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How compressed air energy storage in pipelines works

Breeze stores energy as compressed air inside a pipeline and delivers it through the same pipe. A compressor, driven by a gas engine today and by renewable power later, fills the pipeline with outside air. At the point of use the air spins a turbine and generator to make electricity, and the cold exhaust provides cooling.

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What compressed air energy storage in a pipeline is

Compressed air energy storage in a pipeline is a method of storing energy and moving it over distance as pressurized air. A compressor takes in outside air and pushes it into a pipeline. The compressor is turned by a natural gas engine at first and by a motor running on solar or wind power later. The pipeline is one continuous pressurized volume that is the store and the delivery route at once. It can be an idle steel oil or gas line covering a long distance, or new pipe laid in a trench for a community. The air stays in the pipeline until it is needed. At the point of use it is released through a turbine, which turns a generator to make electricity. No fuel is burned at that end. Air cools sharply as it expands, so the turbine exhaust is very cold and is used for cooling. Breeze Inc. designs these systems for community microgrids, pipeline energy networks and data center cooling.

The four stages

One pipeline with a compressor at one end and turbines at the other. The numbers on the drawing match the steps beneath it.

How the Breeze compressed-air system worksProcess diagram, not to scale. Outside air enters a compressor that is turned through a shaft and coupling by a natural gas engine today; at a later stage an electric motor run on solar or wind power takes the engine's place at the same coupling, and heat and water come off the compressed air at this end as a usable by-product. The compressed air is held in and carried by one continuous pipeline that runs from the compressor to the turbine, with off-ramps along the route where air can be taken off at an energy node. At the point of use the air expands through a turbine whose shaft turns a generator that makes the electricity, with no fuel burned at that end, and the turbine exhaust is cold air used for cooling.Outside air inNatural gasShaftGas enginedrives the compressor todaySolar or windMto the same couplingElectric motorreplaces the gas engine laterCouplingCompressorHeat and water offusable heat, a by-productPipelinestores the compressed air and carries itOff-rampenergy node on the routeShaftTurbineno fuel burned at this endGGeneratorElectricityat the point of useCold airturbine exhaust, used for cooling1234AirElectricityShaftLater stageFuelHeat and waterNot to scaleHow the Breeze compressed-air system worksProcess diagram, not to scale. Outside air enters a compressor that is turned through a shaft and coupling by a natural gas engine today; at a later stage an electric motor run on solar or wind power takes the engine's place at the same coupling, and heat and water come off the compressed air at this end as a usable by-product. The compressed air is held in and carried by one continuous pipeline that runs from the compressor to the turbine, with off-ramps along the route where air can be taken off at an energy node. At the point of use the air expands through a turbine whose shaft turns a generator that makes the electricity, with no fuel burned at that end, and the turbine exhaust is cold air used for cooling.Gas enginedrives the compressor todayNatural gasShaftSolar or windMto the same couplingElectric motorreplaces the gas engine laterCouplingCompressorOutside air inHeat and water offusable heat, a by-productPipelinestores the compressed airand carries itOff-rampenergy node on the routeShaftTurbineno fuel burned at this endCold airturbine exhaust,used for coolingGGeneratorElectricityat the point of use1234AirElectricityShaftLater stageFuelHeat and waterNot to scale

  1. Gas engines drive the compressors

    A natural gas engine turns the compressor shaft, and the compressor draws in outside air and squeezes it. The equipment is durable, available and familiar to oil and gas operators. Compression gives off heat, which is available at the compressor site as a by-product.

  2. The pipeline stores the air and carries it

    The compressed air is pushed into a pipeline, existing or new. It can be stored indefinitely and delivered on demand without energy loss. The same pipe carries it to the point of use, and air can be taken off at points along the route. Compressing and releasing can happen at the same time.

  3. Turbines turn generators, and the exhaust is cold air

    At the point of use the air is released through a micro-turbine. The expanding air spins the turbine, the turbine turns a generator and the generator makes electricity. Nothing is burned here. The exhaust leaves very cold and is used for cooling.

  4. Renewable-powered motors replace the gas engines

    As solar or wind is added, a renewable-powered electric drive takes over from the gas engine at the compressor. The pipeline and the turbines are unchanged, so nothing downstream is rebuilt.

What comes out of the system

Two products at the point of use and one by-product at the compressor.

Electricity

A generator on the turbine shaft makes electricity where it is needed: at a turbine hut serving a group of homes, at a node along a pipeline or at a data center.

