The more I think about it, the stranger the idea of an electricity grid seems to me.
There are two kinds of energy grids people generally talk about. The first is the traditional kind — large quantities of power delivered from a faraway power station to your home. In the second case, there’s a “smart grid” where there are smaller power generators everywhere and they “share” this power around. For both of these grids, an argument of “base load power” kind of wafts in and out.
The more I think about it, the stranger the idea of any kind of energy grid sounds. I say this having been in India and knowing just how annoying it is to lose electricity for several hours a day. In fact, considering Indian “grid-connected” electricity is so unreliable, it makes me wonder why people bother connecting to it at all. Think about the things in your house that require electricity.
Firstly, let’s get heating out of the way. The vast majority of household energy is wasted on heating. I say “wasted” because heat is literally the easiest and most efficient thing to generate. In contrast, electricity is really really hard to generate — almost all generators “throw away” a lot of heat in order to generate a precious bit of electricity. To go through all that work just to throw it all away as more heat is a level of waste bordering on insanity.
Cooling is a different matter, but often a huge amount of cooling happens due to bad home design. Either the house is inefficient at keeping hot air out, or it is bad at holding thermal loads where they need to be. Before air conditioners, people often used water features to keep an area cool. This can still be seen in public places — water keeps the area nearby cool. Similar ideas can be used alongside a good thermal load to keep an area cool. Other than a small 10-20W load to keep air moving inside a house (50 – 100Wh per day) cooling should not be “a thing”.
What I’m saying is that heating water, cooking food, and heating rooms, should be achieved directly through energy sources, such as gas, coal, wood, or other easily transportable fuel. For most households, this will probably reduce electricity usage by between 2/3 and 4/5. If you have a gas connection, I’m saying you should immediately use that, and then consider the rest of this article.
A second common source of electricity used today is for lighting. In the past, each lightbulb was around 100W. That figure seems shocking to me now, but that’s how it was. Today, all the lights in my entire house would total 100W. I’d estimate I only use about half that for general usage. If I had “smart” lighting which would dim (but not switch off) if no one was around, I’d halve that usage again. That’s 25W to light a house at night. Considering a house would only see about 4 hours of lights usage, that’s 100 Wh of energy required to power the lighting in your house.
However, you should probably actually use less than this. If you think about how lighting affects sleep, your lights should start to dim as the night wears on, gently lulling you to sleep. Ideally you would “want” to use closer to 50 Wh for a healthy lifestyle, but where you draw the line exactly will differ from person to person. Either way, a small lead acid battery will probably suffice for that sort of usage.
Another major source of electricity usage is in the kitchen. Even if you don’t use electricity for heating, chances are you’ll still want to use a microwave oven, blenders, toasters, and food processors. What’s worse, these things are often very high power devices — 600W, 1200W, are all common power ratings for these things. Thankfully, you often only use them for a minute or so. Overall, another 50Wh ought to be enough, per day.
Then there’s the laundry, which could use similar amounts of power but for two hours. On the one hand, this might be around 2kWh, but on the other hand, you can probably wait a day or so to use it. Vacuum cleaners have the same usage patterns and power draw. If you were using Solar, for example, you could just wait for a sunny day to use the washing machine or vacuum, and you could also “redirect” power from other uses to power the washing machine. The important thing here is that you don’t need to store the power for using the washing machine, just use whatever power generation method you’ve already got set up.
A reasonable sized fridge, however, would use close to 1 – 2kWh every day, and this is non-negotiable. Even for a country with a lot of sun, you not only need to keep a fridge working all day, you also need to ensure that you don’t end up in a situation where the fridge doesn’t have power. This would mean you’d need a 10 – 20 L Lead-acid battery to keep a fridge going.
However, think of a fridge, its design, what it contains, and why. The freezer is necessary but it’s also often fairly efficient and small. A good fridge would be designed to have the doors pointing upwards, and sliding to open. Ice-cream drawers are a bit like that. Finally, the things you keep in a fridge are often fresh food and leftovers. Judicious use of space and controlling your food could mean that your fridge could take as little as 500Wh, which is a far more comfortable 5L lead-acid battery.
This brings us to an area that’s undergoing a huge amount of change — computing and entertainment. In the past, TVs (even LCDs) were huge power wasters, often taking 100 – 200W. Today, not only are TVs using far lower power, TVs are kind of becoming obsolete. Entertainment is far more “personal” today — people using Tablets or laptops or phones. Even newer consoles are hugely more efficient than the the recent past — the PS4 uses around 100W of power compared to the PS3’s 300W. Hopefully if trends like the PS Play take off then we’ll have consoles which absolutely sip power, maybe 5 or 10W. In addition, computers are increasingly laptops, which are by necessity lower power.
Even more interestingly, many of these devices have battery backup, and there’s a glut of them. If you don’t have the power to run a TV, you can move to your laptop. With this in mind, anywhere between 100-200Wh would be well and truly sufficient to entertain yourself for a night. With a little bit of self control.
So let’s figure this out in terms of supply power and storage power. I’m going with my ‘ideal’ scenario, the ‘worst case’ is an exercise for the reader. For supply power, the system needs to supply around 1kW to power a vacuum cleaner or washing machine (or cooking for daytime cooking). This is only for a couple of hours per day. The rest of the time is spent storing energy. This means around 6-8kWh of storage per day. It’s also a fairly modest solar power installation.
The biggest draw is for the fridge — 500Wh per day. Then 50Wh for light, 50Wh for cooling, 50Wh for night-time kitchen power usage, 100Wh for entertainment. This adds up to 850Wh, let’s make it 1kWh. Firstly, this can be done with around 10L of lead-acid batteries. It’s a lot, but not unheard of. Hybrid cars already have batteries in that ballpark. You could double that number and get roughly the worst case scenario or a little more breathing room.
In the end, all of this can be had for between $5-10k. This is a very short RoI, and minimal ongoing costs. We can also expect these costs to go down fairly quickly over time. Importantly, it can mean a house or community gains a significant amount of flexibility when deciding how to set up its housing. This is doubly true if instead of using a gas pipeline, gas cylinders, wood, or coal is used instead. It can also prevent bushfires.
The real reason I’m thinking about this is because I’m going through the math of the earlier idea of “a fireproof house”, but also because I’m thinking about this from a policy perspective — Is it completely foolhardy to put money into electricity distribution networks and large power stations? Shouldn’t this money instead be put into a completely distributed way of generating power? Is the idea of an electricity “network” completely overrated?