Using Shipping containers as compressed air 'Batteries

[FoggontheTyne]

so I've come to realize...all I want to know is what would happen to the circulation once it had started

 

[chetanladha]

There is a small prob here..
Renewable energy has anyways got a higher value of $/kW produced.
Top of that using this to compress air, store, and then expand again.. Each stage has got considerable amount of losses..
Overall the net power that u get won't justify the capital required to be put in..

 

[Unrest]

Top of that using this to compress air, store, and then expand again.. Each stage has got considerable amount of losses..
Overall the net power that u get won't justify the capital required to be put in..

As somebody else mentioned, large losses can be acceptable for storing renewable energy because the alternative - dumping it - has 100% loss.

Whether a particular way of storing it is cheap enough is a detail that can't be decided on simply by looking at efficiency. It depends strongly on how much overlap there is between the demand and production periods. It also depends on what other power sources are available to fill in the gaps. Having a lot of coal power and only a small amount of renewable will make storing renewable less economical. But the greater the proportion of power that's renewable (and cyclic), the greater the economy of storing it can be.

 

[carmatic]

arent there existing industrial devices based on pneumatic technology which has been proven to store compressed air very well? at the very least you can expect good reliability, if the efficiency has not really been a focus of these technologies

come to think of it, will a giant piston be more efficient than a pump/turbine combination?

 

[Unrest]

arent there existing industrial devices based on pneumatic technology which has been proven to store compressed air very well?

There are - air compressor reservoirs, but they're used when people want compressed air on demand. You don't want compressed air, you want electricity, so that opens up many more options.

Sure, compressed air would be technically feasible. But I think the biggest drawback would be the cost of the tanks. Calculate the energy density of an existing compressed air tank. See how many you'd need to power a city for half a day, assuming 100% efficiency.

If that shows it's impractical then there's no point trying to optimize the pump/turbine.

Turns out there's a wikipedia article onf Compressed air energy storage. It says you might as well use a battery.

 

[docfreezzzz]

This is a great idea! In fact, compressed air storage is already performed at several large utilities but only in a slightly different manner. Excess energy is used to compress air into salt domes buried deep in the Earth during off-peak hours. When extra power generation capacity is needed, the air is released through gas turbines (which don't need a compressor section since the air is already at a higher pressure) and natural gas is injected. After burning, the mixture is routed through a power turbine section and the system from there looks very much the same as a normal gas turbine.

I think the problem with shipping containers is mainly structural. Even just a few psi spread over the large steel walls could be enough to generate failure stresses in the material. As I'm sure most are aware, blocky structures are not ideal for compressed gas storage.

 

[chetanladha]

This is a great idea! In fact, compressed air storage is already performed at several large utilities but only in a slightly different manner. Excess energy is used to compress air into salt domes buried deep in the Earth during off-peak hours. When extra power generation capacity is needed, the air is released through gas turbines (which don't need a compressor section since the air is already at a higher pressure) and natural gas is injected. After burning, the mixture is routed through a power turbine section and the system from there looks very much the same as a normal gas turbine.

Is this the way excess power is managed in plants?
I don't know what do they do, but certainly this is not a very economic option..

 

[docfreezzzz]

I would have to disagree with you. The process is just compressing the air, which would normally be done in a gas turbine cycle anyway, a priori. There are some pumping losses involved with storage but the process itself is quite efficient. The required work is just done in discrete stages. Pumped water storage is also used quite heavily, as are high temperature metallic batteries. Another option which is used to avoid power spikes in large data centers is inertial storage (flywheels). These are normally used to avoid power loss while generators come online. Fact is, this is not a new problem but new technologies are always stretching our engineering knowledge.

 

[chetanladha]

I would have to disagree with you. The process is just compressing the air, which would normally be done in a gas turbine cycle anyway, a priori. There are some pumping losses involved with storage but the process itself is quite efficient. The required work is just done in discrete stages. Pumped water storage is also used quite heavily, as are high temperature metallic batteries. Another option which is used to avoid power spikes in large data centers is inertial storage (flywheels). These are normally used to avoid power loss while generators come online. Fact is, this is not a new problem but new technologies are always stretching our engineering knowledge.

Hi..
Yaa.. i'd a thought abt it.. Wat u r saying makes sense..
using a gas turbine cycle is a good option.
wats with the 'high temperature metallic batteries', how r they being used..