An Environmental Trifecta

Coupling Desalination with Carbon Mineralization to
eliminate CO2 and brine disposal, store energy, and
reduce salination of groundwater
John R. Hoaglund, III, Ph.D.
john@h2o-c.com (814) 574-2649
Carbon Negative Water Solutions, LLC
www.h2o-c.com

Overview
 Solutes from desalination “concentrate” (leftover salt)
are used as a substrate to capture CO2, SOx, and NOx.
 Brine discharge is eliminated. Instead …
 Brine and water resources produce commodities:
1. Minerals: “mined” from solution, inc. a de-icing agent
2. Gaseous: including hydrogen for energy storage
 Freshwater production is increased from:
1. the remaining solvent leftover from solute extraction
2. stack capture of the water from the combustion of the
hydrocarbon fuel (with water treatment onsite).
3. combustion or electrolytic oxidation of the hydrogen

How did Earth lower CO2 levels?
 CO2 in Archean atmosphere was at least 100 times higher!
[4% versus 0.04% today (versus .03% in 1980)]
 Photosynthetic blue-green algae raised O2 levels,
eventually oxidizing methane and excess Fe minerals,
enough to oxygenate atmosphere ~ 2.3 Ba …
 Algae consumed the CO2 … but that’s only part of the story.
 Photosynthesis = respiration + decay
 Reason why plant-based carbon offsets provide only
temporary carbon sequestration.
 Must bury the carbon.
 Geologic carbon deposits: Coal, oil, gases, carbonates

How did geologic carbon
deposits form?
 Coal: burial of coal forests (later in Earth history)
 Clathrate: microbial reduction of deep marine CO2
 Oil and related gas: burial of marine organic carbon,
including algae
 Carbonates associated with blue-green algae
(procaryotic cynanobacteria) removed the CO2 from
Earth's original atmosphere.
Stromatolites!

Photosynthesis associated carbonate sedimentation
Stromatolites--fossilized blue-green algal mats--in 2.1 Ga Kona Formation
dolomitic carbonates near Marquette,Michigan.

Natural carbonate formation:
 Acid is consumed (or base is added: H+ + OH- => H2O)
 Increasing pH increases total dissolved inorganic
carbon in solution:
 Increasing pH stabilizes bicarbonate (HCO3
-)and
carbonate (CO3
2-) in solution.
 Rising alkalinity splits between …
 hydroxide (OH-) base component
 bicarbonate (HCO3
-) and carbonate (CO3
2-) buffering
components.
H2O + CO2 <==> H2CO3 <==> H+ + HCO3
-
HCO3
- <==> H+ + CO3
2-

H2O + CO2 <==> H2CO3 <==> H+ + HCO3
-
HCO3
- <==> H+ + CO3
2-After Stumm and Morgan, 1981, Aquatic Chemistry
Changing
alkalinity
components in a
closed system of
constant Ct with
pH changing from
the addition of
base in a titration
OH-
HCO3
-
CO3
2-

What consumes acid in some natural systems?
Three examples:
1. Human respiration (a cycle)
 In cells: hemoglobin exchanges O2 for metabolic acid,
while metabolic CO2 goes into blood as HCO3
 In lungs: HCO3 neutralizes the acid into CO2 that is
exhaled, enabling hemoglobin to re-uptake oxygen.
H2O + CO2 <==> H2CO3 <==> H+ + HCO3
-
HCO3
- <==> H+ + CO3
2-

Three examples:
2. Chemical weathering: rocks are usually bases or
release bases when reacted with acid.
 Carbonate rocks: CaCO3 + 2H+ => Ca2+ + H2O +
 Hydrolysis of Feldspar to clay:
4KAISi3O8 + 4H+ + 2H20 → Al4Si4O10(OH)8+ 8SiO2 + 4K+
H2O + CO2 <==> H2CO3 <==> H+ + HCO3
-
HCO3
- <==> H+ + CO3
2-
CO2

Three examples
3. Ocean: photosynthesis uptakes acid as well as
carbon, phosphorous and nitrate in even proportions
 The Redfield ratio. (C : N : P : H) = (106 : 16 : 1 : 18 )
106CO2 + 16NO3
- + HPO4
2- + 122H2O + 18H+ 
C106H263O110N16P1 + 138O2
H2O + CO2 <==> H2CO3 <==> H+ + HCO3
-
HCO3
- <==> H+ + CO3
2-

Alkalinity components in an open system exposed to
constant atmospheric CO2 = 315 ppm
After Stumm and Morgan, 1981, Aquatic Chemistry

Alkalinity components in an open system exposed to
paleo constant atmospheric CO2 = 31,500 ppm (100x ! )

Can we mimic this industrially?

