NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
Power-to-Gas Biomethanation: A Unique and Sustainable Approach
to Renewable Natural Gas and other products
Kevin Harrison & Nancy Dowe National Renewable Energy Laboratory AGA/EPA 2019 Renewable Natural Gas Workshop
Peppermill Reno – Reno, NV
September 24, 2019
Me,an LCOE $/MWh
$3,60 359
330
300
270
240
2 10
180
150
S135 1.20 23
$11 90
83
60
Advanced e,ner,gy techn1ologaes are :providi'ng re,al-wo1rld s,olutions by:
• Becoming increasingly cost-competitive
., Boosting the US. energy ·ndustry
• Provid ing jobs ~or American workers
102 Coal (8%)
O , ...... _. o 1n d C cl { 27)
50 Utill Scale olar (86 ) 30 .___ _____________________________________ _ $ 5 Wind (67 o)
2009 2010 2011 2012 2013 2014 2015, 2'016 20 7
Source: lmard's lOl 7 L v llzed Co r of En rgy Analysis, V r ion L 2 No m 20 7 Rt I 6 https://www.lazard.com/perspective/levelized-cost-of-energy-2017/
Recent U.S. Electricity ''New ,Capacity''
Far from {{alternative,, , ren,ewable en,ergy and natural gas is the new
normal in the United States
New U.S. Electricity Generating Capacity Additions, 2010-2018
100%
90% ....... :,:g ., - 80% 00 c:: 0 E 70% ,:, 'Cl <( >, 60% -~ 32% ro C. 50% ro u ~ 40%
;a: 0 30% ~ ro .c 20% (J)
10%
0% 2010 2011 2012 2013 2014 2015 2016 2017 2016
■ Solar ■ Natural Gas ■ Coal ■ Wind Othar
Source. Wood Macken~e Power & Renewables FERC (All o her tec:hnolog1osl
Wind
NG
Solar
J:
~ t.:)
Figure 4. Total Renewable Generation Serving California Load by Resource Type
100 000
90,000 BTM Solar
Solar 80,000 Wind
70,000 ■ Geothermal
Small Hydro
60,000 Biomass
50,000 '!let.id M
40,000
30,000
20,000
10,000
0 I
1983 2002 2006
Ff5l Ca lfCf ,a RPS e bliYled RPS mcreased to ZO% by 2010 (?OO(i by 20m CSI Initiated Global warm11g
Sokltlons Acl of n Source: Ca lifornia Energy Commission, staff analysis November 2018
I I I 20 1
RPS aeased to 33% by 2020
2015 RPS increased
lo 50% by 2030
Estlm te
14%
31%
29%
1
4%
%
2018 RPS1ooe.1~ to 60% b'{ 2030
BTM Solar 13, 18
Solar 30,262
Wind 27,838
Geothermal 3,249
Small Hyd o 4,347
Biomass 8,04
The Need for Long-Duration Energy Storage
Conventiona l Storage
Electric Grid Infra structure
Hydrogen
~Vehicle
~
End Use
Upgrad ing Oil /
Biomass
Ammonia/ Fertil izer
H2@Scale Initiative
2.5M miles
Benefits of Renewable H2 • Enables higher
penetration of renewable electricity
• Electrolyzer can provide grid services
• H2 provides flexibility
• O2 is a byproduct, too
• Growing transportation sector •
•Reduces fossil fuel consumption Scale-able, non-toxic, low temperature process
10 MM tons H2 /year in U.S. https://www.energy.gov/eere/fuelcells/h2scale
] ______________________________________________ ----------l!i!lir
100□ I
·---------------------------------------------~-1 Ma11th
100 ...,
~--------------------------1Day
1 .,- - - -_____________ _,_
E-101.:ir
o.:m.
O.ol
0.001 --+-1 kWll 10 klMI 100 kWh Ml.Wh 10 MWh 100 MWil 1 <rWh 10 GWl!J 100 r.ffl ~ 1 T\1'1,111 lOTWh 1 TW'h
Storing Renewable Electricity as Molecules
Electricity, transportation, feedstock and heat • NG has high energy density ~7x greater than H2 • Existing national energy transmission system • Flexibility in energy use • Shifting RE with seasonal energy storage • High scalability of P2G and RNG Production
Over 130 billion cubic feet of natural gas
storage capacity exists in Southern California.
