

Biolite: Wood-burning backpacking stove also provides USB power - dctoedt
http://www.biolitestove.com/products/campstove/

======
zackmorris
Since it’s Sunday and I love guestimation:

To put this in perspective compared to the new 1.2 V, 3500 mAh NiMH batteries
(available for ~$1 each on eBay), let’s say we need 5 of them to go from 6 V
to 5 V as they discharge. That’s a total of 17500 mAh (17.5 Ah). 5 V at 4 W is
a current of 0.8 A by P = IV, so the batteries could run for just under
17.5/0.8 = 22 hours (slightly longer, since V > 5 which means I < 0.8).

They don’t say how much thermal wattage the stove puts out, but 1000 W
electric camp stoves are readily available so I will go with that. 2-4 W of
electric power translates to about 2-4% thermocouple efficiency which is
pretty good.

I think perhaps in the near future we’ll see some innovations in heat engines
like Stirlings which easily reach 50% of Carnot efficiency. They have a
reputation for low power to size ratios, but that’s due to lack of compression
(easily remedied if anyone, well, tried):

[https://www.youtube.com/watch?v=H_Vnxapd5fs](https://www.youtube.com/watch?v=H_Vnxapd5fs)

The Carnot formula is:

Carnot efficiency = (T high - T low)/(T high)

So to boil water at 212 F (100 C or 373 K) at an ambient temperature of 72 F
(22 C or 295 K):

Carnot efficiency = (373 - 295)/(373) ~= 21%

So a Stirling engine would achieve 10.5% at the heating surface, or about 2.6
times better than a thermocouple.

However, if we put the Stirling engine within the flame with modern ceramics
and, say, graphite lubricant which can go to 842 F (450 C or 723 K), we could
run at say 500 F (260 C or 533 K):

Carnot efficiency = (533 - 295)/(533) ~= 45%

So a Stirling engine would achieve 22.5% in the flame, or about 5.6 times
better than a thermocouple.

Of course then you are dealing with moving parts and it would probably be
unreliable. But the whole engine could be made airtight with the generator
enclosed inside, so it might be possible to build one with a service interval
of tens of thousands of hours or more.

Also I’m probably being too conservative on Stirling engine efficiency and too
optimistic about thermocouple efficiency, so a Stirling engine is probably
more like 5 to 10 times more efficient than a thermocouple.

I’ve often wondered if it’s possible to build a solid state device that raises
the frequency of infrared radiation to the visible range so that it could be
converted to electricity by a high efficiency photovoltaic cell. It can’t be
done by concentration alone because the laws of thermodynamics state that
concentrators can’t reach a temperature hotter than the source (5300 C for the
surface of the sun), although using multiple cells optimized for specific
frequency ranges seems promising:

[https://en.wikipedia.org/wiki/Concentrated_solar_power#Effic...](https://en.wikipedia.org/wiki/Concentrated_solar_power#Efficiency)

I see that as perhaps one of the great engineering challenges of our time,
because low temperature gradient free energy is all around us (orders of
magnitude more than we could ever use) but we have no way to gather and
concentrate it cheaply. So far this is the most promising method I’ve found
for visible light:

[https://en.wikipedia.org/wiki/Luminescent_solar_concentrator](https://en.wikipedia.org/wiki/Luminescent_solar_concentrator)

~~~
micro_cam
High compression sterling engines also tend to be really heavy and bulky since
the whole thing ends of needing to be encased in a compressed chamber. They
are cool though.

------
cstross
We've got one. My wife's used it on a weekend camping trip; I haven't had the
opportunity so far, so this is her second-hand report ...

It works as described. However, you need to charge the power module before the
first time you use it! The Biolite stove relies on fan assistance, so if
there's no juice the stove won't work.

Once it's working, it works fine and charges the power module (via the built-
in thermocouple).

The stove is designed to fold down and fit inside the optional kettle, so what
superficially looks like a bulky kit is rather less so in practice. However,
the stove+kettle combination weighs about 1.1Kg. There are lighter camp stoves
out there (until you start adding in gas cylinders).

The optional grill doesn't seem to fold down/store concentrically with
anything, so it adds bulk while costing rather more than rival cheap camping
grils.

~~~
sitkack
That sounds like a huge design flaw. It should have a hand crank to start
moving air over the TEC so it can create enough power to run the fan motor.

