Dean Kamen Takes His Island Off-Grid | Hacker News Reader

Dean Kamen Takes His Island Off-Grid

spectrum.ieee.org

44 pointsmhb29 comments

Is Dean Kamen turning into a Bond villain, or what?

I'm hoping that he's turning into a Bond villian, considering the alternatives. He's been building terminator-style arms for a while now, out in the open, hiding in plain sight.

He does seem to be exhibiting many of the traits of Malign Hypercognition Disorder.

Even more interesting than this one-man band is the progress being made on Eigg and other remote islands off the West Coast of Scotland. Many have never been on the grid (they're islands with 10-100 people living on them) and they've previously relied on mucky diesel generators and such like.

Now, solar panels, wind turbines and hydroelectric are being installed to give these communities a stable energy supply.

http://islandsgoinggreen.org/

His "off-the-grid" system is really not very innovative (for an inventor that is). He should consider finding another means to store his reserves beside using a massive battery bank.

Some ideas:

1. Large Flywheel (on magnetic bearings, in vacuum)

2. Water Tower (pump sea water up to a tall tower, release at night)

That's what I thought while reading it. It seems more like his "Neverland" than anything actually groundbreaking. Just a buch of expensive geek toys on his island helecopter destination.

I think there's something to be said for actually walking the walk, however cushy it might be.

And to me, the most interesting part of his setup was the use of technology to balance sources of energy generation and consumption, and report on all of it. It's not just finding new ways to make energy, it's about using it more intelligently, which is a place where computers can help us make great strides.

I don't know about him, but it was my island and my home, I'd prefer a solution that worked. I'd save the tinkering for something other that the most important thing on the island.

> 2. Water Tower

I have though of doing this for my house in the past.

Before I start building the tower I wanted to have a feel for how much energy one can store using this method. I live next to the sea so water is no issue.

Say to power 1 low energy 20watt light bulb for a few hours how large would the tower have to be and how high from the ground.

I'd really appreciate a link to a resource explaining the maths behind this.

If it works the way I think it does, look up the (basic) physics around gravity.

You probably wouldn't even need to break out of the mass * g * height = energy equation.

Just (potential energy) * (efficiency)

I am going to assume 100% efficiency for simplicity. [1]

mgh Joule = 20 Watt * 4 hour * 3600 s/hour

(Joule = kg * m^2 / s^2 = W * s)

Lets say you pump water to a height of 10 meters.

m = 20 * 4 * 3600 / (9.8 * 10)

m = 2938.77 ~= 3000 kg

So you need about 3000 liters (1L = 1kg for pure water) of water at a 10m high tank to power a 20W bulb for 4 hours. This about 800 US gallons. Considering other inefficiencies, you'll need more.

[1] http://www.jcmiras.net/jcm/item/93/ (first google result for efficiency of a generator) says typical efficiency of a water generator is 0.95.

thanks that's very helpful indeed.

And compare that to the battery solution: 20W light at 12V: 1.7amps continuous 4 hours x 1.7A= 7 Amp-hours

That's about the capacity of a small 12V lead-acid battery that you can carry in one hand. Weighs about 4 lbs. I use one to provide LED lighting in my chicken coop because it's too far from the house to run AC power out there.

No contest: in the absence of extenuating factors, a cheap battery is better than the "innovative" (?) water storage method for such a small amount of energy.

In other words, you would need such a ridiculously large tower that the idea is not really viable. 3 tons of water for 80 watt hours? That's 37kg of water per watt hour. I use more like 4 kilowatt hours in a night; that's almost 150 tons! You're starting to talk about a serious, and seriously expensive, engineering project.

Maybe it would be viable if you lived next to a convenient cliff or other ready structure to simply place a big tank on top of with a pipe hanging down but if you actually have to build the structure yourself it sounds like a non starter. And that's without even considering the other engineering hassles you'd have, like corrosion, filtering seawater, maintenance, etc.

The reality is that battery systems have orders of magnitude more capacity per volume and weight. I'm probably going to get the math wrong, but the mechanical energy that a generator extracts from a gallon of gasoline (~ 11 kWh) is equivalent to the gravitational potential energy of 80,816,326 liters of water at 50 m. (8.08e7 = 3600 * 1.1e7 / 9.8 / 50). Without a lake on a hill, you aren't in the right ballpark. Flywheels are similarly useless for modern energy consumption.

With lithium ion batteries, the Tesla Roadster stores 53 kWh's in an area about the size of the trunk.

Modern Flywheels (in a vacuum with magnetic bearings) have close to the same energy density as batteries.

From Wikipedia:

"Flywheel power storage systems in current production (2001) have storage capacities comparable to batteries and faster discharge rates."

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

Also, I've heard that satellites often use flywheel's over batteries because they last longer.

Thats good to hear - most of the flywheel densities that I haven't been so high. I can't find any commercial wheels of that density for individual use, tho (many references to start-ups making them for central power utilities).

Satellites are a special case, as they have enormous budgets, plentiful solar power (so cycle lifetime is more important than capacity), and have the additional benefit of using the flywheels as a rotational propulsion device (usually in counter-spinning pairs).

It seems that commercial flywheels are about 7 times more expensive than batteries per kWh. The article mentions 24 batteries at ~$1,500 each providing "3 days" of power at an average of 2500 watts, so 180 kWh for $36,000. A recent blog post regarding Beacon Power flywheel systems quotes them at ~$1,400 per kWh, or ~$250,000 for 180 kWh.

http://neuralenergy.blogspot.com/2009/06/flywheel.html

> faster discharge rates

This phrase is the key to understanding why flywheels are seldom used. Read up on what happens if the wheel jams, cracks, or otherwise malfunctions.

I think "faster discharge" rates is being noted for their ability to dump large amounts of current very quickly. This is useful for large surges of power. It's not referring to some sort of parasitic leakage.

> dump large amounts of current very quickly

Consider what happens when the flywheel dumps all of its energy within a fraction of a second - a not-unlikely event in the case of almost any mechanical failure. Do I have to spell it out?

single page link: http://spectrum.ieee.org/energy/renewables/empire-off-the-gr...

It is a very interesting definition of "off the grid" which involves semi-regular shipments of semiconductors - an artifact of high civilization, notorious for its energy-intensive manufacturing process.

To me, the phrase "off the grid" does not necessarily imply living like a prehistoric savage - just something which one could reasonably hope to maintain if civilization collapses. LED lighting certainly doesn't fit the bill.

Dean Kamen is my hero. I'd love to work with him and his team. I'd probably be the dumbest one there and I'd love every minute of it.

Heating is not really an issue, because the island isn’t accessible on the coldest days, when the swell in the surrounding seas can reach 9 meters.

That probably makes his energy independence problem a lot easier of the coast of Connecticut.

After reading the first paragraph about having a lighthouse on the island and seeing the photo, I thought: "Ah, that must be what that ugly tower is in the middle of the island. Too bad he can't get rid of that."

Turns out it's his windmill.

It's really a shame that wind power has to look so ugly. I mean, those huge turbines they have in Spain are cool to look at, but even if you're a zillionaire with your own island, you can't get a house-sized windmill that looks like that. His looks like an ugly little cell tower.

There's gotta be a market there.

He's got a model of Stonehenge and it's not 18" high.

I first read the title as "Dean Kamen takes His island off-grid" and found it amusing.

huh?

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