DIY Electricity
03/09/12 16:38
Part of preparing for winter this year is preparing for power failures. Although the “last mile” of phone, cable, and power wiring to the houses in this part of town is all underground (a big improvement over New Hampshire, where even the posh neighborhoods were festooned with old-fashioned telephone poles and overhead wiring), that doesn’t prevent lightning from striking a substation or other types of power failures. So we’ve got our own source of short-term electricity.
There are two types of small-scale generators on the market. The older-fashioned ones are basically gasoline engines that spin a much smaller version of the bundle of coiled wires that generates electricity at Niagara Falls or the local coal-fired power plant. The gas engines are fairly efficient: when the power goes off, you flip a switch, open the choke, and give the starter one pull. Then you plug in your lights and appliances and you’re off to the races.
The newer type of generator is called an inverter. It is advertised as “broadband” technology, to the old generator’s “DSL.” But this isn’t a useful analogy, because the two devices do quite different things. Inverters, as the name implies, are all about changing the form of energy: specifically, they change alternating current (AC) to direct current (DC), and vice versa. The point of this is that DC can be stored in batteries, whereas AC can’t be stored at all (which is one reason our national electrical grid is so complicated, centralized, and inefficient — but that’s a story for another time). As a result, inverter type standby power supplies incorporate batteries as well as motors. They use the motors to charge the batteries, and the batteries to power your appliances. (for a more detailed explanation by a sales-guy, look here)
One result of this process is that the inverters are often much quieter. The motor isn’t constantly running, so you’re not using gas the whole time and you don’t have to listen to the constant hum. And you’re not running a 3500-watt motor to power 350 watts of load, so in the long run the inverter is more fuel-efficient. Another advertised benefit is that the power is “conditioned” as it goes through the inversion process, so you get a very smooth wave-form instead of the noisy, jagged signal produced by the generator. This is seen as beneficial because computers and other high-tech devices prefer “clean” power. A third result is that inverters are often several times the cost of a comparably-rated generator.
Unlike a lot of the people who buy generators (many of whom are campers, I guess, on the basis of the way these things are marketed), I’m more concerned about keeping the fridge, freezer, lights, water heater, pump, and (in a longer term outage) washer and range working, rather than my computer or entertainment center. I figure if there’s a major outage, I’m probably not going to be surfing the web anyway. And as far as clean power goes, we already have surge strips between the wall and the computers.
Also, if I’m buying a generator, I’m mostly interested in its generating ability. Batteries are something else. When I want to store electricity, I’ll buy batteries from a battery specialist, not from a small engine manufacturer (sorry, Honda). And I may be interested in doing that at some point down the line. Wind and solar installations would both use an inverter and a bank of batteries — so it seems like it would be smarter to get them when the time comes, and think of the generator as just another source of raw power into the system. That will be the real, permanent DIY electricity story — this is just a small step on the way to that final goal.
So in the end, we got a generator that should keep the household appliances and lights on if the grid goes down temporarily. It will run for about half a day on a tank of gas — so in addition to the unit itself, I need to store fuel. I’ll be keeping and running it outside the main house (carbon monoxide is an issue as well as noise), and connecting to the house using two 100 foot extension cords. This unit has two 120 volt plugs, as well as a 220. So if there was a longer-term outage and we got tired of eating leftovers out of the microwave, we could connect the kitchen stove. Now I just have to track down where the well-pump gets its current from, and make sure I can attach a couple of the basic household systems so we can function when the lights go out.
The newer type of generator is called an inverter. It is advertised as “broadband” technology, to the old generator’s “DSL.” But this isn’t a useful analogy, because the two devices do quite different things. Inverters, as the name implies, are all about changing the form of energy: specifically, they change alternating current (AC) to direct current (DC), and vice versa. The point of this is that DC can be stored in batteries, whereas AC can’t be stored at all (which is one reason our national electrical grid is so complicated, centralized, and inefficient — but that’s a story for another time). As a result, inverter type standby power supplies incorporate batteries as well as motors. They use the motors to charge the batteries, and the batteries to power your appliances. (for a more detailed explanation by a sales-guy, look here)
One result of this process is that the inverters are often much quieter. The motor isn’t constantly running, so you’re not using gas the whole time and you don’t have to listen to the constant hum. And you’re not running a 3500-watt motor to power 350 watts of load, so in the long run the inverter is more fuel-efficient. Another advertised benefit is that the power is “conditioned” as it goes through the inversion process, so you get a very smooth wave-form instead of the noisy, jagged signal produced by the generator. This is seen as beneficial because computers and other high-tech devices prefer “clean” power. A third result is that inverters are often several times the cost of a comparably-rated generator.
Unlike a lot of the people who buy generators (many of whom are campers, I guess, on the basis of the way these things are marketed), I’m more concerned about keeping the fridge, freezer, lights, water heater, pump, and (in a longer term outage) washer and range working, rather than my computer or entertainment center. I figure if there’s a major outage, I’m probably not going to be surfing the web anyway. And as far as clean power goes, we already have surge strips between the wall and the computers.
Also, if I’m buying a generator, I’m mostly interested in its generating ability. Batteries are something else. When I want to store electricity, I’ll buy batteries from a battery specialist, not from a small engine manufacturer (sorry, Honda). And I may be interested in doing that at some point down the line. Wind and solar installations would both use an inverter and a bank of batteries — so it seems like it would be smarter to get them when the time comes, and think of the generator as just another source of raw power into the system. That will be the real, permanent DIY electricity story — this is just a small step on the way to that final goal.
