Carbon capture at moderate
pressures and temperatures
• Moderate pressures around 15 bar
• Moderate temperatures
– Hydrate formation at 2-6 oC
• Not far below cooling water temperatures in Nordic
countries
– CO2 release 20 – 40 oC
• Typical waste heat temperatures
Main concept overview
99% CO2
1% N2
Flue gas
15% CO2
85% N2
A closed process involving
cooling, heating, compression
and decompression stages to
form and melt CO2 hydrates
Hydrate promoter (formation pressure)
Seed particles (reaction kinetics)
Electric power
Cooling water
Waste heat
N2
Traces of CO2
The separation is possible
since CO2 forms hydrates
more easily than N2.
The problem with hydrate processes
• There is usually a long induction time before hydrate
production start
– Seed must form and grow to a certain size before detectable gas
absorption is observed
– This takes a long time – hours and days in pure systems
• The hydrate forms first where the gas concentration is
high
– Thus a droplet gets a hydrate crust around a wet inside
• This hinders the transport of gas into the water phase
• And heat away from the reaction centre
• Speeding up the process – the IFE contribution and a possible
breakthrough
– Using heterogeneous seed particle to speed up hydrate
formation – induction time reduced by a factor of 200
Comparing to chilled ammonia
process
• From literature chilled ammonia process
consumes energy in the range:
– 470 – 550 kWh/ton CO2
• A first rough estimate for a hydrate
process:
– 220 – 330 kW/ton CO2 (0.8 – 1.2 GJ)