MAY 10, 2022
Blending Hydrogen
into the Gas Grid:
What Are the Impacts
Behind-the-Meter?
Paul Glanville, PE—R&D Director,
Building Energy Efficiency
Kristine Wiley—Vice President, Hydrogen
Technology Center
LOW-CARBON, LOW-COST ENERGY INNOVATION
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Why Blend Hydrogen? Near-term Decarb. at Scale
• Feasibility: Roadmaps emphasize near-term potential in blended H2
distribution in gas grids to end users
• Scale-up: With increasing scale/blend %, delivered H2 stimulates
demand, driving down generation/storage costs
– US/Canada network is 5.4 million km, serving 85 million customers!
Source: Hydrogen Roadmap Europe, https://www.fch.europa.eu/news/hydrogen-roadmap-europe-sustainable-pathway-european-energy-transition
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Why Blend Hydrogen? Near-term Decarb. at Scale
Fossil-Free Gas: Like efficiency and renewable
methane, many utilities view delivered H2 as
essential to long-term net zero emissions goals
Source: NW Natural’s Vision 2050, RNG Constrained scenario. Other market leaders with similar plans
include SoCalGas, Dominion Energy, National Grid, Enbridge, ATCO Gas, FortisBC, and many others.
And They’re Off! Numerous pilots are underway
now (typ. ≤ 20% H2 by vol.) with more homes and
businesses in receiving H2/natural gas over 2022.
Source: S&P Global. Add’l prominent pilots involving end users include those in Canada – British
Columbia, Alberta, Ontario, and Quebec; and USA - California, Minnesota, New Jersey, New Mexico,
New York, Oregon, Utah, and others.
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History Doesn’t Repeat, but it Rhymes
• Public gas distribution begins in US in 1816 (Baltimore)
• Gasified pine tar, coal, oil ~1000 US plants at peak (1890s)
• Syngas (H2/CO, “water gas” and “coal gas”), byproducts also sold
– Initially revenues were 90% lighting, then expanded into
domestic/commercial (via leasing), then industrial uses
• In 20th century, pipeline tech. brings “natural” gas to cities
Gas Works Park – Seattle (Decomm. 1956)
• Through 1930s, “enrich” mfd. gases by blending NG
(~2X HHV)
• Post-WWII favors straight conversion (DC, NYC)
– Conversion took 30-40 years in US, “single largest task” was
converting customer equipment (utility-led or contractor)
• Legacy of mfg. gas transition remains in appliance design/codes,
some current use (e.g., Hawaii Gas)
Appliance Design Guide (1944) – Still Used by Industry!!**
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* Source: Tarr, J. “Transforming An Energy System: The Evolution of the Manufactured Gas Industry and the Transition to Natural Gas in the United States (1807-1954),” in Olivier Coutard (ed.), The Governance of Large Technical Systems (London: Routledge, 1999),
19-37. // ** AGA Testing Laboratories, Primary Air Injection Characteristics of Atmospheric Gas Burners – Research Bulletin No. 26, 1944.
Flame Types
– Greater reactivity (flammability, ignition, temperature)
– No carbon (fewer emissions, humid exhaust, visibility)
– Premixed vs. Partially-Premixed matters!
• For typical, unadjusted equipment, look for:
– Startup issues: flashback/blowoff, ignition
Premixed
– Lower volumetric density/smaller size (de-rating,
embrittlement, etc.)
Partially-premixed
• Hydrogen has very different properties from natural gas
Partially-premixed
Non-premixed (Diffusion)
H2 as a Fuel: The Basics
Source: Arthur Jan Fijałkowski/ WikiCommons
λ=0
– Emissions impact: CO, NOx, etc.
