Technology to create energy for a village of 200 people long term

Question

Looking for options with at least some grounding in science:

Several hundred years in our future, a group of wealthy philanthropists lavishly funded a colonisation project designed to create a Utopia. Their theory was that human violence is a cultural phenomenon, which occurs because of traumatic childrearing practices, poor social structures, and generational contagion.

The controlling AI found a suitable planet, did some modest adjustments to make it more habitable, seeded it with genetically-engineered plants which naturally produce a vast range of medicines (including contraceptives), and human volunteers raised the first generation of native-born humans without any knowledge of the colony ships, or the history of the species. Just general knowledge of biology, chemistry, geology, etc, and all the specific knowledge of how to live on this particular world.

When the first generation were old enough (the second generation was successfully raised, and the third generation was being born), the human volunteers gradually withdrew, one by one, until there was nobody left on the planet with any knowledge of the colonisation.

Part of the theory was that humans evolved to live in villages of less than 200 people, so the society was organised into villages, approximately a day's walk apart, which practiced permaculture.

The centre of each village is the Hearth - a building which provides shelter, cooking facilities, and apparently endless energy. The hearth has an oven, so that food can be cooked, and ceramics can be fired. It doesn't generate that heat by burning stuff.

There are enough Hearths on the planet to sustain the population that the AI calculated would be manageable for the ecology. They are scattered throughout the tropical and temperate regions.

My question is - given that there is sufficiently advanced technology to do terraforming, shall I just say they tap into geothermal energy through a planet-wide grid, or is that scientifically laughable?

Additionally, I want these things to be massively durable, lasting for thousands of years without maintenance from the humans. Is that possible without the ongoing presence of the AI and a bunch of maintenance nanobots? Solar panels won't last that long.

Alternative solutions to the Hearth problems very welcome.

Assessments of the theory of the Utopian philanthropists not necessary - the validity of that theory is the subject of a series of at least nine books!

Answer 1

Power Plants

seeded it with genetically-engineered plants which naturally produce a vast range of medicines

Keep the idea of genetically-engineered plants going and have your colony rely on organic technology for power generation. Organic technology has several advantages over normal technology which would allow it to meet the requirements you are looking for. Nanobots and machines tend to rely on metals and rare elements, which tend not to be evenly distributed in the mantel of a planet. Not to mention rare metals tend not to be easily accessible and requires a lot of processing to make them useful. As such even with self repairing nanobots they would be hard pressed to find the materials locally to maintain their Hearth.

Power Generation

Have the plant use photosynthesis to generate energy to keep itself alive and rely on other sources of power to generate power that can support the village. Since plants typically have easy access to water, I recommend hand waving an organic version of a fusion reactor powered by deuterium to supply power to the village. The power generated would run near the surface of special areas of the plant where villagers could stab in power taps to supply power to their various devices.

Plant Life Cycle

Since it is organic, it can self repair and heal on its own, also it could be genetically engineered not to die from old age. The power plants could still be killed by a natural disaster, accidents, or intentionally. To counter this have the plant produce seeds. The plant would keep at least one seed stored in itself at any given time so that if it dies the seed could start a new power plant. The plant would also have seeds easily accessible to humans so that if they find a place that is missing its power plant for whatever reason, they could plant a new one themselves.

Answer 2

Radioactive Diamond Batteries

Diamond naturally generates electricity when exposed to radioactivity. So, radioactive diamond batteries are made by forming carbon-14 into diamond and encapsulating it in regular non-radioactive diamond.

These diamond batteries have a very specific purpose – low power and extremely long life. A standard twenty-gram non-rechargeable AA battery stores about 13,000 Joules and will run out of power in about 24 hours of continuous operation. One diamond with one gram of carbon-14 would produce 15 Joules per day, much less than an AA battery.

But the power output of the diamond battery is continuous and doesn’t stop. The radioactive diamond battery would still be putting out 50% power after 5,730 years, which is one half-life of carbon-14 or about as long as human civilization has existed. During this time, the diamond battery would have produced over 20 million Joules. And would produce another 10 million during the next 5,730 years.

So, if a diamond grid were built as one single piece that spanned the entire planet, connecting all the Hearths together, it's possible you could get enough energy from the diamond to meet the population's needs. The grid would need to contain enough radioactive material that it's output would be sufficient, so perhaps diamond mountains could be part of the grid, or massive underground diamond banks, or perhaps the planet itself could be made of diamond inside, with proper earth-like terraforming on the surface layers.

Refueling

Perhaps if you want the society to last more than the lifespan of the batteries, you could have the philanthropists periodically replace of spent diamond with fresh diamond every 5,000 years or so. This could be done perhaps in relative secrecy, or perhaps they could be viewed as gods. Perhaps even if you had the entire planet made of diamond, the repacement teams could terraform out the old diamond and replace it with fresh diamond.

Feasibility

The feasibility of this would depend on how much energy you needed for your society--that would dictate how much diamond would be needed. So, the less power you need, smaller the diamond units would need to be, and so the more plausible it is to replace them easily in the future.

Nonetheless, one can assume that your scientifically advanced philanthopists will continue to technologically advance over the first half-life of the diamond, so that's 5,000+ years for them to develop much larger scale terraforming for replacement of the spent diamond. So, even if you had the entire planet made of diamond inside, perhaps in 5,000 years or 10,000 years, the philathropist's technology would be sufficient to replace the spent diamond.

Answer 3

Let's start by estimating how much energy each village would actually need.

