A discussion on energy savings, where hard-to-define words like ‘alternative energy’, ‘green’, ‘sustainable’, ‘environmentally conscious’, and ‘premium efficiency’ are used, can often be far from cost savings. A true energy audit that seeks to eliminate energy waste from an operation’s process will begin with the more mundane task of defining the existing energy consumption parameters. Considering ‘high tech’ or leading edge solutions should be relegated to the end of the energy saver’s task list.
The Race To Flight
An analogy can be made from the race to first flight. Many people know that the Wright brothers are credited with the first heavier-than-air controlled flight. What many do not know is that there were several well-funded scientists also attempting to prove that heavier-than-air flight was possible. Alexander Graham Bell was one. Samuel Pierpont Langley, Secretary of the Smithsonian Institution, was another. The focus of flight research and engineering was the belief that a lighter, more powerful, and more efficient engine was the missing link to successful powered flight. Langley even developed “Langley’s Law” – an equation to predict the amount of power required to sustain flight. Using some elegant mathematics, this law was promptly discredited by another leading scientist of the day, Lord Kelvin. However, Langley had the funding of the US military and the resources of the Smithsonian behind him. After some success with small scale model’s, Langley’s well publicized $50,000 ‘aerodrome’ flew “like a handful of mortar” into the Potomac, abruptly ending his funding.
With comparably very little funding, brothers Wilbur and Orville Wright decided to focus their efforts on aerodynamics – lift, stability, and control. They built their own wind tunnel in their bicycle shop for testing airfoils and propellers. So intent was their focus that they built and flew their prototypes achieving controlled flight before even beginning work on an engine. Once they were satisfied that they could control a ‘flying machine’, they built an engine (in about 6 weeks) and mounted it to their plane. The resulting flight on December 17, 1903, is heralded as the “first controlled, powered and sustained heavier-than-air human flight” aka, the invention of the airplane. Essentially, they proved that when building an airplane, the wings are more important than the engine.
What does this have to do with hatcheries and energy savings?
The point is that energy savings is not really about getting the latest equipment labeled ‘high-efficiency’. What matters more is the proper design, installation, and operation of the systems that the equipment is a part of. Generally speaking, replacing old equipment with new ‘high efficiency’ equipment will result in a 5-25% energy savings for that system (assuming the old equipment was the right equipment for the job, and that it was installed and operated correctly). It is this assumption that this article is going to highlight.
How is it possible, one might ask, to determine if equipment is designed, installed, or operated correctly? That is generally not part of an aquaculture degree or diploma curriculum. It can be generally assumed that is some piece of equipment is prone to failure, there is an issue with the design, installation, and/or operation of the equipment.
Look, Touch, Listen, and Smell
There are some simple ways that anyone can learn to see, feel, or hear the hints that there is an issue with some equipment. Consider pumps for example. Pumps are not intended to deafen those who pass by. Nor were they intended to operate hot enough to cook your breakfast. Nor are they designed to vibrate loose from their bases. And most obvious of all, they are not intended to frequently breakdown. To extrapolate to blowers and chillers: a blower is an air pump, while a chiller compressor is a refrigerant pump. The same principles apply with the added note that chillers should not have suction lines covered with ice and frost unless they are cooling below 3°C.
After walking through a facility’s mechanical room each day for a month, most people will be able to instantly detect a change in the room when entering. Learn to listen and search out the source of any new sound, or smell.
Only use touch when it is certain that it is safe to do so. Beware of touching equipment that may start or stop automatically (some drum filters) or that draw electricity unless you have been assured by authorized personnel that it is safe to do so (ie the power has been disconnected).
Once you have isolated the problem equipment and mitigated any immediate risk to stock, personnel, and the facility, consider the energy consumption connected to the equipment in question and the portion of the process it is achieving.
Measure and Record
Because aquaculture operations are often 24/7/365, it is important to have measurement points throughout the systems. These can be as simple as temperature gauges, pressure gauges, clear pipe for visually confirming flow, visible flow into a tank or a drain, flow meters, level markers etc. Once these points are established, daily check lists will provide quick confirmation of whether the current status is normal, part of a trend toward failure (filters becoming fouled causing lower water flow perhaps), or a case of human error (valve not seated all the way resulting in extra water demand perhaps). Equipment failure is generally a sign of one of two things – human error or inappropriate application for said piece of equipment (aka human error). The latter error (inappropriate application) will make even the most energy efficient machine operate inefficiently – and then fail.