To put this in perspective, this is
enough to supply all of the gas-fired generation in the region for more
than two months.
- SoCalGas
Wind and Solar Curtailment Totals 800,000
250,000
225,000
200,000
~ 175,000 .c ~ e., 150,000 ... ::,
_g 125,000
1 ro 100,000 O'l Q)
~ 75,000
Wind and solar curtailment totals by month
California ISO
:::: 111 1 I II .. 111 11 I I I I I I I I I Jan '17 Jul '17 Jan '18 Jul '18 Jan '19 Jul '19
700,000 714,445
600,000 Thru August
500,000 461,054 400,000
401,493
300,000 308,421
200,000 187,722
100,000
-2015 2016 2017 2018 2019
http://www.caiso.com/informed/Pages/ManagingOversupply.aspx
MW
h Cu
rtai
led
Solar and wind curtailed by year
Production only assume: 50 kWh/kg H2
Thru August of 2019 alone, over 76,000 Metric Tons of CO2 could have been recycled!
Year MWh MT kg H2 MT CO2
2015 187,722 3,754 19,992
2016 308,421 6,168 32,846
2017 401,493 8,030 42,757
2018 461,054 9,221 49,100
2019 714,445 14,289 76,085
(...__]
Waste-to-Energy: Biogas Sources of CO2
Solar Energy
Other Low-Carbon
Water
Renewable CH4
BIOMETHANATION REACTOR
CO2 + 4H2 → CH4 + 2H2O
e -
H2
CO2 (~40%) CH4 (~60%) Nutrient
Supply
NG Storage Network
End Uses: Heat, fuel, chemical feedstock
Electrolysis O2Biogas Sources
Wastewater Fermentation
Landfill Energy Crops
Manure
Wind Energy
Biogas Supply
Re-electrification via fuel cells or gas-fired power plants
Heat
Meets SoCalGas’ Rule 30 gas
quality standard
HHV R30: 970-1150 CO2 R30: 3% max H2 R30: 0.1% Trigger* *SoCalGas doe nothave a shut-offlimit, but this leveltriggers additionalstudy/testing.
Renewable Hydrogen Production Step 1: Using renewable electricity to split water into hydrogen and oxygen in an electrolyzer
½” dia. H2 tube at 400 psig
Rules of Thumb • MW-scale: 50 – 55 kWh make 1 kg of H2• 1 MWe electrolyzer, ~400 kg /day 2H2O + e- 2H2 + O2 + Heat • 1 kg H2 ~1 gallon of gasoline (gge)
_44
! 42 -~ 40
~ 38 Q.
u 36 <C
:U 34 N
f 32 ... t 30 cu -LLI 0 10
- PJM RegD Command
- Electrolyzer AC Power
20 Time (min)
30 40
Electrolyzer – Electricity Grid Support
1 Sample per second
Electrolyzer systems are flexible electrical loads that
can help stabilize the electrical grid and enable
higher penetrations of renewable electricity.
