There is a huge potential for energy saving in the life support systems (LSS). For comparison, in industrial systems the potential savings range between 30% and 40%. In the aquarium world, dealing with a delicate organic process in which parameters can change, good results should also be expected. A large amount of the energy is consumed by pumps. Therefore a first logical step for energy saving lies in determining the pumps duty point(s). Pumps are the backbone of the aquarium, creating the needed water movement in the exhibits and feeding the LSS. The pumps’ delivery head must be enough to over-come all resistance losses caused by pipe work, appendages, protein skimmer, sand filters and so on. During pump selection safety margins are added in ensure that flow required in the design is realised. Nowadays, for getting flexibility in pump performance and to avoid throttling of the system, the use of variable frequency drive (VFD) is widely used. However, the use of VFD can have unexpected effects on the LSS system. When pumps deviates more to the right of their Best Efficiency Point (BEP), the grade of efficiency can decrease and Net Positive Suction Head (NPSH) will diminish, giving way to higher risks of vibration (including cavitation) and noise. Then, mechanical pump load will increase, speeding up the maintenance frequency, causing more down time of the LSS which will have an impact on the controllability of the LSS. In addition, pipe work and its components will face more mechanical impact, increasing the risk of cracking pipes, giving way to failures like super-saturation.
There are a number of factors to consider when planning a new aquarium facility. One of the most important factors to consider is how will aquarium seawater will be supplied? Most inland facilities are obligated to make their own saltwater, but facilities located adjacent to natural seawater sources must evaluate collecting a continuous source of water. A source of good quality natural seawater can have a long term impact on operational cost as well as provide benefits to animal health. Important aspects to consider in the planning for a seawater intake for an aquarium facility are as follows: Where will the intake be located? The geographical location of the intake impacts the overall water quality that the intake will deliver. Things to consider include land based activities or industries, maritime traffic and freshwater intrusion sources such as natural stream beds or high capacity storm drains. Local and seasonal currents as well as tidal swings will also have an impact on the seawater intake location. What type of intake would be appropriate for the facility? There are number of different ways to intake seawater for use at an aquarium facility. This includes sea floor pipelines, pier based pump stations, land based pump stations, seawater wells and rainy collectors. Different methods and examples of facilities using similar methods will be discussed. Logistics, capital costs and long term operational costs all play a role in the method selected. What is the water quality of the source water? Is it suitable for use in the Aquarium facility? The seawater quality for any intake will vary by season and by day depending on a number of different things. Seasonal water quality samples can help the decision making process in regard to suitability and the treatment regime required. Water bodies that are high in pollutants may not be acceptable for use in the aquarium, forcing a seaside facility to manufacture seawater or obtain good quality seawater in other ways such as by truck or barge. Regulatory requirements will impact both the seawater intake and the discharge facilities. Local regulatory agency requirements vary from location to location and fall under the umbrella of national regulations as well. Discharge regulations focus on water quality parameters such as concentrations of oxidants, suspended solids, BOD and bacteria counts. At times discharge water quality parameters are lower than the water quality that you may see at the seawater intake itself. Chloride limits by local sewer agencies can also come into play in facility planning.
During a recent renovation, the Vancouver Aquarium Marine Science Center (VAMSC) installed a District Energy System or DES for short. VAMSC is one of only a few institutions in British Columbia to integrate such an innovative system to manage energy use. VAMSC follows LEED and ISO 14001 construction practices and in 2015 was awarded the Green Award by AZA in part due to the implementation of the District Energy System. The DES is a site wide low grade energy loop that extracts or rejects energy through a variety of sources. Heat producing equipment such as chillers and food service refrigeration reject heat in to the loop through liquid cooled condensers. Isolated water and glycol systems are circulated using variable speed pumps to move energy around the system. Heat is extracted through heat exchangers to warm habitats, galleries and coils in local HVAC air handlers. Cooling is accomplished in the same way using the cold side of the system. Temperatures in the loop are maintained in a specified range using seawater heat exchangers, boilers, heat pumps and a cooling tower. Planning is underway to install a geothermal field to store excess heat produced in warmer months for use in the winter. The net effect is that heating and cooling costs can be reduced since it requires much less energy to redistribute the energy than it would to produce it at multiple points of use.
Life support system instrumentation indicates equipment function, but it is water quality parameters that indicate equipment efficacy and resource allocation that indicates equipment efficiency. Equipment parameters—pressure, flow, water level, etc.—can be operating within “design specifications”, yet water quality parameters (e.g., nutrients, alkalinity, pH) can be unsuitable for aquatic life and/or excess resources (e.g., water, energy, labor) must be expended to normalize the environment. In the past, available technologies were not able to address the demands of a healthy closed aquarium habitat without eventual recourse to substantial water exchanges to normalize the environment. This situation no longer prevails. Dissolved contaminants can now be physically removed from solution by ozone-assisted foam fractionation, a widely accepted industry standard in the modern era. Nitrite accumulation can be managed with recently-developed and user-friendly denitrification technologies. Phosphates can be controlled with modern water treatment tools and pH decline can be addressed via well-designed gas exchangers to ameliorate CO2 accumulation from animal and bacterial respiration, and the degradation of wastes and uneaten food. Given these relatively recent advances, it is clear that water quality challenges in a modern aquarium have their root causes tied to incomplete life support system design and/or inappropriate system operation. By ensuring that life support systems are well designed and operated appropriately, optimal water quality can result and excess resource expenditure can be avoided, consistent with the conservation and fiscal priorities for the modern zoo and aquarium.
Pressured by the rapid pace of climate change and ocean acidification, aquariums are feeling an increased urgency to provide a message of conservation and sustainability to their visitors. Research shows that people are more receptive to this message when presented with concrete evidence of how their actions can create positive change. As such, aquariums have a stronger incentive than ever to lead by example, reducing their demands for energy and freshwater. Traditional aquarium life support systems have been very energy and freshwater use intensive, primarily due to pump energy, heating and cooling demands and use of water for backwashing of filters. Such systems can easily account for more than 50% of the energy and water use of a facility. But opportunities to reduce energy and water use with such systems are minimal without unacceptable reductions in water quality. However, innovative system design alternatives are being included in new aquariums and renovations. These incorporate drum filtration, which can drastically reduce energy and water use over traditional pressurized filtration systems. Additional strategies, such as integration of life support heating and cooling into energy efficient building mechanical systems introduce the potential for further energy reductions. Such systems are most effective when system elements are arranged so that gravity flow replaces a significant amount of pumping. While capital costs of such systems may be somewhat higher than traditional systems, life cycle cost analysis can be used to demonstrate that substantial energy and water savings and reduced equipment maintenance and replacement costs can easily offset the initial cost premium of such a system. By pushing the design of our future facilities, aquariums can lead by example as they strive to increase the impact of conservation education on their visitors.