Cost Considera,ons for Direct Air Capture. Frank Zeman Assistant Professor, Chemical Engineering Royal Military College of Canada

Transcription

1 Cost Considera,ons for Direct Air Capture Assistant Professor, Chemical Engineering Royal Military College of Canada

2 Direct Air Capture!"#$%&'()*+#", '-#"&./%#+"+0%&'1*),. 20#)3+ >&?0#)3+ 50#'!"/+*#) 60%7".. 1*),'4.) C/CO 2 /CH 4 H 2 1*),':<&+=).0. 50#'!"/+*#) 60%7".. 1*),'4.)!8 9 '+% :+%#";) DAC closes the loop for distributed CO 2 emissions.

3 Conceptual Process Air E elec E elec E therm H 2 Contactor (CO 2 ) ab Regenerator CO 2 Fuel Synthesis (CO 2 ) f (CO 2 ) f E therm Fuel These 3 process steps will be required for any design.

4 The Na/Ca DAC Process Unit Processes: Air Contactor (packing & shell) Precipitator (produce CaCO 3 solids) Air Separa,on Unit (produce O 2 ) Lime Kiln (fired with O 2 ) Slaker (hydrate the lime) Compressors (CO 2 to 100 bar)

5 Energe,c Requirements* Electrical Energy kj/mol CO 2 % Absorber Fans Liquid Pumping Precipitator/Slaker Air Separa,on Unit CO 2 Compression sub- total 78.3 (0.49 MWh/t) Thermal Energy Precipitate Drying (10 wt%) CaCO 3 Hea,ng O 2 /CH 4 Hea,ng Flue Gas Cooling CaCO 3 Decomposi,on sub- total (6.1 GJ/t) Based on Table 2.4 in the American Physical Society Report Direct Air Capture of CO 2 with Chemicals April 28/2011. *Prior to considering 75% thermal efficiency.

6 Enthalpy of Reac,on? Report lists enthalpy of calcina,on at +198 kj/mol CO 2 separate from hea,ng and cooling (another 31 kj/mol) with the resultant produced at 75% efficiency. According to Thermodynamic Table (Handbook of Chemistry & Physics): (1) CaCO 3(s) CaO (s) + CO 2(g) ΔH r = 179 kj/mol, T=298 K Addi,onally: (2) CaCO 3(s) CaO (s) + CO 2(g) ΔH r = 165 kj/mol, T=1,173 K, where ΔG=0 Given that the report includes losses owing to inefficient heat transfer and CpT work separately, the calcina,on total (264 kj/mol) seems incorrect (62.5% eff). This has significant effects of the total energy inputs, fugi,ve emissions and overall cost of Air Capture.

7 Es,mated Costs - $653/t CO 2 Fugi,ve Emissions (Grey) $195 Contactor (Blue) $226 Fuel (Red) & Elec. (Yellow) $84 Regenerator (Green) $149

8 Correc,ons to Es,mate 1. David Keith claims the design would capture over 75%, not 50%, of the CO 2 passing through their towers. This would reduce bed height and pressure drop by 1/3. Affec,ng electrical energy for absorber fans and capital costs. 2. The ideal calcina,on energy is 165 kj/mol CO 2 or 3.75 GJ/t (a reduc,on of ~17%), not including O 2 savings. Fugi,ve Emissions $147 (26%) Contactor $184 (33%) Es,mated Cost $553/t CO 2 Fuel & Elec. $74 (13%) From: Carbon Engineering Comments on the APS report on Direct Air Capture David Keith, Geoff Holmes, 9 May 2011 Regenerator $149 (27%)

9 Op,mized* Design 1. Given the importance of fugi,ve emissions, on site genera,on may be advisable. A NG turbine burning 800 kj/mol fuel at 40% amounts to 495 kg CO 2 /MWh with 5.4 GJ/t CO 2 in the exhaust. This fuel costs of $53/MWh with 50% increase in NG consump,on. At 0.4 MWh/t CO 2, the residual heat is more than enough to dry the precipitate, saving fuel and O 2 with addi,onal savings in electricity and fugi,ve emissions. Fugi,ve Emissions $98 (19%) Contactor $184 (37%) Fuel & Elec. $71 (14%) Es,mated Cost $501/t CO 2 Regenerator $149 (30%)

10 Methanol Version 1. Eliminate compression to 100 bar, product is now CO 2 at 1 bar. 2. Change packing material from stainless steel (APS) to PVC (Keith; Zeman). Fugi,ve Emissions $50 (14%) Contactor $125 (35%) Fuel & Elec. $60 (17%) Regenerator $124 (34%) Es,mated Cost $360/t CO 2 1. David Keith claims a $50/t CO 2 contactor all inclusive ($285/t CO 2 total) 2. Consider wind at $180/MWh no CO 2 ($325/t CO 2 or $250/t CO 2 with CE contactor).

11 Cross Flow Contactor 1. Open system with poten,ally lower costs and pressure drop (50% of APS). 2. Two part structure, façade and packing, making one essen,ally fixed. 3. Based on commercially available packing materials (Brentwood XF12560) Images from Carbon Engineering (

12 Contactor Opera,onal Parameters Pump On Pump Off Pump On

13 Regenerator Cycles Long term heat goal is 200 kj/mol thermal load or $30/t CO 2 at $6/MMBtu.

14 Fuel Delivery Costs From Zeman F.S., Keith D.W. (2008), Carbon Neutral Hydrocarbons, Phil. Trans. R. Soc. A 366, , 2008 in special issue Macro Engineering Approaches for Escaping Dangerous Climate Change.

15 A Word on Biomass $!!!"#$%&'()* &'()*++!"#$%"&%1(2%!*3$42/%+,-$!560 #!! "!!,'-./*012-3!"#$% &'"'()*)+,#'-"./0"#()*)1#23/!! %! "!! "%! #!! #%! $!!!"#$%"&%'(")*##%+,-$"../0 From Zeman F.S., Keith D.W. (2008), Carbon Neutral Hydrocarbons, Phil. Trans. R. Soc. A 366, , 2008 in special issue Macro Engineering Approaches for Escaping Dangerous Climate Change.

16 Transi,oning to DAC CO 2 Removal Biomass Storage Solu,on Alkalinity Lime w CCS Direct Air Capture Carbon Neutral Fuels Fuel Produc,on Biomass FT H 2 CAR Fossil H 2 CAR Renewable Atmospheric Fuels Carbon Efficiency Fleet Modifica,on Raise Fleet Avg. MPG Flex Fuel Conversion Hybrid Designs Atmospheric Fuels

17 Concluding Thoughts S,ll more fundamental work on DAC. Although ~$30m spent in last 5 years should be a big year, with Carbon Engineering and Global Thermostat pilo,ng or completed pilot studies. Air Capture with CCS is inappropriate. Too much effort just to landfill. There is more than one way to get CO 2 from the air. Start with wastes. More than transporta,on, consider energy storage.