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) 815-3721Kevin.Harrison@nrel.gov

Nancy Dowe Senior Scientist - Microbiology National Renewable Energy Laboratory (720) 227-2009Nancy.Dowe@nrel.gov

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