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Ludi wrote:Trees used to work pretty well as a way to store the sun's heat.

Yes, they do. A bit slow though and they're stopped from doing all the other pleasant and wonderful things they do when turned back into heat.

Liquid salt storage systems, though problematic are wildly cheaper and probably good enough for heat storage if that's the route we want to take.

ian807 wrote:Liquid salt storage systems, though problematic are wildly cheaper and probably good enough for heat storage if that's the route we want to take.

Wildly cheaper than trees? (Which do all sorts of wonderful and pleasant things while they're growing)

Ludi wrote:Trees used to work pretty well as a way to store the sun's heat.

Before our population bloom made home-heating through logging unsustainable.

Trees don't work too well if you don't keep planting them.

Could be a sustainable resource.

Ludi wrote:Trees don't work too well if you don't keep planting them.
Could be a sustainable resource.

Could be, but there are just too many of us. Too much temptation to cut them all down to keep warm in the winter. Not such a problem here in Texas, but the folks in Idaho would be in a bit of a pickle.

Molten salt is a bit more re-usable and doesn't require deforestation. As a fan of trees. I'd prefer to use them mostly for nuts, fruit, shade, lovely, lovely oxygen production and CO2 removal, soil replenishment and such. Good climbing too.

Trees don't require deforestation, and can be grown many places. Many people can grow a tree, and build a little rocket stove to cook with. But most of us couldn't build a molten salt thingamadoo.

Not saying nobody should have molten salt thingamadoos, just saying trees are a technology that exists on a wide scale, can be scaled up or down, and can be implemented by many individuals or communities.

Ludi wrote:Trees don't require deforestation, and can be grown many places. Many people can grow a tree, and build a little rocket stove to cook with. But most of us couldn't build a molten salt thingamadoo.

Not saying nobody should have molten salt thingamadoos, just saying trees are a technology that exists on a wide scale, can be scaled up or down, and can be implemented by many individuals or communities.

I guess it depends on how many people there are and what sort of civilization you want. In the 1860s, there were enough trees for the population. Today at 300+ million folks, I'm not sure you could plant enough trees and crops for a sustainable, well-fed and unfrozen society, at least not one that uses much electricity. That said, I haven't done the math so I'm not certain of that.

I understand the hesitation regarding high tech, centralized, molten salt thingamadoos. I'd much rather have ubiquitous small and medium scale hydro, solar, wind, etc. to power the grid. For instance, I'm pretty sure that the Mississippi could be persuaded to crank out lots of power without bothering with dams using this fellow's design (http://www.alternative-energy-news.info/hydro-hydraulic-energy-invention/). The problem is, you have to store the energy somewhere for the winter and for that, molten salt is at least one good possibility. In fact, I can't think of anything much better that would work year 'round.

Trees keep getting in the way of my pickup.

I had a pickup truck like that once, I traced the problem to a loose nut behind the steering wheel.

On topic, a materials breakthrough in heat storage as outlined in the article would be fantastic.

On the other hand, salt storage is proven and ready to rip as Iam807 points out.

ian807 wrote:I understand the hesitation regarding high tech, centralized, molten salt thingamadoos.

I'm not so much "hesitant" as wanting folks to consider existing technologies that lots of folks can implement. I can't see any downside to folks planting lots of trees (except the truck problem, but that might be mitigated by employing smaller trucks). Personally, I would like to see folks investing in all kinds of technologies, preferably the least polluting and most sustainable, and preferably those which can be implemented on a personal, community, and regional scale, and which don't require a massive hierarchical infrastructure. Diversity is a survival strategy, so the more technologies, the merrier.

Ludi wrote:... I would like to see folks investing in all kinds of technologies, preferably the least polluting and most sustainable, and preferably those which can be implemented on a personal, community, and regional scale, and which don't require a massive hierarchical infrastructure. Diversity is a survival strategy, so the more technologies, the merrier.

I think we're violently agreeing.

Ludi wrote:Trees don't require deforestation, and can be grown many places. Many people can grow a tree, and build a little rocket stove to cook with. But most of us couldn't build a molten salt thingamadoo.

Not saying nobody should have molten salt thingamadoos, just saying trees are a technology that exists on a wide scale, can be scaled up or down, and can be implemented by many individuals or communities.

I will be building a rocket stove with thermal batteries (cob benches) for my new green house I'm building. I will take some pics, and if I can figure out how to post them, will put them up in the planning forum.

Ludi wrote:Trees used to work pretty well as a way to store the sun's heat.

I would have said "Yes, but you couldn't get a patent on trees and charge a royalty to grow and use them", but in reality various multinationals are always trying to do exactly that by patenting existing tree gene lines!

Proper management and proper species are all that are required for trees to work well.
I f you establish some cycle of rotation... what was called a woodlot from the middle ages till the 20th c in england.... you can manage the rate of use based on your population.

Secondly, as long as you don't require huge tree diameters for lumber, firewood can be used which is much smaller in size, and hence, younger.

A species like Paulownia Tormentosa can grow upwards of 8 feet a season in its first few years, and is ready for harvest for certain lumber applications within 5 years, and firewood in considerably less than that.

It is a bit slower growing outside its natural rage, but I have successfuly grown a row of them in Massachusetts.