Now I'm assuming when you say the Hearths generate "apparently endless energy" you mean they create enough to constantly supply each village.

If this is the case first we need to figure out how much energy they would actually need.

Since you didn't include any figures apart from the understanding that these villagers live generally modest lives let's start by taken the world average(the sheer poverty of most of the world should balance out the exuberance of the west) energy consumption per household per year: about 3500Kwh. Let's say each village has 35 households(Which can leave room for each to house roughly 6 people, perhaps 2 grandparents, 2 parents and 2 children) and 5 additional "household like" buildings(schools, activity centers, etc...) so that's 40 "households" total or a total consumption of 140,000Kwh or 140Mwh per year. Easily obtainable.

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Now let's explore some possible energy sources.

You want these hearths to last several thousands of years without maintenace, then we have to already eliminate several energy production methods: namely nuclear and fossil fuels like coal and oil.

And the issue with your idea for a geothermal grid is that your villages are spaced too close, you'd have to hope for a viable geothermal fissure about every 50 miles which isn't really possible unless your planet is really different to ours(there is also the issue with shifting ground which would cause many to become unusable without adjustments after only a few centuries).

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Finally here's the problem, not energy production, but durability.

No matter what energy production method you choose a small earthquake or even just wear and tear could easily dislodge a vital component of these hearths rendering them useless without that tiny adjustment.

Even if we do recognise that this future's technology is much greater then our own it would still have to be so advanced to be able to ensure that every single hearth would remain operational over millennia of abandonment; to put this in perspective almost all(with the exception of photovoltaics which can theoretically last longer) current power plants are designed to last less then a century, that with constant maintanance, part replacement, supervision and industry expertise.

If just one of these hearths failed that would surely mean the affected villagers going to war with the nearby villages for the needed resources and entirely defeating the whole purpose of the planet's configuration.

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Face it, even for the far future this simply isn't very feasible.

Answer 4

Additionally, I want these things to be massively durable, lasting for thousands of years without maintenance from the humans. Is that possible without the ongoing presence of the AI and a bunch of maintenance nanobots?

If you'd like an example of what is capable of lasting thousands of years without maintenance from humans, we can showcase our inventory

There is literally no modern technology today which is even perceived as being able to generate energy for thousands of years. Sure, we can get nuclear isotopes that will generate radioactive energy for that long, but the machinery to turn that into energy will certainly break down.

Of course, you do have a group of people that have literally flown to another planet. This either involves Faster Than Light travel, in which case all bets are off and you can just handwave the Hearths, or it involved a multiple-thousand year trip through space, in which case they've figured out how to build things to last!

I'd say, given all of that, the effort of making a power source for a few thousand years is literally peanuts. I'd recommend handwaving it and never looking back. You have far more contentious sources of conflict regarding the utopian claims at the heart of the book. Your readers should be more than willing to overlook an energy source or two.

Answer 5

Given current technology there is no energy source that will last for thousands of years without maintenance. Geothermal stands a good chance of being destroyed for reasons that others have given above. Plus, geothermal tends to be finicky and maintenance-intensive.

Solution 1: Long-duration solar energy

Solar power has the benefit that there are no moving parts. You could also keep every element of the power system in or around the hearth, which would mitigate the risk of damage by earthquakes and whatnot. On the other hand, those solar panels are vulnerable to weather events- hail stones, severe storms, etc. You'd also have to make sure they never get too dirty or overgrown by vegetation.

The technological leap here is that solar panels degrade over time. On a modern solar panel you might see roughly 1% to 0.5% reduction in efficiency per year. This means that a 10 year old solar panel would produce 10% less energy than the day it was installed, where a 30 year old panel might produce 30% less energy. On top of that, you need batteries to store energy for overnight use, and modern batteries wear out over time and eventually lose the ability to hold a charge.

Given that you've got space ships, you can probably hand-wave the technical issues. Solar energy and battery energy are both really intense areas of research right now. A good hand-wavy answer would be that the panels and batteries are designed to "refresh" themselves every 1000 days by totally charging themselves and discharging themselves. That would require a little microcontroller, but not an AI.

Solution 2: Nuclear Energy

Modern nuclear energy requires a lot of maintenance, but people have been talking about Small Modular Reactors for some time now. Some of these are designed to be self-sufficient and self-contained machines that are fueled at the factory, and are then only limited by the need for periodic refueling. One highly experimental design called a Traveling Wave Reactor is supposed to solve the refueling problem by packing enough fuel into one reactor to "burn slowly" for upwards of 100 years.

These are also relatively compact, as far as nuclear reactors go, and could be co-located near the hearth, minimizing the risk from earthquakes and geologic activity. They could also be buried, minimizing the risk from severe weather.

The leap for your story would be upgrading the traveling wave design to store thousands of years of fuel rather than a hundred, which seems pretty reasonable to me given an advanced society. It would run out eventually (unlike solar or geothermal), but consider how much progress we've made in the last 10,000 years. At some point the hearths would stop working, but by then these people may well have their own scientific understanding of electricity.

Answer 6

EDITED to account for missing constraints

Locate Hearth above giant bats caves, and add beneficial microorganisms that decompose their refuse to , among other things , methane. By carefully designing system of fissures you can supply it to hidden burning chambers (to hide fire) beneath cooking ovens. It would also supply heat for living quarters.

Answer 7

Hearth is the tip of a single large rod of metal extending down to where the crust is very hot. It conducts heat up. The top stays hot. You can boil soup on it.

Don't let the kids bump into it! It's hot!