Friday, September 22, 2023

Climate change is about entropy

 Veritasium has a briliant video explaining entropy

Entropy always increases if anything at all is happening. It is tempting to think that the universe wants to increase entropy as fast as possible. While this is not true, it often seems like it is. So I'm going to personify the Universe with that motivation.

Living things, including us, are little islands of low entropy. We use energy to create that low entropy state while increasing the entropy of the wider environment at a faster rate than would otherwise occur. It seems as though the Universe invented life to speed up entropy production. Then it invented intelligent life to speed it up even more. And now it has invented social co-operating civilised life forms to really put the foot to the floor of entropy production.

When the carbon was in the ground and the oxygen was in the air, that was a lower entropy state. When we combine the carbon with the oxygen we increase entropy. What we get directly is energy, and what we do with that energy is to create pockets of low entropy, which we call civilised life. Whether the pocket of low entropy is a car or a baby or a movie, it is in an organised and differentiated state which is the complete opposite of the high entropy mess that the Universe will eventually make of everything.

It won't be enough to stop burning carbon, we are going to need to reduce the carbon in the air to get back to a comfortable interglacial climate. The correct way to look at this is that we want to reduce the entropy of the atmosphere. The reverse of what we have always done. You need a lot more energy to reduce entropy than you got out of increasing it in the first place. Where is that energy going to come from?

The Sun sends us low entropy energy and the Earth emits high entropy energy, and this allows life to make its pockets of low entropy. We can use power from solar and wind and hydro to take more and more of that bounty that life on Earth depends on. Luckily we don't have to do this.

In the enormous energy released in supernova explosions and other astronomical events, tiny pockets of low entropy are created in the form of radioactive elements. We can extract that low entropy by making those atoms decay sooner than they naturally would. That is fission energy. We can also mimic stars by increasing the entropy of small atoms by merging them into slightly bigger ones. That is fusion energy. These are energy sources that the rest of life on Earth doesn't use. By switching to these energy sources and giving the sun back to other life forms, we can recreate the bountiful world that we have gone so close to annihilating. Let's do it.

Saturday, September 9, 2023

Flood-proof Moveable Buildings

 Flood-proof Moveable Buildings

There is a confluence of problems relating to housing:

  • A warming world brings more rain, and recent experience suggests that it might come in fewer heavier events. And people like to live near rivers and lakes and in fertile valeys. 

  • People also like to live near the ocean, but some places are prone to tsunamis, and no coast is immune. And rising sea levels are increasing the flooding danger from storm surges.

  • So we have desirable locations, some with current service infrastructure, where conventional housing can no longer be insured, which is required for obtaining a mortgage.

  • Meanwhile jobs come and go at different places as new economic activity arises and declines.

  • There is also increasing awareness that rivers should not be corralled as much as they have been, but should be allowed to change course and to flood. There is a need to fit human occupation in with the natural life of the river.

Homes that float seem like an expensive solution, but maybe not.

Let's start with the simplest version: the mobile home. By this I mean something like a very large caravan. To make it floatable we put the door, and all openable windows, well above the water line when floating, while also making them well sealed when closed. We don't moor it like a houseboat. Instead we constrain it with poles firmly embedded in the ground on four sides so that it floats up and down in the same place.

Relative to a normal house of the same size this is intrinsically more expensive. However there is a big advantage in that it can be manufactured in a factory. It can be transported by truck, but another big advantage is that it can be towed by water to, or close to, its destination.

Indeed for houses that are going to be transported to their destination entirely by water they need not be constrained to be narrow enough for trucking. This might be particularly suitable for housing in man-made marinas as well as on river banks.

Where larger homes are required but transport by truck is needed, then they can be constructed in 2 or more parts, designed to be bolted and welded together.

Attachment of services to the home can almost all be done above the water line. The exception is waste water, which normally has to flow away under gravity. There are pumping solutions which will allow that connection to be above the water line. Alternatively there needs to be a seal that will very firmly and reliably and automatically close when flooding raises the house.

Moveable housing such as this allows for flexibility when a river changes course after a flood. The owner whose land has disappeared can be automatically allocated land where the river used to run. There will be the problem of new services, but since this will be a fairly rare occurence it can be covered by insurance.