It seems kinda wrong to be out in nature, burning wood to charge a device. Why
is this better than a small solar panel? A panel wouldn't have the fire
danger, could be left out all day and charge its own batteries. Also, the
efficiency of a TEC is really low, lower than solar panels by a pretty large
margin.

~~~
mtabini
I reviewed one of these a couple years ago for Macworld, and ended up buying
one to take on my camping trips.

You don't actually need to charge the power unit in order to use the stove;
even if you start with a completely run-down battery, the unit will eventually
generate enough electricity to start the fan and achieve maximum efficiency.

Also, it's always seemed to me that the Biolite is designed primarily as a
reasonably efficient biomass stove—a role that, in my experience, it fulfills
really well, even with wet wood. I've cooked plenty of meals on it, and it's
much more convenient to carry around than a propane or white gas stove (as a
bonus, you also don't walk around with explosives in your backpack).

The ability to charge devices is a happy byproduct. It's handy when you're
cooking up some food and want to power up your phone or GPS receiver. It's
probably not as efficient as a solar charges but (a) a solar charger won't
cook food, so the Biolite is a convenient multitasker that requires less
backpack room, and (b) the solar charger doesn't work at night, when it's
cloudy, and so forth.

EDIT: FWIW, I also have a PowerPot, which is mentioned elsewhere in this
thread. It's pretty cool, and works well; it's also my preferred charging
method when I am not cooking, since I can just fill it with water and leave it
on the campfire for as long as I need (the Biolite, on the other hand, needs
constant feeding of fuel to continue running).

------
thekevan
This gets posted here and there every couple months. Each time someone talks
about how it charges things well enough but you do have to keep an eye on the
fire and feed it rather constantly, plus it's heavy.

However it seems that few people ever acknowledge that you basically have an
at-will generator that you can carry in a pocket--albeit as long as it's a big
pocket. So theoretically if you have this and a GPS unit, it's almost
impossible to get lost, no matter how long you are out in the wild.

It may seem a bit bulky and there are lighter and more efficient ways to cook
on the trail, but for the right sort of traveler, this stove is also bundled
with some potentially life saving abilities.

~~~
maxerickson
I'm not terribly adventurous in real life, but I think if you are planning on
getting that lost a GPS probably isn't the right sort of fallback (I'm
thinking a waterproof map and a good understanding of how to get un-lost in
the region you are in...).

~~~
drakeandrews
You ideally need both. A good GPS to tell you where you are, and a good map
(and the sense and skill to read it) to tell you how to get somewhere else.

My father once said a GPS is just a device to remind you how lost you are.

~~~
cuu508
In 2008 some friends and I went on adventurous trip through Russia and
Kazakhstan. Some of it was through steppe with rough roads/tracks/drivable
surfaces that are not on the maps. They were visible on satellite imagery
though.

Our navigation "solution" was a laptop and Garmin GPS attached via USB. Laptop
would be powered from car battery with power converter.

For software, we were going to use OziExplorer, which could display raster
maps, and show current GPS location on them. Ozi maps are simply big raster
images and there is limit of how big they can be.

Before the trip I found a tool that can scrape Google Maps satellite imagery
and generate Ozi-compatible maps. So I ran it on the parts of Russia and
Kazakhstan we expected to visit and got many gigabytes of cached satellite
imagery.

During the trip as we moved along, I would use the tool to generate Ozi map
for next area we were visiting. I got pretty handy at doing latitude and
longitude bounding box calculations "in head" :-) To give idea of working
conditions:

[http://i.imgur.com/0k7AEE5.jpg](http://i.imgur.com/0k7AEE5.jpg)
[http://i.imgur.com/X01vuNZ.jpg](http://i.imgur.com/X01vuNZ.jpg)

There were various "oh shit" moments along the trip, one of which was when the
power converter stopped working (and laptop's battery was empty because its
charging circuit got fried earlier, guess because of the unstable power or
overheating). GPS was still running on its internal battery so we did know our
latitude and longitude and bearing. But our paper maps were not much use. The
population density in steppe was so low, we could just drive until we'd run
out of gas and water, and not meet anybody. I think we were shorter on water,
as we had to use some of it to top up leaky radiators. Anyway, all ended well
when our mechanic-guy found and fixed a simple wiring issue with the power
converter, and we got the laptop back on!

