Saturday, March 29, 2008

ZENN moving forward

So, a bit more news about ZENN cars and through them, EEStor. EEStor, you'll recall, either has the silver bullet to make renewables competitive with all other forms of power, or they've got snake oil. Increasingly, it looks like the real deal. Certainly, ZENN seems to think it does. I've actually been interviewing some people at ZENN recently for a school thing, and I can tell you that the people there are long, long past the "does it work?" phase. ZENN expects to have a full-up highway-certified electric car by the fall of 2009.

So it looks like, shock of shocks, EEStor might actually exist. But how big a deal is this? Let's fiddle with some numbers here.

It really is very rare for any single wind turbine to be totally still for a 24 hour period. By "rare" we mean it has almost never happened in the operating histories of most European countries with significant wind power. If we assume that a 24-hour cycle is a reasonable unit of measure for a wind turbine, we can follow with some very conservative assumptions.

The first assumption is so conservative it's certainly wrong: that any electricity generated by a wind turbine needs to be stored before it can be sold. This clearly isn't the case, but I just got finished saying we need to design for resiliency, not efficiency, so I'll stick to that principle.

A 5MW wind turbine with a capacity factor of 30% will generate 40MWh over a day (on average.) To store 40 MWh of electricity, we would need 770 of EEStor's capacitors (from what we know of them from the patent filings.) Call it a round 800 -- again, conservative assumptions.

40MWh is enough electricity to provide 1.5 MW of power for more than 24 hours. In this sense, we've kind of designed a perverse system: using a perfectly good 5 MW wind turbine to generate a measly 1.5 MW. So what would it cost? Ah, the big mystery.

Well, not so much. The wind turbine itself would almost certainly cost around $5 million -- this has been the ballpark figure for wind for a while now. And how much would 800 of EEStor's capacitors cost? That's the big question. But we can make some guesses: for it to be useful to an automobile company, especially one that has stressed "affordability" as its goal, we probably want a capacitor that costs $10,000 or less. This means that the combined cost of the turbine and capacitors is about $13 million for a 1.5 MW system, or about $8.60 per watt of baseload power.

Which is only a bit more than what the people of Florida recently found themselves paying for a nuclear plant after -- surprise -- the price tripled on them.

Here's the thing: my above example of storing 100% of daily generation is really absurd. Even reducing that to 75% puts our hypothetical wind-baseload below nuclear power in cost. And if we go to a more reasonable 12 hours of storage, and the capacitors were to come in closer to $5,000 instead of $10,000 then the game's pretty much over -- renewables have won the day. Wind is competitive with coal, even for baseload, without a carbon tax -- which would still be a good, just, and necessary policy.

Something else that needs to be stressed: this would be a really stupid way to build a reliable wind-based system. Rather, what you would do is balance solar and wind against each other, with a much smaller fraction of storage -- preferably being built for you by eager electric-car buying consumers. If every car in Ontario had one of EEStor's capacitors in them, we'd have more than 24 hours of storage on hand -- most cars are parked 90% of the time.

But. I can't emphasize enough the hold that "baseload" power has on the minds of regulators and politicians, especially in Ontario. Mention renewables of any kind and "baseload" spits from their mouth like they're having a seizure. Of course, given that baseload is literally the only kind of electricity that nuclear can provide, this is a really cynical way of stacking the deck in favour of conventional sources without ever quite saying so.

So, "because there's no other options", it looks like we're about to pay more to build more nuclear plants because nobody is keeping their eyes open to the new technologies that are available.

(It's certainly worth pointing out that EEStor is only one of many energy storage companies out there, and there are plenty of other promising technologies too.)


adam said...

I dunno if it's still accurate, but their claims were $3,200 per 52kWh unit for the initial production, falling to about $2,100 with mass production.

That puts the cost of 770 units at $2.5 million at the inital price, or about $1.6 million at the mass production price. So with the $5 million for the wind turbine, that's a total of $7.5/$6.6 million.

mrjerry said...

yes Adam you got the math right

Anonymous said...

While supercapacitors can be used for storage of power as you describe for the wind turbines, they can also be used as buffers between peak and low demand periods.

Suppose that each household has one storage capacitor of say 10 kWh capacity. Then the peak power needs come from the capacitor rather than the grid. Power bought from the grid can be essentially constant. While this can be done with batteries the short life time low efficiency and long recharge cycles limits their usefulness. Now if there is a power outage in a community, every house with a capacitor can continue to operate at or near normal consumption levels. When the power is back on, charging must be metered to avoid overloading the grid.

In a car a capacitor could be charged at say 3kV on the road in just a few minutes. At home, charging would be at 120 or 240 volts overnight. High rate charging at home would be accomplished by hooking the car to a 3kV capacitor that has already been charged overnight. Just transfer the charge from one to the other. With the internal inverter the car can be slow charaged when at a motel or any location with 120 v power on hand.

Individual appliances of all kinds can use this concept. Already there is at least one electric tool (Coleman screwdriver) that is charged in 90 seconds. Virtually any tool now operated by a gas engine could be powered by a capacitor/motor combination that can deliver the high torque needed for power tool applications.

Keep a small supercapacitor in the car as a reserve against a low main battery.

I still have reservations about the safety of the device. It can contain considerable energy. If fully charged and then shorted (say, crushed) during an accident of some kind, there could be an explosion the equivalent of a tank of gasoline blowing up. Most gas tanks have special construction techniques to reduce this problem.

This is an invention of considerable importance and worthy of highest priority by industry and government.

BC Engineer