Yes, with brine electrolysis!

 2000: Moved to Penn State for coupled climatological
/ hydrological modeling. Al Gore is going to be in the
White House. Life is set.
 2002 Read The Hydrogen Economy by Jeremy Rifkin
 Hydrogen electrolyzed for trucks converted to run gas.
 2002 Attended Penn State Hydrogen Conference
 The new hot topic: hydrogen … and fuel cells
 ICE versus fuel cells: Q: “Why not just burn hydrogen
in an ICE?” A: NOx + heat waste
 I raised concern about freshwater demands.
Water Electrolysis
Hydrogen Production [2002]

Water Electrolysis
 90% of hydrogen is from the steam reforming of
natural gas.
Solves nothing: CH4 + 2H2O => CO2 + 4H2
 10% electrolytic hydrogen from fresh water
2H2O + e- => 2H2 + O2
 Requires freshwater. Resource competition?
“Freshwater exiting a fuel cell is from freshwater entering an
elecrolyzer.”
Hoaglund, J.R., C. Hochgraf, and T. Bohn, 2003. The hydrogen effluent. Ground Water
v 41, n 4. p. 404-405.
 Why? “Most efficient production uses a KOH solution.”

Compliments of a 2002 phone call with Hydrogenics
 Anode oxidation (“current into device” = electrons out)
2H2O + 4KOH ==> O2 + 4H+ + 4OH- + 4K+ + 4e-
==> O2 + 4H2O + 4K+ + 4e-
 Cathode reduction (electrons in):
4H2O + 4K+ + 4e- ==> 2H2 + 4OH- + 4K+
==>2H2 + 4KOH
 KOH is recycled.
Water Electrolysis

On to carbon sequestration …
EPRI interview question, 2006
 Interested in my background in the Michigan Basin for
CO2 sequestration in basin structures and brine
 CO2 is not only an asphyxiant, but at high
concentrations, a lethal gas
 “Would you be comfortable handling the public
relations aspects of an underground injection
proposal?”
 Carbon sequestration processes are industrial
processes (not necessarily environmentally friendly)

Going to California
Perchlorate work, 2007-2010
 2NaCl + 6H2O => NaClO4 + HOCl (oxidation half)
+ 5H2 + NaOH (reduction half)
 DOW Chemical’s earliest products from the
electrolysis of Michigan Basin brines in Midland, MI.
 DOW must assure NaOH product is air-tight to
prevent atmospheric contamination?
 Why?
NaOH (aq) + CO2 (g) ==> NaHCO3 (s)
baking soda

2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- => H2 (g) + Cl2 (g) + 2NaHCO3 (s)
1) Brine Electrolysis
2NaCl (aq) + 2H2O (aq) + e- => H2 (g) + Cl2 (g) + 2NaOH (aq)
Going to California
Putting it together, 2010
Salt: “An ionic compound that results from the neutralization of
an acid with a base.”
Electrolysis “undoes” the salt back into base NaOH … then
2) CO2 Aeration
2CO2 (g) + 2NaOH (aq) => 2NaHCO3 (s)

2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- => H2 (g) + Cl2 (g) + 2NaHCO3 (s)
1) Brine Electrolysis
2NaCl (aq) + 2H2O (aq) + e- => H2 (g) + Cl2 (g) + 2NaOH (aq)
2) CO2 Aeration
2CO2 (g) + 2NaOH (aq) => 2NaHCO3 (s)
Going to California
Putting it together, 2010
Was anybody doing this?
• J. Stolaroff: Use of NaOH sprays to stack capture CO2
• K. Lackner: Capturing atmospheric CO2 using NaOH