Supporting grid stability • Typical utility profile to validate performance• System response, not just stack• 120 kW PEM stack operating on NREL’s electrolyzer
stack test bed• Flexible demand side management tool could be
used to provide frequency response service
Source: Harrison K., Mann M., Terlip D., and Peters M., NREL/FS-5600-54658
Biomethanation – RNG Production from CO2Step 2: Using the renewable H2 (from Step 1) and CO2 in a downstream biomethanation process to produce renewable methane and water
Biocatalyst 4H2 + CO2 CH4 + 2H2O + Heat
Benefits of Biomethanation • Recycles CO2 …. As well as the CH4
o Ethanol, dairies, wastewater, breweries, fossil• Meets (SoCalGas’) pipeline quality standards
o 998 BTU/CF, 0.89% CO2, 0.4% H2
• Scale-able, non-toxic, self-replicating biocatalyst,• Low temperature (65°C) systems
Rule of Thumb: 10MWe of electrolysis feeding a bioreactor can produce ~500 scfm (12,000 Nm3
or 440 MMBTU per day/6 g/L-hr) of methane and recycles ~20 tons of CO2 per day
H2 & RNG Systems at NREL Electrolyzer System H2 and RNG R&D Site Today, 250 kW PEM stack
5 kg H2 / hr 30 bar H2 Pressure
Up to 70 bar max (4) Power Supplies
Current-sharing mode 4000 Adc at 250 Vdc
#1) 350 and 700 bar pre-cooled H2 dispensing system #2) Diaphragm and piston compressors #3) 700 L bioreactor – operates at 18 bar (260 psig) and 60 - 65oC with agitation, recirculation loop and cell recycle #4) 200, 400 & 900 bar storage - 350 kg Total
#3
#1 #2 #4
J i
A1•--~ ~ .__. fttJ.8'1 ••• , f 7 2
Cd f
L ■ C a•n-
/
Varying Input Gas Flows Ga
s Flow
Rate
(kg/
hr)
7
Step-up and step-down response 6
shown 5
4 Bioreactor can load follow like an Carbon Dioxide
3 electrolyzer 2
Challenge: Low density gas, like H2,Hydrogen 1
is difficult to monitor 0 2:52:48 PM 3:07:12 PM 3:21:36 PM 3:36:00 PM 3:50:24 PM
Time
7 Goal: Maintain > 98% methane
production under varying input gas flows
Gas F
low
Rat
e (k
g/hr
)
6 5 4 Carbon Dioxide 3
Trace CO2, H2 and H2S remaining
Maintain H:C Ratio 2
Hydrogen 1 0
Ideally 4:1 H2 to CO2 3:47:31 PM 3:54:43 PM 4:01:55 PM 4:09:07 PM 4:16:19 PM 4:23:31 PM 4:30:43 PM
Time
\ 100
SoCalGas – 700L Bioreactor Start-up Pe
rcen
tage
(%)
90 Increased
80 Agitation
70 Started new Day at lower
60 Increased agitation
Agitation 50
40
30
Low Agitation 0.6 kg/hr H2
3.0 kg/hr CO2
Methane CO2
20
10 Day 4 Day 1 Day 2
Day 3 0 5 10 15 20 Hours of Operation
After 24 hours of total operation conversion
reached 92%
During this start-up phase the biocatalyst grew to 10x the initial population
Agitation reached 50% of maximum RPM
Flow rates 20% of rated
Reactor pressure 4 bar during this time
18 bar (260 psig) max.
25 0
-0-
-0-
,_____,A~-...... r ,
Increasing Pressure to Improve Conversion
0
10
20
30
40
50
60
70
80
90
100
Perc
enta
ge (
%)
Hours of Operation
% Conversion Conversion reached
98%
Conversion = % CH4 % CH4 + %CO2
Operational State Start pressure 5 bar
Returned to lowagitation rate
0.6 kg/hr H2
3.0 kg/hr CO2
28 30 32 34 36 38 40
Methane CO2
Increased Pressure to 7 Bar Increased
Agitation 50%
Increased Pressure to 6 Bar
ectrochaea
Biocatalyst – Methanogenic Archaea Growth Requirements
• Seawater environment• Salts and minerals• 60 ‒ 65oC• Anaerobic conditions• Feedgas: CO2 and H2
Long Term Stability
• Capable of daily startup• “Load” following• Robust• Self-replicating• Fast recovery during
start/stop cycles
Electrochaea’s proprietary biocatalyst is a selectively evolved – not genetically
modified – strain of methanogenic archaea, aMethanothermobacter thermautotrophicus single-celled microorganism that has populated Earth for Efficient 98.6% of carbon goes into methane billions of years
Productive VVD* of 800, H2 mass-transfer limited http://www.electrochaea.com/
Quick return to methane production within technology/Responsive seconds/minutes
Selective 100% methane, no intermediates
Robust Tolerant to oxygen, H2S, CO, Sulfate, Ammonia, particulates
Simple Moderate temperature range (60 ‒ 65°C)
4.5 r;:== 4.20
·-u4· _0•, R&D Advances ■ Other Costs
.::.:: -
........ ,41').
