NET Power, LLC

The Allam Cycle

The new power cycle - cheaper, cleaner and better.

Natural gas is burned with pure oxygen, not air, resulting in a combustion byproduct of predominantly CO₂ and water. Separating oxygen from air in an Air Separation Unit requires energy, but the high efficiency of the Allam cycle more than compensates for this requirement.

NET Power utilizes a single, more compact turbine that will produce all of the plant’s electrical output. Using a single turbine and eliminating all the other steam cycle components typical of combined cycle power plants enables the Allam cycle to reduce costs.

The CO₂ exhaust exiting the NET Power turbine also contains valuable heat energy. A heat exchanger is used to transfer this heat to a recycle stream that keeps the energy in the system (called recuperation). This process also cools the turbine exhaust for removal of the small amount of water in the exhaust stream.

The now pure CO₂ working fluid is pumped up to pressure and is passed through the other side of the heat exchanger. It uses the original turbine exhaust stream to reheat itself as it makes its way back to the combustor. Some of the CO₂ is removed and sent into a pipeline, where it can be used for enhanced oil recovery.

The heat in the turbine exhaust is recycled back to the combustor to keep the heat in the system, rather than lose it up cooling towers. This allows the Allam cycle to control the combustion temperature and to achieve extremely high efficiencies in a much simpler process.

Simple cycle.
Our cycle has low capital and operating costs due to its simplicity and its need for only a single turbine.

Oxyfuel combustion.
Oxycombustion burns fuel in pure oxygen instead of air, eliminating NO_x and other pollutants and generating a relatively pure stream of water and CO₂. The tight coupling of the air separation process to the rest of the cycle limits the parasitic load that has hampered oxycombustion in the past.

Zero air emissions.
Our cycle is a closed loop and therefore does not emit anything to the atmosphere. That means zero air emissions of carbon dioxide, particulate matter, SO₂, NO_x and CO.

Supercritical.
NET Power uses supercritical CO₂ as a working fluid instead of steam. This lets us avoid the efficiency losses that steam experiences when it transitions between a liquid and a vapor. Operating in the supercritical state has the additional benefit of producing a CO₂ byproduct that is at the pressure and quality that must be used in a pipeline. The energy and equipment that other power plants need to transform the CO₂ they produce into a pipeline-ready byproduct has made carbon capture uneconomic for them.

Zero water consumption.
Power plants are traditionally huge consumers of water. NET Power plants are able to avoid water consumption entirely by switching to air cooling, with only a slight reduction in efficiency.