Cold air

The turbine exhaust is very cold. In a community it serves a freezer and cools buildings through standard ductwork or radiant coils. For a data center it arrives below zero and is warmed to about 22°C before it enters standard ventilation.

Heat at the compressor

Compressing air heats it and wrings water out of it. Both are available at the compressor site, and Breeze proposes sending them to nearby greenhouses.

System figures

Storage duration Indefinite, without energy loss
Storage capacity 200 meters of 34-inch pipeline can store 675 megawatt hours
Supply air to a data hall About 22°C, after warming
Community microgrid 150 to 200 homes
Pipe pressure rating About 150 psi, plastic pipe in the New Mexico pilot
Turbine exhaust temperature Below zero

Start with gas, transition to clean

Drive today Natural gas engine
Drive later Motor on solar or wind power
Unchanged Pipeline, turbines, generators

Why start with natural gas?

Starting with natural gas lets a system be built and put to work now, before solar or wind is in place. Gas engines and compressors are durable, available and already familiar to oil and gas operators.

Fuel is used at the compressor end only. Nothing is burned at the turbines, wherever along the pipeline they sit.

How does the switch to renewables happen?

The switch happens at the compressor and nowhere else. As solar or wind is added, a renewable-powered electric drive replaces the gas engine.

The pipeline, the turbines and the generators stay as they are, so the system does not have to be rebuilt. The air in the pipe is the same whichever drive compressed it.

Steel pipes and ducts running up the outside of an industrial building

Common questions about the technology

How is this different from batteries or cavern compressed air storage?

A battery stores electricity in one place and gives back electricity. Breeze stores energy as compressed air in a pipeline that also carries it to where it is used, and the same air yields cold air for cooling as well as electricity.

The store is the pipe itself, which can be an oil or gas line that is already in the ground, and air can be taken off at several points along it.

Compared with compressed air stored in a cavern, the store here is a pipeline, so it is also the delivery route, and nothing is burned at the turbine. Other compressed air storage fills an underground salt mine; a pipeline lets the air be moved as well as stored.

How long can the air be stored?

Indefinitely. The air can be stored indefinitely and delivered on demand without energy loss.

How much a pipeline holds depends on its size: 200 meters of 34-inch pipeline can store 675 megawatt hours.

What happens to the heat from compression?

The heat comes off at the compressor and is available there as a by-product. Compressing air heats it and wrings water out of it, and Breeze proposes sending both to nearby greenhouses.

Can the system store and deliver at the same time?

Yes. Compressing and releasing can happen at the same time, so a pipeline can be filled at one end while air is drawn off at another.

Is any fuel burned at the turbine?

No. The turbine is driven only by the expanding air. Fuel is used at the compressor end, and only until renewable power takes over there.

Where can air be taken off a pipeline?

Air can be taken off at points along the route, and each one becomes an energy node. A node can serve EV charging, a manufacturing plant, an edge data center, a village, greenhouses or hydrogen production.

The system in four short videos

Each explainer runs about a minute and comes with a written summary of what it shows.

Energy storage in pipelines

25% of the 3 million miles of oil and gas pipelines in the US are idle. An idle line is filled with compressed air, and 200 meters of 34-inch pipeline can store 675 megawatt hours. Air is compressed and released at the same time, and off-ramps along the route supply EV charging, a manufacturing plant, an edge data center, a village, greenhouses and hydrogen production.

A community grid

New poly pipe is laid in a trench through a community, alongside communication wires. Turbine huts, shared or one per building, make electricity, and the cold exhaust serves a freezer and building cooling. Heat and water from the compressor go to nearby greenhouses.

Data center cooling

A data center at the end of a pipeline takes both products of the turbine. The exhaust air arrives below zero and is warmed to about 22°C before it enters standard ventilation, or it chills the water that feeds the chillers.

An independent grid

The whole system in outline, as a grid that runs on its own compressed air supply: energy without interconnection delays. Start with natural gas at the compressor and move to solar.

Three ways the system is used

Community microgrids

Powerhood supplies electricity and cooling to microgrids of 150 to 200 homes, and can be installed before the homes are built.

About Powerhood microgrids

Pipeline energy storage

CAPS, Compressed Air Pipeline Systems, turns stranded oil and gas pipelines into long-distance energy delivery networks.

About CAPS pipeline storage

Data center cooling

Ultra-cold air, supplied on site or by pipeline, cools a data hall through its standard ventilation system.

About data center cooling

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