Our technology

Circular Energy aims to build an offshore gas-fired power plant combined with offshore capture and storage of CO2.

Our innovative chain integration approach is built on three main components…

Offshore gas production

Our operational model holds several benefits compared to a traditional gas development scheme.

Producing the power in situ, offshore, makes it possible to split of the CO2 molecules which normally would be emitted after combustion, capture these and inject them back in the gas field. This activity constitutes a very efficient way of producing climate neutral electricity from natural gas resources. Our gas developments are fully independent of existing gas infrastructure as potential target fields no longer have to be located in reach of a gas pipeline but rather within reach of the offshore power grid, i.e. within a 70 km radius.

Offshore power generation

The Field Development Plan currently being drafted for Circular Energy’s upcoming project generates 185 MWe, tying into a major offshore windfarm. Given the probability distribution of wind speeds, we expect to be able to operate the equivalent of 75 percent of the time at full load. During the remainder of the time, wind speeds are such that the export cable is at capacity.

Current parameters for the next development opportunity include:

  • Average daily gas production 800,000 m3 (normal)/d (30 MMscf/d) from three wells
  • Power generation 1,200 GWh/yr using two Gas Turbines, two Heat Recovery Steam Generators, one Steam Turbine
  • CO2 captured 640 ktonne/yr using an post-combustion amine-based closed loop solvent.

Offshore capture and storage of CO2

CO2 in the dense phase is much less mobile than CO2 in the vapor phase. Because we inject from day one, we are able to maintain reservoir pressure near initial conditions, thus ensuring that CO2 remains in the dense phase throughout the lifetime of the project. As a result, there is a need to compress CO2 to around 200 bar (3,000 psi) at surface.

It is of course essential to ensure that re-circulation of CO2 through the reservoir is minimised. This is achieved by:

  • Well design allowing for isolation of certain zones over time
  • Well spacing allowing for perfect sweep efficiency
  • Pressures and temperatures that maintain CO2 in the dense phase

Additional benefits of Circular Energy’s integrated approach

No subsidence

The injection of CO2 into the same reservoir from which natural gas is being produced at the same time has a number of advantages:

  1. The same volume of CO2 is injected as the volume of natural gas produced, thus ensuring that storage capacity is sufficient over the lifetime of the project;

  2. There is no need for flowlines to a storage location elsewhere with considerable add-on investments involved;

  3. The pressure decline is much less than with classical depletion drive, preventing to a degree the movement of overburden and subsidence at surface.

 



Active on power markets

For countries like the Netherlands that are trending away from coal fired baseload plants and towards intermittent energy sources such as wind and solar, there is a corresponding increase in the need for peaking or load following power plants and the use of a grid intertie. Circular Energy answers to this market by operating a flexible load following power plant (short ramp-up, ramp-down cycle).  This facility only produces power during hours of Residual Demand (e.g. during low-wind conditions or  to cover sudden peaks in demand that occur at specific times). Combined with other flexibility solutions like demand-side respons (smart grids), energy storage and interconnection with adjacent markets this will provide the required system flexibility to support the growth in renewable energy.



Offshore system integration gas and wind

A great many EU programmes have recently been announced for offshore power generation from wind. This is growing our market as more and more gas fields come into reach. The power export infrastructure (transformer stations, cables, tie-in to onshore grid) is generally provided by the state, who also writes tenders for windfarm operators to build and operate the wind turbines.

With our flexible powerplant that easily switches on and off we can compensate the grid for the intermittence of wind. This is known as ‘load following’ and means in practice that we will be producing during low-wind conditions and shift down during high-wind conditions. This provides the much-needed flexible layer to energy markets with a growing share of renewables.