The other great thing about them is they can be clipped a little up from the base, and will regrow from the rootstock just as quickly, with no re-planting required.

http://en.wikipedia.org/wiki/Paulownia

http://www.paulowniatrees.org/coppermine/displayimage.php?album=lastup&cat=0&pos=3

Here is a stupid idea that will never work.

Require everyone to have 10 acres of forest per person. Real forest. If a couple want to have a kid they need 30 acres between them, 10 for him, 10 for her, 10 for kid.

It would limit the population to a manageable size.

But, I think we are already way beyond that requirement.

Why 10 acres? No good reason, just seems like a reasonable number. We could base it on ag land, or on available renewable water just as well. But the thread is about storing the sun's heat and is talking about forests.

Okay, just did some calculations.

Lets say we take a 500 acre area, a zone which would contain 500 structures, no shops, and no institutions, and no food production in a typical sprawl pattern.

By applying proper low-energy-urbanism the 500 acre zone now supports 660 structures, with attendant shops, parks, farms, and institutions. A town.

The population has been doubled from 1,500 to 3,000

There are now 425 acres for growing to 75 acres of town.
Outside the inner 425 acre food ring (capable of sustaining 3400 people if biointensive practices are used) there are 3 rings of 208’ in width each

The first ring supports 84 acres of trees

The second ring supports 86 acres of trees

The third ring supports 92 acres of trees.

These rings acts as wood-lot energy producers for the town with a five year harvest cycle.



From the paulownia supply info. site the trees can be planted with a density of 132 per acre. Each tree produces 122 board feet of wood in a five year maturation period. 26 acres are harvested per year yielding:

132x122x42 bf per annum or 837,408 bf per year.

A cord of wood contains on average 500 bf so the production in cords per year is 1,675.

The 660 buildings each receive 2.5 cords of wood per year

Electrical generation by water jacket steam turbine generation have managed to achieve up to 70% efficiency.

“One cord of well-seasoned hardwood (weighing approximately two tons) burned in an airtight, draft-controlled wood stove with a 55-65% efficiency is equivalent to approximately 175 gallons of #2 fuel oil or 225 therms of natural gas consumed in normal furnaces having 65-75% efficiencies.”

So the equivalent in heating oil used for the demonstrated 1675 cords per year represents approximately 293,125 gallons per year or 444 gallons per structure per year

Reasonable amount if your climate isn’t too severe. Would work fine in New England.

You would have to plant more rings in more harsh areas. I would also say a factor of safety would have to be considered anyway, as these numbers are all taken off the internet and may not reflect what really happens.

But still, supporting the energy and food needs of a small town in the space taken up by a large subdivision isn’t that bad!

Sources:

http://www.zilkha.com/category/tree-facts/
http://www.iowadnr.gov/forestry/definitions.html
http://www.paulowniasupply.com/why_grow ... cially.htm

As long as you're not counting your woodlot as "forest" or "wilderness" ten acres per person might be enough. But you might need more than that to maintain watersheds, sequester sufficient carbon, etc so a good plan would be to have large areas of forest and wilderness which are not harvested. This is the plan of permaculture, one goal of which is to return the majority of land to wild nature, with human use areas being much more intensively maintained and productive than most ag land is now.

Talking about forests is definitely relevant to talking about storing the sun's heat, even though not relevant to the specific technology in the original post.

anador wrote:But still, supporting the energy and food needs of a small town in the space taken up by a large subdivision isn’t that bad!

Most of our town and suburban areas are badly planned and waste a lot of space that could be used to grow trees, including food trees. Not talking about New York City or other super-dense areas. Those are probably just not sustainable in the long run. In ye olden days, the largest cities were about 1 million people and were surrounded by farmland, not by suburbia.

Of course all these sorts of schemes require different land distribution, which is unlikely (though possible).

Village Homes is one of the famous examples of a development which incorporates trees, food growing, water catchment, alternative energy, etc. It isn't perfect and has had some problems, but it does exist as an example of how things can be done a little differently if we gave a rat's behind.

http://www.villagehomesdavis.org/

anador wrote:Reasonable amount if your climate isn’t too severe. Would work fine in New England.

You would have to plant more rings in more harsh areas.

Maybe not, had you build the houses with ground-coupled heat exchangers (http://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger). These aren't perfect solutions and don't work so well down here in Texas, but in the northeast, you'd use a lot less wood to heat your house if the air was pre-heated to ambient ground temperatures.

Farmers in central Pennsylvania near Penn's caves used to do something like this by building their farmhouses and barns over cave systems. Steady 65 degree temperatures year round.

This last year somebody here in Philadelphia wrote a book about living in Philly without air conditioning. He was on the radio as some kind of eco nut who was living on the edge, something most people would not do.

Well, we don't have AC and do quite fine thank you. We live in a 1887 house that was built before AC, high ceilings and double hung windows. Wife couldn't understand the double hungs and wanted to replace them for the first 10 years here. I finally got her to try opening them top and bottom to encourage some air flow and.......she get's it!!!!!!!!!!!! It works!!!!

My long winded point is that there is plenty of technology to make things better the failure mode is not our inability to think of things to do. It is our inability to DO them. The hard part is changing peoples minds. If you could do that, then....it would not be easy.....but you would have a shot. For me, I have pretty much given up on people and trying to some kind of rational action.

BTW, being a lucky guy, I have 168 acres of forest tucked away in Canada. My contribution to a carbon neutral planet. I still use too much fossil fuel and all that but I kinda figure in some way I am paying my way.