0<λ<1
1≤λ
– Shift in heating: surfaces, de-rating, impact on efficiency
Wobbe Index (WI) used to
define fuel interchangeability
𝑊𝐼 =
𝐻𝐻𝑉
𝑆𝐺
Combustion Air Requirement Index
(CARI) predicts air/fuel ratio impacts
𝐶𝐴𝑅𝐼 =
𝐴𝑖𝑟/𝐹𝑢𝑒𝑙 𝑅𝑎𝑡𝑖𝑜
𝑆𝐺𝑓𝑢𝑒𝑙
Fuel Composition and λ can
predict SL and Tadiabatic, flame
where 𝜆1 𝐶𝐴𝑅𝐼1 = 𝜆2 𝐶𝐴𝑅𝐼2
©2022 GTI Energy. All rights reserved.
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H2 as a Fuel: Gas Quality and Tiered Approach
Hydrogen Blending as Gas Quality Issue
While impacts vary, general blending levels are:
Sp. Gravity
• Med. Blending (10%-30% H2 by vol.) Adjustments needed
• High Blending: (> 30% H2 by vol.) Specially-designed
equipment required (e.g., H2 Boiler)
Ground laid for “tiered approach” by extensive RD&D in EU/UK,
where “hydrogen ready” equip. are currently available
Index (100% CH4 = 1) at 60 F and Atm. Pressure
• Low Blending (< 10% H2) No or minor equipment
adjustments
HHV
Wobbe Index
Comb. Air Requirement
CO2
1.1
1.1
1.0
1.0
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
0.5
At 30% hydrogen blend, mixture:
- is 26% less dense
- has 20% lower HHV (vol.)
- has 7% lower Wobbe Index
- requires 23% less combustion air
- emits 12% less CO2 (energy adj.)
0.4
0.3
0.2
0.1
0.4
0.3
0.2
0.1
0.0
Source: THyGA Project (2021)
0%
10%
20%
30%
40%
50%
60%
70%
Volume % H2 with balance CH4
80%
©2022 GTI Energy. All rights reserved.
Source: Heating & Hotwater Industry Council (UK)
0.0
100%
90%
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H2 as a Fuel: Burner Impacts
Partially-Premixed Example
Premixed Example
Flame Sense/
Temp. Sense
Combustion
Controller
Premixed Surface
Combustion
Premixed
Fuel/Air
Premix Blower
Assembly
Fuel
Gas
Valve
Mixer
(Venturi)
Combustion Air
(1 .1 < λ < 1 .5, typ.)
Distribution Tube/
Plate Assembly
Ignitor(s)
Other potential config.:
blue-flame type burner,
pos t-blower fuel/air mixing,
electronic-type gas control
Pneumatic Signal (typ.)
Majority of: Furnaces/RTU, storage WH, cooking, hearth, outdoor
Most of: Hot water/steam boiler, pool/process heater
Increasing H2: Shifts λprimary to 1.0, can increase Tflame/SL, but impacts
are equipment specific on flame, heat transfer, air flow, NOx emissions
Majority of: Tankless WH, fuel-fired heat pump, mCHP
Most of: Low NOx versions of PP-type equipment
Increasing H2: Can shift λoverall leaner for pneumatic
controls, but compensating electronic controls (constant λ)
result in increased Tflame/SL
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Recent Results from Lab & Field
Common Concerns: In typical, unadjusted customer
equipment, will blended H2/NG…
• Cause equipment to immediately malfunction?
• Lead to unsafe operating temperatures?
• Adversely impact efficiency?
• Significantly reduce heat output?
• Increase NOx or CO emissions?
• Increase leakage within building?
Answers from important but limited datasets*
• Short-term tests only, often not North American context
• Inconsistent testing approach
https://www.mdpi.com/1996-1073/15/5/1706
Background, literature survey, results in recently
published GTI Energy paper – highlighting early
laboratory/field measurements up to 30% H2
©2022 GTI Energy. All rights reserved.