Going to California
AES power / Poseidon desal

 Original proposal to take 130 mega-gallons per day
(MGD) producing 65 MGD freshwater and returning
65 MGD brine at double seawater conc: 70,000 ppm
 On the books since 2002
 Variety of economic and environmental controversies.
 Approved by City of Huntington Beach, needs Orange
Co Water District (OCWD) customer, awaiting final
approval by CA Coastal Commission
 CA Coastal Commission requires GHG mitigation plan
 AB-32 regulates CO2 in excess of 25,000 metric tons/yr
Going to California

Two biggest environmental issues: brine discharge and
CO2
 Plan for brine: Ocean discharge of TDS.
 How much? ( Q )( r )( C ) = 17,655 metric tons / day
 Q = 65 MGD = 246,069 m3/day of brine
 r = 1025 kg/m3 solution density
 C = (70,000 parts / 1,000,000 parts) = 7% = twice seawater
 NaCl = 85% of ocean TDS = 15,009 metric tons / day
 Plan for CO2: Carbon offsetting by buying wetlands.
Going to California

Two biggest environmental issues: brine discharge and
CO2
 Plan for CO2: Carbon offsetting by buying wetlands.
 How much CO2 is Poseidon “indirectly emitting” ?
 Q = 65 MGD = 246,069 m3/day freshwater
 4 kWatt-hrs/m3 seawater desal by reverse osmosis (RO)
 0.55 kg CO2 per kWatt-hr (US EIA natural gas rate)
 541 metric tons/day liability (198 k/yr vs. reg’s 25 k/yr)
 AES total CO2 is 11,933 metric tons/day (541 is ~ 4.5%)
 904 MW plant produces 21,616,000 kWatt-hr /day
Going to California

2010 Eureka!
 2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- =>
H2 (g) + Cl2 (g) + 2NaHCO3 (s)
 Spoke with Carnegie Mellon physical chemist:
 DOW looked into this and didn’t pursue it. Not enough
market for chlorine products.
 Energy penalty is too high.
 “You’re talking about the Skyonic process.”
Use brine electrolysis with CO2 aeration to sequester
CO2, make H2, and eliminate brine discharge

2010: Carbon Negative
 2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- =>
H2 (g) + Cl2 (g) + 2NaHCO3 (s)
 Called Skyonic:
 Had just completed demo scale
 Won $28 million DOE grant for project scale.
 Currently capturing 75,000 metric tons off of cement
plant in San Antonio, Texas (Capitol Aggregates).
 Where do you get your salt? “We mix it.”
 !!!!!!!!!! Couple it with desalination !!!!!!!!!!

Budget: Salt
2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- =>
H2 (g) + Cl2 (g) + 2NaHCO3 (s)
 There’s enough salt
 NaCl salt and CO2 are mole for mole; 1.33 mass for mass
 AES plant CO2 total mass is 11,933 metric tons per day
 Poseidon NaCl mass is 15,009 metric tons per day
 CO2 equivalent mass is 11,301 metric tons per day
 A little bit short on needed NaCl mass, but …
 … other salts available in TDS of 17,655 metric tons per day

Budget: Water
2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- =>
H2 (g) + Cl2 (g) + 2NaHCO3 (s)
 You get more water!
 The other 65 MGD with solutes removed!!
 2.6 MGD from CH4 + 2O2 => CO2 + 2H2O
 AES plant CO2 total mass is 11,933 metric tons per day
 H2O / CO2 GMW equivalent ~0.41 metric tons
 2 for 1 moles yields 9,769 metric tons water per day
 Water treatment is onsite!
 Water from H2 oxidation relatively insignificant. Best to
use H2 to convert Cl2 to HCl?