·~ 3,5, 1Q
t; 3.0 = 't:I e 2.s 0. t: m 2' 0 tit) ,, --'
1p I.,
"D 1.S > ~ ::c c 1.0 .., ,v, 1g o.s u
0.0 Ca!P•acirty Factor
Cost ,of E 1ectriicity Capita1I Cost
Effi de ncy ( LHV)
■ Feedistoc:k Costs
■ F11xed O&M t--, 2.77
■ Capita I Costs
3.46 1.05
1.16 -----. 1.56 0.58
'97% 40% 40% 1--------+---:--~-~-:--~""."'."""1 ¢6. 6/kWh ¢2/kWh I ¢1/kWh ¢2/kWh I 1¢1/lkWh $400/kW $400/kW $ 100/kW
·66% 66% 60%
Steam !Methane Reforming
Challenge – Reducing the Cost of H2
CURB SIDE VIEW
Upcoming Projects
DOE Bioenergy Technology Office, SoCalGasand Electrochaea Biopower: Upgrade biogas to pipeline
quality RNG
Design and build a scaled-down mobilebioreactor
Analytical development
SoCalGas, Bioenergy and Fuel Cell Technology Offices H2@Scale: Systems integration and optimization IP development Gas mixing and mass transfer
Biomethanation – Bulk Energy Storage and… • Recycles CO2 in addition to the CH4
• Sector Coupling – Electrons-to-Molecules
• Biogas and pure CO2 are potential sources
• Uses the existing NG network (2.5 Million miles)
• Produces a “Drop-in” replacement for fossil NG
• Heat and oxygen are (also) produced in this two-stepprocess
• Enables higher penetrations of solar- and wind-generated electricity
Meets SoCalGas’ Rule 30 gas quality standard
Higher Heating Value: R30: 970-1150 • Shifts, in time and space, the BTU/CF Carbon Dioxide: 3% max. production of renewable electricity Hydrogen: R30 - 0.1% Trigger for more
testing and study, SoCalGas does not have a shut off limit set.
Southern California Gas Company
). A ~ Sempra Energy utility"
Electroc a U.S . DEP.AIRTMENT OF
ENERGY Energy Eff ciency & Renewable Ener,gy
Partners
Bioenergy
H2 & Fuel Cells
Solar Energy Doris Hafenbradl, CTO
Mich Hein, CEO Ron Kent
Pictures taken on August 13, 2019 at NREL’s 3rd Partnership Forum during the SoCalGas bioreactor dedication ceremony
Contact Information
Kevin Harrison Senior Engineer National Renewable Energy Laboratory (303) [email protected]
Nancy Dowe Senior Scientist - Microbiology National Renewable Energy Laboratory (720) [email protected]
B1i0Cat Project 'o I
Tronsform;ng EN RGY
MsoCalGas A ~ Sempra nergy utilitl
System Comparison
P2G - BioCat P2G - SoCalGas
Location Copenhagen, DK NREL - Golden, CO
Volume 3,500 L 700 L
Electrolyzer 1 MW – Alkaline 125 kW - PEM
Production 30.4 scfm CH4 4.1 scfm CH4
CO2 Source AvedØre WWTP Delivered
Pressure 9 bar 18 bar
“The core of our power-to-gas system is a selectively evolved microorganism – a methanogenic archaea –
that excels through unprecedented catalytic ability and industrial robustness.”
http://www.electrochaea.com/about/
'. n
IHI
~ -l l 9
Scrent1fic Approach
•i Utilize excess el.ectricity production for the electrolys·si
of water to Hi2 and 02
•i Opfmized strain of methanogenic archaea to performi 1 trt ty
methanation under industrial conditionsi
., 98% Carbon efficiency of CO2 to CH4
• Post-processing for pipel"ne quaUty natural gas
----=---=--==--
Cubon Dk»dde r
s gnificanc a d I pact Bioca alysl
•i Potential long term storage stra egy via conversi,oni
of e ect icitv & CO2 to CH4
High efficiency CO2 capture and conversion strategyi
•i
•i
NRELDemonstrated route to renewable methaneiTransforming E RGY
MsoCalGas Electrocha a
A�' mpra nt>rgy tJIIDtyB_oCatProject !J A IOLOOIC I. CAUi,
NRE11 II
1)2)3)4)
ElectrolyzerPre-ProcessingBioCat ReactorPost-Processing