* :GTI Energy Glanville, P. Overview of Blended Hydrogen Impacts on Water Heating Equipment, 2021 ACEEE Hot Water Forum. / UC Irvine: link / CSA/AGA: link / https://thyga-project.eu/ AHRI - link / PRCI - link
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Recent Results from Lab & Field
Wait a minute, I thought 20% H2 was fine…
• 2013 NREL/GTI Energy study said 5%-15% H2 was “feasible with very
few modifications”
For CEC, UC Irvine found that a
common ULN Water Heater
could not operate ≥ 10% H2
while tankless could up to 20%
– Largely based on 2004-2009 EU NaturalHy study, different equipment
• Studies by AGA (2018) and PRCI (2020) point to up to 20% H2, but
knowledge gaps above 5% blended
• In Europe beyond NaturalHy, several pilots verify range
– Dutch pilot in Ameland, boilers/cooking equipment tested up to 30% H2
• CSA (2021) and UCI (2020) document some issues with common
equipment within these ranges →
• 2021 AHRI study, incl. FMEA, states up to 20% H2 OK for new
equipment, w/o adjustment – existing equipment may be replaced
For CSA, test lab could not
sustain ignition of vent-free
radiant space heater at 15% H2
©2022 GTI Energy. All rights reserved.
* GTI Energy: Glanville, P. Overview of Blended Hydrogen Impacts on Water Heating Equipment, 2021 ACEEE Hot Water Forum. / UC Irvine: link / CSA/AGA: link / https://thyga-project.eu/ AHRI - link / PRCI - link
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Recent Results – GTI Energy Methods
Scope of Testing - “Simulator” testing and In-situ
• Natural gas, 0%-30% H2 in CH4 in 5% increments
• Simulator tests operated manually: Furnace (in-shot), Water heater burners: Standard
NOx (2), Ultra Low NOx (2)
• For in-situ, appliances with automation of loads: Two furnaces (High/Std. eff.), Three
water heaters (Standard NOx, ULN #1, ULN #2)
In-situ Furnace Testing
In-situ Water Heater Testing
Furnace Burner “Simulator”
Water Heater Burner “Simulator”
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Recent Results – GTI Energy Methods
• Coordinated with utility team in mid 2021, GTI Energy
sampled emissions from 15 appliances
– Pre/post measurement of emissions (0%-10%),
material temperatures, observations on safety
– Water heaters (standard, Ultra Low NOx),
furnaces, ranges, dryers, fireplaces
• 2022 plans for three additional demonstrations,
expanding equipment population
GTI Energy sampling of residential furnace with 0% - 10% H2
blends (left) at facility “village” (right)
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Do Equipment Malfunction?
Standard NOx WH – 30% H2 / 70% CH4
• Based on GTI Energy Lab/Field Testing to date, generally
no issues in normal operation
• Ignition and sustained operation successful over 0%-30%
(lab), 0%-10% (field) for all equipment
• Minimal visual difference with “blue flame” burners, some
dimming of radiant burners
• Limited issues seen with UCI/CSA tests (noted)
ULN #1 WH – 30% H2 / 70% CH4
©2022 GTI Energy. All rights reserved.
Disclaimer: Conclusions based on results and methods of GTI Energy Projects/References noted only and may not be widely applicable
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Do Equipment Malfunction?
©2022 GTI Energy. All rights reserved.
Disclaimer: Conclusions based on results and methods of GTI Energy Projects/References noted only and may not be widely applicable
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Do Equipment Malfunction?
• Measurable delay in “rolling” ignition for furnaces,
increase with H2, cold vs. hot start, low vs. high fire
• “Flashback” created outside of furnace testing plan,
but uncertainty why?
Simplified Flame
Flame Speed
Fuel/Air
λ < 1 (Partially Premixed)
λ > 1 (Premixed)
If VFuel/Air >> VFlameSpeed
Blowoff
If VFuel/Air << VFlameSpeed
Flashback
30% H2 / 70% CH4
70% CH4 / 30% H2
25% H2 / 75% CH4 – 0.12 speed
0.12X Speed
©2022 GTI Energy. All rights reserved.
Disclaimer: Conclusions based on results and methods of GTI Energy Projects/References noted only and may not be widely applicable
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How is Heat Output Impacted?