So yes, you need GPS _and_ maps.

~~~
maxerickson
To be fair to the point I was making, you had used the GPS and maps to get
lost in the first place.

(Which is your group's choice to make; I don't mean to moralize and lecturify,
my earlier point was just to push back on the idea that a GPS and
thermoelectric stove are safety equipment)

------
fencepost
Probably the more significant thing is that it's a self-powered forced-air
rocket stove (part of the current generated drives a fan). The self-powering
is interesting, but I'm not sure how much it adds or if the forced air just
makes up for the energy taken out by the electronics.

The rated output (2-4W @ 5V) seems impressive, but I'm not certain I buy it or
at least I'd wonder just how much you need to be feeding the fire. I don't see
any mention of a battery pack, but I think if I'm charging expensive and
sensitive devices I'd rather charge batteries, then charge my devices with a
more stable current. Adding your own battery is going to bump the already-
considerable weight (> 2lbs).

They do present a comparison to the "conventional alternative" of an alcohol
stove + fuel + solar, but for some reason it seems designed to make the
conventional alternative as unappealing as possible (44 oz & > $200 for a
stove plus fuel for 2.5hrs of burn time!). Not included are options such as a
simpler rocket stove (easy to make) or a SuperCat alcohol stove (cheap &
REALLY easy to make) and options to make those more efficient (shrouds, etc.
sized for your cookware).

As for charging, there are actually some pretty impressive solar options
designed for backpacking - they aren't on-demand like this, but many of them
incorporate a battery system and could likely be used on a pack while hiking,
so the battery pack is available when you stop, and you can use them in places
where you don't really want a fire.

I'd have to call this fashionable, but I'm not sure how practical it really is
for most people.

Edit: forgot to mention, the base unit for this is ~$130, and the
kettle/carrying case adds another $50 and 1 lb to the whole thing.

------
SamWhited
I'm currently on the Appalachian Trail and have seen a few of these... They're
neat, but dont work very well. Maybe for a weekend trip. Not for serious
distance hikers.

~~~
mattgrice
For a few days, you can just bring a battery. They are much cheaper and more
convenient.

It is an interesting novelty, but it is just so heavy, bulky, and slow that I
am having trouble understanding who this would work for.

~~~
swalberg
I could see this being handy on larger group camps.

I'm a Scout leader and for a weekend camp will take a battery pack that will
keep all our leader's phones charged for the weekend, but if it were any
longer or wanted to give the neighbouring camps a charge, would need something
solar or fuelled. From what I've seen of the solar stuff out there, most can't
keep up with constant charging.

~~~
mattgrice
All the reviews I have seen seem to agree that it takes around 4 hours to for
the BioLite fully charge an iPhone. For the same amount of weight you could
carry 3 Anker 12,000 mAh batteries, which I believe would provide on the order
of 15 charges, at a cost of $150.

Unless you have scouts tending the BioLite constantly, I think it is
definitely not a solution for groups.

~~~
hrjet
But can the batteries cook your dinner?

~~~
mattgrice
Well, it only boils water. For that purpose some competitors would be: \-
Backcountry Boiler, which is also wood-fueled and 1/4 the weight. \- Jetboil
Sol, half the weight including fuel canister. canister good for 20+ boils \-
alcohol or esbit burner + titanium cup and fuel - less than 1/3 the weight
including fuel

The only scenario I can think of where the BioLite makes sense is if you have
no access to electricity for weeks at a time. Even then I think solar panels
make more sense.

------
K2h
This has looked cool, ever since I saw it announced, a peltier in a stove -
how awesome! i just can bring myself to pony up the cash as I fear it would
fall short of my expectations. kind of like this real world test.
[http://indefinitelywild.gizmodo.com/adventure-tested-
biolite...](http://indefinitelywild.gizmodo.com/adventure-tested-biolite-
campstove-review-1601840438)

~~~
nwh
Just to nitpick: it's using the seebeck effect not the peltier effect, they're
the reverse of one another.

~~~
K2h
good point, should have said TE or thermoelectric, i just learned of the
device as a peltier junction even though it has 3 different names depending on
the mode. at work we call it a TEC based on how we use it, but the best most
generic name is TE.

------
ChuckMcM
So there was a competitor to Biolite (PowerPot) on Shark Tank a couple of
months ago, they claimed a patent filed in 2010[1] on the technology, Biolite
filed in 2012 [2]

Grepping around the patent database doesn't turn up anything for the Powerpot,
or assigned to Power Practical, or invented by Dave Toledo so I'm at a loss to
know where they are on that.

That said, the tool, which requires boiling water only so that the correct
temperature differential is maintained, seems a bit too specialized for back
packing. It raises an interesting question on the weight budget for power
though. I am guessing that a white gas fuel cell would be a much better answer
from a practical point of view.

