By Sterling D. Allan and Paul Noel
Pure Energy Systems News – Exclusive
Copyright © 2005
Tankless Water Heaters are Brutal on the Grid When Popularized
Tankless water heaters draw energy on demand, and do not have a thermal energy storage facet. Multiplied by many customers’ hot-water usage patterns, these surges of energy amount to a significantly higher peak load for utilities, resulting in increased costs and, more significantly, in increased waste during non-peak times.
While tankless water heaters do indeed usually provide a customer with substantial out-of-pocket savings on their fuel bill, a problem arises when a lot of people use such a system. It puts a heavy load on the grid during peak times.
Individual customer savings may be high, but a lot of customers using the system results in increased costs for the grid due to a net increase in energy generation required due to the increased peak load spikes.
Tank vs. Tankless from the Grid’s Point of View
Compared to the tankless systems, tank-based water heaters are energy hogs because they have to maintain that tank of water at a high temperature during long periods when no water is needed. Though insulated, there is still a constant loss of heat energy into the environment.
The most obvious waste is during those times when a family might be away on vacation. But even the spans at night while the family is resting, or during the day while they are away from home, the water heater churns away, keeping that tank of water hot.
“On-demand”, tankless systems, on the other hand, heat the water from cold to hot as it is needed, and then shut themselves off. There is no interim period of waste of heat into the surroundings, other than the water between the heater and the fixtures.
So yes, you can see why the “on-demand”, tankless water heater system would save as much as 60% over the tank-based water heater when compared side by side.
But now think of this in terms of the electrical grid, and you will see that the collective use scenario creates a problem.
The water tank system, though inefficient for the consumer, serves as an energy storage system as far as the grid is concerned. It buffers the energy consumption away from peak energy load times. Peak usage is still the same, but the energy required to heat the water is spread out over a much wider period of time. The tank of hot water serves as thermal mass storage unit. It is already hot when you jump in the shower in the evening, and then tops off as you shower and after you get out, for example.
Tankless systems, on the other hand, draw a large spike of power demand during times of use. The overall usage may be 60% less, but the spikes are much higher. The tankless system has to heat that water from cold up to hot during the time that you are showering, for example, not before or after.
Multiply that by many thousands of people in a municipality, and you create a real problem for the electrical generating utilities.
Utilities Have to Match Peak Requirement & Vent During Non-Peak
Utilities have to build and maintain their systems to handle peak load — that time when people tend to use the most energy, such as at night as people return home, turn on their lights, cook dinner, run their washers and dryers, turn on their televisions, vacuum the floor.
The utility needs to have enough electricity ready to go so that when you turn on your switch, the electricity flows immediately. Collectively, that means that the higher the peak load, the larger they have to build their plants to handle those peaks.
In Florida, where tankless water heaters have been around for about 20 years, and have become quite popular, the utilities are seeing fourteen times as much energy consumed during peak as during the base load rate. In their case, it is not considered a “peak” but a “spike”, that spike having been created by the use of tankless water heaters.
Now here is the real kicker. You and I might think that the grid is kind of like a rheostat. If you need more power, you turn it up, if you need less, you turn it down. Who cares if you need more power at one time, and less in another, as long as the overall usage is less, right?
Grid production is similar to continuously-running drinking fountain. It’s on, whether or not you are taking a drink.
Wrong.
That is not how the grid operates. Once you fire up a nuclear power plant, it is running full bore. Period. No up or down, just on — full blast.
You can’t just flip a switch several times a day to turn a 500 megawatt (MW) coal or gas generator on or off. They are designed for continuous running. They run the best (are most efficient and clean) at full throttle.
What that means is that much of the non-peak energy being generated, that is not being consumed, is vented into the environment. It is wasted. Not used. Spilled. Kaput. Gone.
It is like one of those drinking fountains you sometimes see in a public park or walkway — continually running, whether or not someone is taking a drink.
Now here is a statistic for you to put in your top ten things to remember about energy. In the United States, the amount of energy vented (wasted) every day by the utilities due to lost energy of non-peak production, is enough to run all of the vehicles in the country.
Bringing Down the Peak
What we need to be thinking about, therefore, to facilitate a very substantial overall planetary reduction in energy pollution, is to even out the peak-base grid demand through a combination of two things. One way is for customers to conscientiously change their usage patterns, such as to delay running washing machines and other high-demand machines until later at night.
The other is through discovering, optimizing, and installing methods by which energy from off-peak times can be stored for use during peak times. That way, utility energy generators can run at full throttle, which is where they operate the most efficiently, and the non-used energy will not be wasted. In this way, the difference between peak and base is nearly eliminated; and proportionately, the amount of waste is likewise slashed.
There will be some losses any time energy is converted from one form to another. No storage system is 100% efficient. So the complete eradication of the peak-base humps is not likely to ever be achieved. But it can be approached. Awareness of the problem is a key in resolving the problem.
Another solution is for each household to become grid-independent. Small-scale generators are much more likely to be able to handle “on-demand” production and not require continual running at the same speed. And battery storage is widely used to even out production from intermittent sources.
So are Tankless Water Heaters Bad?
In order for a tankless water heater to decrease the overall footprint of energy pollution on the planet, it needs to be used during off-peak times. Then it is contributing to an overall solution. Those who use it during peak times are contributing to the overall problem, not helping.
A General Principle
And really, that goes for all appliances. The tankless heater is but an example of a principle.
One of the most effective things people can do to do their part individually to reduce the overall dependence on oil, is to shift their energy usage patterns such that they are conscientious about when they are using their appliances. Can you do your laundry during the day, rather than in the evening? Or later at night? Turn your dehydrator off during peak hours. Perhaps you could put some of your appliances, such as a dehydrator or swimming pool heater, on a timer, to turn them off during peak hours.
If such timing devices are not readily available, let’s call upon our major suppliers to stock them and promote them. Give them a copy of this article. And while you’re at it, pass a copy on to your friends and associates. Send one to your elected representatives too!
The idea is to bring down that spike on the grid. Every bit we can do that together will mean that the utilities can cut down on their energy generation capacity, and not vent so much wasted energy during non-peak times.