Budget: The Energy Penalty
2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- =>
H2 (g) + Cl2 (g) + 2NaHCO3 (s)
 Step 1) Electrolysis is the energy intensive step
 2NaCl + 2H2O + e- => H2 + Cl2 + 2NaOH
 DG = +422.66 kJ/mol
 15,846 metric tons NaCl => 15,874 Mwatt-hr / day
 73% of plant output
 But that’s at STP. Higher temps, lower activation E
 Some energy back from H2 … and commodities
 Step 2) Aeration of CO2 releases heat energy
DG = -38.5 kJ/mol

Budget: Kinetics
2NaCl (aq) + 2H2O (aq) + 2CO2 (g) + e- =>
H2 (g) + Cl2 (g) + 2NaHCO3 (s)
 Step 1) Electrolysis is the rate limiting step
2NaCl + 2H2O + e- => H2 + Cl2 + 2NaOH
 Technology is scalable.
 Purpose of project scale application
 Step 2) Aeration of CO2 is fast
NaOH (aq) + CO2 (g) => NaHCO3

Algae biofuel carbon recycling
1. Algae: photosynthesis uptakes acid as well as
carbon, phosphorous and nitrate in even proportions
 The Redfield ratio. (C : N : P : H) = (106 : 16 : 1 : 18 )
106CO2 + 16NO3
- + HPO4
2- + 122H2O + 18H+ 
C106H263O110N16P1 + 138O2
2. Algae kinetics is too slow to keep up with stack
output
3. NaHCO3 is used to store / deliver CO2 for algae
 NaHCO3 + HCl  NaCl + H2O + CO2
4. Recycles salt: NaCl

Chlorine Sequestration?
 Demand? Skyonic claims to be able to produce a
desired proportion of chlorine products:
 Cl2, HCl, HOCl, NaOCl (bleach), ClOx
 Hydrochloric acid is the easiest to dispose of by
 Reacting with native metal: 6HCl + 2Al => 3H2 + 2AlCl3
 Dissolving serpentine rocks into magnesium chlorides.
 Magnesium chloride used in another carbon
sequestration method developed by Klaus Lackner
(now at ASU) to produce magnesium carbonates.
 Reactions of Cl2 with H2 returns chlorine to chloride
as HCl

A Lack of divalent cations …
Ca and Mg form more stable carbonates but are not in
sufficient enough quantity in seawater
1) Calera: combined CO2 and ocean salt to form CaPO4 cement.
2) Klaus Lackner’s solution for this:
 Serpentine Mg3(Si2O5)(OH)4 ore is used as the source for Mg cation.
 Process produces Mg(OH)2 reacted with CO2 to produce magnesite, MgCO3
 Requires serpentine ore dissolved by hydrochloric acid (HCl) to form MgCl2
 Reaction summary:
Mg3(Si2O5)(OH)4 + 6HCl ==> 3MgCl2 + 2SiO2 + 5H2O
3MgCl2 + 6H2O ==> 3Mg(OH)2 + 6HCl (brine electrolysis step)
3Mg(OH)2 + 3CO2 ==> 3MgCO3 + 3H2O (CO2 aeration step)
 HCl is recycled
 Therefore no salt consumption (no advantage for desalination)

Conclusions
 Solutes from desalination “concentrate” (leftover salt)
can be used as a substrate to capture CO2
 The process combines brine electrolysis with CO2
aeration to form carbonate minerals
 Can be combined with algae for biofuel C recycling
 Brine discharge is eliminated, producing products
 Freshwater production is increased from:
1. the remaining solvent leftover from solute extraction
2. stack capture of the water from the combustion of the
hydrocarbon fuel (with water treatment onsite).
3. combustion or electrolytic oxidation of the hydrogen

Conclusions
NaHCO3 to replace NaCl as a de-icing agent
NaCl  Na+ + Cl-
vs
NaHCO3  Na+ + HCO3
-
 Na+ reacts with soil minerals but Cl- is conserved. In
regions using road salt, Cl- levels increase at twice the
rate of Na+
 Instead, bicarbonate ( HCO3
- ) is beneficial, increasing
groundwater alkalinity

Conclusions
 Energy Penalty is high
 There are industrial hazards (as with any C-seq)
 Lack of market demand may require chlorine
sequestration
 Other techniques can create more stable carbonates,
but they recycle salt and /or use ores.
Desal: It’s not just for oceans
anymore!
There are related jobs for water
professionals

An Environmental Trifecta

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An Environmental Trifecta