[1]
[https://www.youtube.com/watch?v=TZ5LAZJU2t0](https://www.youtube.com/watch?v=TZ5LAZJU2t0)

[2] [http://appft.uspto.gov/netacgi/nph-
Parser?Sect1=PTO2&Sect2=H...](http://appft.uspto.gov/netacgi/nph-
Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-
bool.html&r=2&f=G&l=50&co1=AND&d=PG01&s1=Biolite.AS.&OS=AN/Biolite&RS=AN/Biolite)

------
aiaf
Neat gizmo. But seems you have to be constantly worrying about the power
module:

\- Adjust the unit's placement so flames don't melt the power module \- Make
sure it doesn't overheat \- Re-charge it when not in constant use

Also I can see myself burning my hands trying to wiggle USB plugs in.

Could've used more work in the product design department.

------
anon4
Burning wood releases a lot of carcinogenic microparticles that enter your
blood directly from your lungs and is even worse for you than smoking. I'd
rather just carry some gas around and use solar power to charge my gadgets.

~~~
pudquick
You're not the intended market. The people likely to be buying this are those
who would have had a wood-based camping stove / sat around a campfire anyways.

------
DanBC
This youtube channel has some homemade tin can stoves. They are light and
efficient and would allow the camper space to carry alternative chargers.

[https://youtube.com/user/tetkoba](https://youtube.com/user/tetkoba)

I'm more interested in these designs.

~~~
maxerickson
Battery free wood burners seem to work well enough too:

[http://www.silverfire.us/scout-backpack-bug-out-
stove](http://www.silverfire.us/scout-backpack-bug-out-stove)

(No idea about that one in particular, just the first one I found when I went
looking)

------
gnicholas
Does anyone know how these compare to FlameStower? Their tech looks pretty
cool because you can use it with any heat source (campfire, camp stove, etc.),
but I don't know how the efficiency stacks up against these standalone
devices.

------
mmgutz
Green? Solar is much easier to charge your USB devices. I attach one to the
top of my backpack.

Seems pretty expensive for a wood burner.

~~~
joezydeco
I'd prefer a charger than can run overnight or in cloudy weather.

~~~
dublinben
You have to constantly feed this thing fuel in order to 'charge' anything.
It's an overpriced, overweight gimmick. You'd be better off bringing a stack
of extra batteries than this poor excuse for a stove/charger.

------
ams6110
Bringing phones on a camping trip seems to me like you're doing it wrong.

~~~
yzzxy
Clearly you don't go camping long enough/far enough away from civilization/in
dangerous enough areas to bear judgement on the practice as a whole.

~~~
DanBC
I get pretty awful phone reception when I'm on the number 10 bus travelling
between Cheltenham and Gloucester.

A phone _might_ provide some safety while camping - but it absolutely would
not be part of the safety planning.

~~~
yzzxy
While it's true that a non satellite phone is never a good panic button, in my
experience, [a] danger doesn't always correlate to distance from civilization.
[b] cell reception can be astoundingly good in the mountains, probably because
of clearer lines of sight.

------
JoeAltmaier
Cool, I'd buy one. But the 'green' argument doesn't hold water? Doesn't matter
what you burn; its all carbon.

~~~
JshWright
Plant a couple trees and over the next decade you'll sink more carbon than
you'll ever release with this thing (not considering the carbon emitted when
the thing was built and shipped to you...)

~~~
JoeAltmaier
Apples/oranges. Compare burning regular stove fuel vs sticks. Same btu - same
carbon footprint.

~~~
hollerith
When we get our fuel from trees, we've created space for new trees to grow. In
contrast, when our fuel is coal, gas or oil, eventually we run of of places to
plant trees (or we run out of the whatever is the scarcest nutrient for the
trees).

This is the basis for the claim that burning trees is friendlier to the
environment than burning fossil fuels is.

I am NOT pushing the claim, just pointing out that you have not yet
successfully refuted the claim.

~~~
dublinben
Most serious backpackers use alcohol stoves, which burn a renewable fuel
that's more efficient than wood.

~~~
sitkack
Most serious backpackers aren't concerned with nursing portable electronics
with a low efficiency TEC. People who actually need to use electronics in
remote locations bring a LiPo battery and a solar charger.

~~~
personZ
You seem really passionately against this.

This is a _camp stove_. You cook things on it. It has a fan to provide a very
efficient, very clean burn.

It _happens_ to have a charger on it as a side effect of being a fan driven
burner. I _guarantee_ that "getting power for free while cooking breakfast" is
dramatically more efficient than a solar panel.

Add that hiking I'm going to cook multiple times. Number of times I'm in open
sunlight, at a fixed location for a period of time -- approximately zero.

Not sure what you have against this, but it seems to be founded in the notion
that you think this is a wood-powered USB charger, when it's a camp stove that
also provides USB charging.

