material inputs (feed, pure oxygen, calcium carbonate),
energy inputs (electrical, gasoline/diesel, and natural gas), labor, and gametes. Fixed capital components such as concrete,
steel, aluminum, fiberglass, and plastics in the facility are considered. Each input or output may have three types of energy:
direct energy, indirect energy, and transportation energy. Direct energy is the amount of heat (∆H) that is released if the compound
is burned in a bomb calorimeter. Indirect energy is the amount of energy that was needed to produce a unit weight of a
given compound. The transportation energy is the energy required to transport material to and from the facility. Energy analysis
is based on estimation of energy density (MJ/kg) and the mass of the compound used.
Greenhouse Gas Emissions. Greenhouse gas emissions (carbon dioxide, methane, nitrous oxides, and fluorocarbon) are of
current interest because their potential impact on global warming and ocean acidification. Greenhouse gas emissions are based
an emission factors (kg/kg) and the mass of the compound consumed.
Life Cycle Analysis. Life cycle assessment is a “cradle-to-grave” approach for assessing industrial systems. The impacts are
classified into global (climate change, ocean acidification, ozone depletion, resource depletion), regional (photochemical smog,
acidification), and local (human health, terrestrial toxicity, aquatic toxicity, eutrophication, land use, water use). Because LCA
considers all three media (air, land, and water), it helps to prevent shifting environmental problems from one media to another,
or from one impact category to another. LCA methodology has been standardized by the International Standards Organization
(ISO) 14000 series. The amount of information needed to conduct an LCA is immense and typically requires the purchase of
commercially available LCA software packages.
Ecological Footprint Analysis. Ecological footprint analysis estimates the surface areas of the ocean and land needed to support
a given facility. This included area to produce the feed and process the wastes generated by the facility. Small ecological
footprints are assumed better than large footprints and are typically expressed in terms of the area of the aquaculture facility
(i.e., ha of ocean per ha of facility).