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Harvesting energy

Anonymous Mon 26 Oct 2015 16:20:14 No.51024048 View Reply Report Delete

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Will we run out of energy before we can harvest new energy sources?

There is probably enough energy for all of us, however to harvest energy we first need to invest energy. If we dont have the resources to harvest the rate of energy consumption becomes dramatically larger then the rate of energy 'production'.

Note that the energy harvasting potential depends on many different factors and those factors in turn depend on other things. Everything in the world is connected. Economic factors, political factors, workforce, rate of food production, rate of food consumption, natural disasters and global warming, rate of technological advancement, I could go on.

Complementary article
http://www.forbes.com/sites/jeffmcmahon/2015/10/18/utilities-run-out-of-time-to-adapt-to-energy-revolution/

Anonymous

Anonymous Mon 26 Oct 2015 16:24:38 No.51024128 Report Delete

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Every source of energy ever thought of has an endpoint. This is true for each and every type of energy. Even the sun will run out of fuel eventually (expected to go out 5 billion years from now).
Renewable energy sources are those that are naturally replenished at a rate greater than the rate that we are using them.
The definition never says anything about them being unlimited forever.

Now that I've established that they can die out, the second part of the question:
The timeline for their depletion depends on many factors of which most importantly is the amount of 'pressure' we humans exert on the resource.
For example coal & natural gas are technically speaking renewable resources but we are using them up at such a high rate that the nature isn't able to replenish them.
Also effects of global warming have to be taken into account. For example tidal energy can be converted into electrical energy but due the global warming, the sea levels are rising rapidly and any installment we setup for generation on the shore may get fully submerged within a decade.

Hydro involves damming rivers and storing water in reservoirs. These reservoirs trap sediment, silt up, and become less effective at storing water. Many of these systems have lifetimes of ~50--200 years. Then they need to be torn down, dredged out and rebuilt.

Wind is potentially more sustainable than hydro as there is no silting problem. However, the machines have a lot of moving parts and the 100-year worst-case wind storms are pretty severe. So far, few windmills have lasted even 20 years and the wind farms that I've seen that are 20+ years old have essentially no operating old wind machines. These too will need continuous rebuilding.

Solar collectors are even more fragile than wind collectors. The solar panels on my house lasted less than 10 years. Many panels are specified to degrade 3--5% per year. These too will need continuous rebuilding.

>cont

Anonymous

Anonymous Mon 26 Oct 2015 16:28:06 No.51024183 Report Delete

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Hydro, wind, and solar depend on solar output and weather patterns. In the next 50--100 years, global climate change may drastically change the effectiveness of these solar energy collection systems. But, given a steady supply of raw materials (steel, concrete, aluminum, glass, etc) we can keep rebuilding them for millions of years. I'll call that renewable, but not necessarily sustainable

Tidal energy systems collect energy from the moon's orbit. The moon pulls against the ocean's water, lifting the water and slowing the motion of the moon. The moon's orbit will outlast the sun's solar output, so it's "renewable". But the ocean is a harsh environment for machines. Big ocean installations require a lot of maintenance to last 20--50 years. These machines will need a larger influx of maintenance and rebuilding materials than either wind or solar.

Biofuel is turning food into fuel. We talk about using cellulose, but we really use sugar, corn, and palm oil. This is a subsidy scheme for farmers. Operating a farm requires huge amounts of diesel fuel to run tractors, harvesting equipment, to process the materials and transport them to market. The energy return on investment of biofuels is terrible compared to most other sources. And then there is soil depletion and competition for land resources between farmers and nature. Bio fuels are not sustainable. We need land for feeding people, not for feeding our SUVs. Not renewable!

Geothermal is a weird one. It's really mining ancient heat produced by nuclear decay inside the earth. When holes are drilled into rock and the rock is cooled, the resource is depleted and takes many decades to re-warm. Not renewable and not sustainable!

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