I've been reading articles and taking webinars lately about the smart grid and there is definitely a lot of information out there. A lot of it is very interesting and there are definite pros and cons that seem to repeat both in the articles and then again in the comments by readers below the articles. Their seems to be a lot of controversy surrounding the smart grid and I’d like to discuss it in greater detail in a series of blog entries.
First of all, to define my bias, I must say that I am a proponent of change and am therefore all for the smart grid. I feel that any change to the old electromechanical meter I have on the side of my house is for the best, as well as the antiquated flat rate based on time of year pricing my electric utility charges me. Also, as a power engineering professional I have designed replacements of electromechanical relays and meters both on the utility and private client side with new microprocessor (think of computers and internet) based relays and meters and can see the advantages to both. Additionally, the utilities will have better control over certain things like voltage sag and outage mitigation that will allow them to actually increase their system efficiency which will in turn require them to produce less power, burn less fossil fuel, etc.
For the first entry in the series, I’m going to discuss TOU pricing and whether it is fact or fiction that it will save the consumer money.
Does TOU (Time of Use) utility power pricing save the consumer money?
TOU is when the utility defines rate periods based on their projected peak power usage part of the day. Say for example the peak power usage is between 10am and 6pm, they would charge a higher rate than between 6pm and 10am. The utility can also add additional rate periods, like overnight or weekends as they see fit. The rate on the off-peak period is a really low rate. This type of pricing requires a digital meter that will log the power usage at certain times of day, so that they can bill you accordingly. This is what I will refer to as the ‘smart meter’. In one article, I’ve seen this compared to the way cell phone minutes are priced, but don’t expect to get discounts for mobile to mobile or for family plans.
In theory and according to supply and demand economics, to save the consumer money, items such as large appliances should be turned on only after the price of power use has dropped. This action is controlled by the consumer and with a change of consumer routine, may actually work. I say ‘change of routine’ because I would imagine most people do what I do, or my wife does, which is turn the appliance on after it is filled; such as the dishwasher, the washing machine, the dryer or even the electric oven. Some appliance companies are actually implementing this into their future products to work with smart meters, which will allow the appliance to turn on by itself when the rate drops based on a signal received from a smart meter. This ‘change of routine’ will require getting used to and if properly managed can lower your electric bill. After all, we did start turning lights off after we left rooms, right?
The following are my concerns, however. During the summer there are certain things that I have to run during the higher rate periods such as my pool filter and the air-conditioner. Will running these appliances drastically increase my electric bill? I thought about this question for a while and I think I have a response, YES. These two items, because they run for long periods of time, are huge power consumers and will be expensive to run in the high rate periods, which will definitely increase your bill. The amount of time and power they consume during the high power rate periods can be adjusted, however.
A pool filter should be sized to re-circulate the entire contents of the pool within 10-12 hours. Most of them are oversized and do in 8 hours, though. Also, it only has to re-circulate the water once per day, so why not do it overnight, when the power is cheap! I haven’t tried this, but I would imagine the water would get pretty dirty and the money saved on electric would probably go towards chemicals, but maybe not. On another note, I’ve also seen a similar justification for changing to a two-speed filter pump. If you put it on the lower speed and run it for 12 hours, it will do the same thing, but cost less money in power. In math: normal speed=10A@120V, low speed =5A@120V. Normal Speed =(10A*120V*8hours)/1000=9.6KWh, Low Speed=(5A*120V*12hours)/1000=7.2KWh, which is a savings of 25%. Before doing this I would check that the filter and pump can accommodate the system head at the lower speed and still re-circulate the entire contents of the pool in less than 12 hours. Some utilities even provide rebates for going to a two-speed or variable speed pump. If you do this than maybe you can run a half or quarter cycle during the high rate period.
The thermostat on the air-conditioner could be changed (assumes central a/c) to a programmable type ($35), which will allow you to set the temperature higher when you’re not home or even during the higher power rate periods (if you can bare to be a little uncomfortable). If it has more than one zone, maybe you can increase the temperature on the parts of the dwelling that are not in use during the higher rate periods (like the bedroom zone), and if it has variable speeds, maybe putting it on a lower fan speed during the high rate periods will help, see calculation and justification above in the pool fiter paragraph.
To sum this up, it seems that if handeled properly by the consumer they can save some money. If they do nothing , their bill will go up. The next question should be, is TOU pricing fair? Well from a business standpoint, I'd say yes. It's simple supply and demand economics in a capitalist society in which consumers are paying for a service (supply) and based on the consumer usage (demand), the power company is charging a publically disclosed rate. From a consumer standpoint though, Its unfair that our routines will have to change through no action of our own.
