Is DC Power “slow electricity”?
Kris de Decker’s Low Tech Magazine has always been a favourite website of mine; It “refuses to assume that every problem has a high-tech solution. A simple, sensible, but nevertheless controversial message; high-tech has become the idol of our society.” Now Kris looks at a subject dear to this TreeHugger’s heart: the return of Direct Current.
There are a number of reasons why DC makes so much sense today Solar panels produce DC, batteries store DC, but also these days, almost everything we have in our house except for big appliances runs on DC- our computers, light bulbs, electronics. Every one of them has to have a rectifier and transformer to turn it into low voltage DC. Kris estimates that soon we could see as much as 50 percent of the total loads in households being DC. In offices, it could be even higher.
Then there are the installation savings;
Last but not least, low-voltage DC grids (up to 24V) are considered safe from shock or fire hazard , which allows electricians to install relatively simple wiring, without grounding or metal junction boxes, and without protection against direct contact.
One of the biggest problems with DC is the cable loss; higher voltages can use thinner wires. That's why Edison had to build his power plants all over New York City instead of centralizing them. It is easy to change the voltage of AC with transformers; You couldn't do this in DC until solid state converters were developed in the mid 20th century.
However this is becoming less and less of a problem as we move toward solid state everything; it doesn’t take much energy to run an LED bulb. TreeHugger recently showed commercial installations where they were even feeding the electricity through computer cabling with Power over Ethernet. Kris also describes how houses could actually be designed to minimize cable length:
Dutch researchers managed to reduce total cable length in a house down from 40 metres to 12 metres. They did this by moving the kitchen and the living room (where most electricity is used) to the first floor, just below the roof (where the solar panels are), while moving the bedrooms to the ground floor. They also clustered most appliances in the central part of the building, right below the solar panels (see the illustration below).
Low Tech Magazine/via
In the end, Kris reverts to his Low Tech roots and notes that the best way to deal with the higher loads required by bigger appliances is to simply not use them.
This is the approach that's followed in sailboats, motorhomes and caravans, where a supporting AC distribution system is simply not an option. This is the most sustainable solution to the limits of DC power, because in this case the choice for DC also results in a reduction of energy demand.. Obviously, this strategy implies a change in our way of life.
Here he suggests that we give up our dishwasher, washing machine and tumble dryer.
No convenient and time-saving kitchen appliances like electric kettles, microwaves and coffee machines, but a traditional cooking stove operated by (bio)gas, a solar cooker, or a rocket stove. No vacuum cleaner, but a broom and a carpet-beater. No freezer, but fresh ingredients. No electric warm water boiler, but a solar boiler and a small wash at the sink if the sun doesn't shine. No electric car, but a bicycle.
This is where he gets his "slow electricity" from, perhaps a reference to what started with the slow food movement, "founded in 1989 to counteract fast food and fast life." It spread to slow cities and slow travel and slow homes, all of which consume less energy and give us more time to enjoy what we are doing.
Going off-grid direct current is certainly a slower lifestyle, and a tougher sell. With better batteries at lower prices coming on the market, it may not be necessary to give up everything to go off grid in your home, but there will have to be some compromises.
Read it all at Low Tech Magazine.