Reduced slightly in excess of Wobbe Index shift, consistent result in literature
• GTI Energy data vs. output measurements in EU literature review
For GTI Energy tests water heater input results consistent,
but nuanced results – ULN #1 near exact with Wobbe Index
From THyGA project literature review focus on output, similar
results seen though wide range in impact
Data Source – THyGA Project: https://thyga-project.eu/deliverable-d2-3-impact-of-hydrogen-admixture-oncombustion-processes-part-ii-practice/
©2022 GTI Energy. All rights reserved.
Disclaimer: Conclusions based on results and methods of GTI Energy Projects/References noted only and may not be widely applicable
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Do NOx and CO Emissions Increase?
Generally, no. GTI Energy data show reduction in NOx across the board (energy input
adjusted) and small change in CO emissions
Ultra Low NOx #1 “Slug Test”
©2022 GTI Energy. All rights reserved.
Disclaimer: Conclusions based on results and methods of GTI Energy Projects/References noted only and may not be widely applicable
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Do NOx and CO Emissions Increase?
Generally, no. GTI Energy field data show flat/reduction in NOx emissions (within error)
Location
Equipment Name
Burner Type
A
Water Heater #1
“Pancake” Burner
B
Water Heater #2
“Pancake” Burner
D
Water Heater #3
ULN Burner #2
E
Water Heater #4
“Pancake” Burner
D
Furnace #1
“In-shot” Burners
E
Furnace #2
“In-shot” Burners
B
Wall Furnace #1
“In-shot” Burners
G
Wall Furnace #2
“Ribbon” Burners
C
Fireplace #1
Perforated Burner
A
Range/Oven #1
Standard Range Burner
E
Range/Oven #2
Standard Range Burner
F
Range/Oven #3
Standard Range Burner
Water Heater
Furnace
Range
Oven
©2022 GTI Energy. All rights reserved.
Disclaimer: Conclusions based on results and methods of GTI Energy Projects/References noted only and may not be widely applicable
19
Recent Results - Recap
Based on data collected to date in typical, unadjusted customer
equipment, will blended H2/NG…
• Cause equipment to immediately malfunction? Not likely
• Lead to unsafe operating temperatures? Not likely
• Adversely impact efficiency? Not likely
Source: Northern Gas Networks
• Significantly reduce heat output? In excess of Wobbe
• Increase NOx or CO emissions? Generally, no
• Increase leakage within building? Not worsened by blending
But what about..
• Higher blends/pure hydrogen? Long-term impacts? Testing to failure?
• Broader population of equipment (type, age, installation)? Emerging
technologies and retrofit packages?
Source: Gersen, Van essen, 2020
©2022 GTI Energy. All rights reserved.
Disclaimer: Conclusions based on results and methods of GTI Energy Projects/References noted only and may not be widely applicable
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H2 Blending Impacts on Equipment – What’s Next
• Continued testing/sampling of more diverse
equipment (e.g., H2 heat pumps), indoor
distribution leakage, use of in-line H2 sensors
• Coordinate/support update to codes and
standards impacted by H2-based fuels
• Development of mitigation tech. and high-H2
tolerant components/equipment
• Recent ~$3 million award to GTI Energy-led team
on H2 in large comm. and industrial applications
– Test/model H2 tolerance of wide range of large
equipment categories (e.g., boilers)
– Material testing for long-term impacts, Air Quality
simulation to quantify regional benefits/impacts
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Thank You!
For More Information
Paul Glanville, PE
R&D Director, Building
Energy Efficiency
Kristine Wiley
Vice President, Hydrogen
Technology Center
Watch for a
follow-up survey
Research discussed supported by Utilization Technology Development (https://www.utd-co.org/)
Research team on H2 Impacts in Buildings: Alex Fridlyand, Brian Sutherland, Frank Johnson,
Kaushik Biswas, Kris Jorgensen, Luke Bingham, Will Asher, Yan Zhao, and others
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