The take home point is that measuring and recording system status will both predict (and thus hopefully prevent) failure and illuminate inefficiencies. An inefficiently operated system is prone to failure. Inefficiently operated equipment is likewise prone to failure.
Taking Measurement to the Next Level – Is it Efficient?
Another perspective on measurement is that it can be used to calculate efficiency of equipment. This can be mathematically challenging simply to gather the proper data and convert measurements into consistent units prior to applying any formulae. For almost every calculation imaginable there are now ‘online calculators’ available. Simply use Google to search for “pump horsepower calculator”, for example. Several links are available where one simply enters the measured data (flow and pressure), perhaps also some constants such as gravity (again use Google if needed), and presses ‘Calculate Now’ to view the required horsepower. If such a calculation indicated 3hp was required, and your process was using a 10hp motor, you likely have found inefficiency in your system.
Research the Equipment
Every piece of equipment should have a company and/or brand name, model #, and nominal ratings on its nameplate. And in 2012, almost every company has a website listing all specifications for their equipment. Other literature such as a manual, an installation guide, a bulletin, or proper selection information, is often available for download or viewing. Given enough motivation (aka high energy costs) one can often find the information needed to determine how efficient equipment may be, or whether the equipment was intended for the operating conditions being imposed on it.
Common Low-Cost Efficiency “Upgrades”
First, deal with obvious waste. Aquaculture systems design and equipment selection is often based on feeding rates and/or biomass. However, the temptation that operators often face is basing their system flow rates on equipment capacity rather than biomass because the water quality may be better. This may or may not be helpful to fish, but it is certainly not conducive to energy savings.
If you heat water, first consider insulation of pipes and rooms/building containing temperature controlled water. Then consider heat recovery. If you have heat recovery but some water is not being returned to the heat exchanger, you have a significant energy savings opportunity. One planned tank farm expansion recently decided to pursue heat recovery when it was demonstrated that 3x more tanks could be temperature controlled with the same amount of heating equipment and energy consumption as would be possible without the heat recovery addition.
If you heat with oil, have an expert clean, test, and adjust your boiler to maximize efficiency. Boiler efficiency can degrade by as much as 50% by excessive or inadequate air entry into the combustion chamber. Fouling of the heat exchanger inside a boiler can also affect efficiency by as 10% per year (with residential use).
Pumps generally have a specific range of operating points where they are 60-80% efficient. A 20% change in flow or pressure may reduce efficiency by 30-50%. Pumps are vulnerable to operation outside of their design parameters and may fail simply due to being restricted too much for too long. If you regulate pumps by restricting valves permanently, buy a smaller pump. Or if you need the extra capacity occasionally, use two smaller pumps instead of a single large one that normally runs restricted. Or install a VFD to slow down your pump. A VFD also may extend the lifetime of the pump significantly – less speed equals less friction and less rotations, which both equal less wear.
A cheap fix that is often overlooked on efficiency upgrades is to re-program or upgrade controllers. Switch out controllers accurate to one degree for a controller accurate to a tenth of a degree. (This saved one hatchery thousands of liters of oil each year for the cost of running a wire 30 feet). In some cases, re-program or replace on/off control with proportional control. This may require expertise relating to the equipment being controlled. A control valve for example that is used to control temperature might mix flows of two different temperatures to achieve the target temperature. A proportional valve and controller would ensure that exactly the proper amount of water and heat is added (or removed when cooling). However, chillers have minimum flow rates that must be adhered to. The programmer would need to be aware of this flow rate and ensure the controller does not restrict the flow below acceptable levels and freeze up the chiller.
For Energy Savings: Equipment Management is a Higher Priority than Efficiency Ratings
The Wright Brothers demonstrated the priority of aerodynamics over engine power when discovering flight. Analogously, to discover energy savings at a hatchery, how the hatchery and its equipment is operated is a higher priority than replacing its equipment with ‘high efficiency’ alternatives.
If energy savings is something your hatchery is concerned with, audit your current energy uses first. Examine design, installation, and operations of any frequently failing equipment. Only after current energy use has been well-defined system-by-system, consider replacing equipment and/or processes and/or practices for the sole purpose of energy savings.