Harnessing the energy of forest fires

[ScienceNostalgia101]

Year after year, somewhere in the world, its forests are on fire. There's a lot of talk about people displaced, but not about energy that went to waste.

 

Is it at all possible to set up a network of pipes carrying seawater, (and/or giant enclosed containers of the stuff; obviously not tall, just long and wide) such that any burning forests underneath them would force the resulting water vapour into a pressure release valve underneath a steam turbine?

 

Apart from any initial investment in such a project, would there be significant maintenance costs?

[Country Boy]

What about the cost of moving those pipes to the various forest fires? Not to mention the difficulty, and danger of placing those pipes in the middle of the fire.

[Area54]

Apart from any initial investment in such a project, would there be significant maintenance costs?

You may recall that steel did not react well to heat in the twin towers. Form the appropriate conclusion.

 

More to the point the initial investment would be vast and never recouped. Try some back of the envelope calculations to satisfy yourself.

[ScienceNostalgia101]

The idea was to build it prior to the forest fire, in anticipation of where they typically are. @ HallsofIvy

 

The twin towers weren't filled with water, though. Wouldn't water flow to wherever the water level was dropping in the pipe? If not, why not, and if so, why wouldn't that constant contact between water and steel resist temperature increases beyond the boiling point of water? @ Area54

 

I have no idea how much it costs to build an elevated pipe or a wider, more rectangular container of water, nor where to start on that one, so I was hoping someone more familiar with either could fill me in on this.

Edited July 16, 2017 by ScienceNostalgia101

[mistermack]

Apart from the initial costs? How come they don't count?

 

The cost of running stainless steel pipes over all of the forests would be ludicrously expensive.

And salt water would not be good for the land. And yes, the running costs would be incredible, for such a tiny return.

[Area54]

 

The twin towers weren't filled with water, though. Wouldn't water flow to wherever the water level was dropping in the pipe? If not, why not, and if so, why wouldn't that constant contact between water and steel resist temperature increases beyond the boiling point of water? @ Area54

 

I have no idea how much it costs to build an elevated pipe or a wider, more rectangular container of water, nor where to start on that one, so I was hoping someone more familiar with either could fill me in on this.

Engineers are good at overcoming complexities, but this is (nearly) always at a cost. There are so many complexities involved in this proposal that, without doing any calculations, the gut screams "No!".

 

Forest fires are very hot. I lack your confidence that the water would avoid reaching boiling point. That is going to create all kinds or pressure and flow problems that demand complex valving and control systems, not to mention piping that can tolerate higher pressures and one heck of a temperature gradient across the steel.

 

Forest fires are undpredictable. This will create large and constantly changing patterns of temperature within the affected area. That adds to the control complexity already meantioned.

 

Forest fires are rare. In a given patch of forest they occur decades, often many decades apart. So, you build your infrastructure and wait thirty years (with ongoing maintenance) until you can reap the brief energy reward.

 

The intent of your proposal is noble. The practicalities seem to me to make it unworkable (in the extreme).

[ScienceNostalgia101]

This year's California fires reminded me of this subject. California's a state that seems to be on fire especially often.

 

I've since come up with another option. What about, instead of pipes, a large container, with a base and walls, (and maybe a roof) to boil the water? If they could make it thick enough to withstand the heat, would it be more practical to use the boiled water directly (cooking, coffee, etc.) or to put a hole in the roof to force the steam through it to turn a turbine?

[Bender]

3 hours ago, ScienceNostalgia101 said:

This year's California fires reminded me of this subject. California's a state that seems to be on fire especially often.

 

I've since come up with another option. What about, instead of pipes, a large container, with a base and walls, (and maybe a roof) to boil the water? If they could make it thick enough to withstand the heat, would it be more practical to use the boiled water directly (cooking, coffee, etc.) or to put a hole in the roof to force the steam through it to turn a turbine?

No.

[J.C.MacSwell]

How expensive is it (rhetorically speaking) to build a system where you have a chance to optimize the use of the waste fuel (wood being an example), concentrated and controlled at a particular point? Now compare this with something that is random and dispersed in both time and space. What chance do you have of a fleeting return, where you can point and say "hey, that was temporarily recouping some of the investment faster than the interest was mounting on it"

[ScienceNostalgia101]

That could go either way, though. With a woodstove, you don't need as big a container of water, but you need to select the wood and transport it to where it is being burned. With a forest fire, you'd need a HUGE container of water... but the fire comes to you.

 

Cast iron's apparently $1.29 per kilogram... how thick would a cast iron container need to be to withstand flame while holding water? (I could probably derive a function between surface area and cost/revenue from that... I also realized now that perching something rectangular would also be wasteful, as it makes it difficult to relocate from the forest one just torched to a forested one, so whatever I come up with will be either cylindrical or spherical.)

Edited August 9, 2018 by ScienceNostalgia101

[Sensei]

On 16.07.2017 at 1:53 AM, ScienceNostalgia101 said:

network of pipes carrying seawater,

Seawater contains contamination e.g. Na+ Cl- Mg2+ Ca2+ and so on..

If you let seawater to flow through pipes, contamination will cause corrosion of pipes..

Release of seawater on the land in large quantity would result in devastation of the land, as it's too salty for plants.

 

[ScienceNostalgia101]

Gah, forgot 2nd time around that I even specified saltwater 1st time around. The idea was that it'd be a waste of fresh water to use it or this and I'd like to use something otherwise useless. Even so, the idea is at the very least use something other than tapwater, to make use of the thermal energy.

 

Not that I've let go of the saltwater idea completely... could a secondary container separate water whose salinity is increased by boiling from the less-salty water such that sea salt could be concentrated and stored? Do the materials this used in order to store molten salt hold a chance of being used on the inside surface of such a large container?

 

Pond water or lake water, at least if it was from unused areas, might be preferable to saltwater, but what about sewer water? Would the methane vapours produced be ignited by the heat, further helping to boil the water?