Esposito Research Group Highlighted in H2 Newsletter



The Esposito Research Group at Columbia University was highlighted in the February 2019 newsletter put together by the International Association for Hydrogen Energy (IAHE). The IAHE is an organization that promotes hydrogen as a key energy carrier in a sustainable energy future by organizing H2-oriented scientific conferences, running a peer-reviewed journal (International Journal of Hydrogen Energy), and coordinating a number of other activities that generally support the spread of information on hydrogen-related technology.  H2-enthusiasts can become members of the IAHE through their website, and students can join for free to receive the IAHE E-newsletter by emailing John Sheffield at for more information.

The full February 2019 IAHE newsletter can be found here, with the feature highlighting the Esposito Research Group (pgs. 31-33) is copied below:


Research Lab Highlight

Esposito Research Group, Columbia University
The following is a Q&A interview with Professor Daniel Esposito, the group’s director.
By: Anirban Roy
Q. Tell us a little about your research group and the work you focus on?
A. Our group is comprised of a very talented mix of Ph.D.,
postdoc, MS, and undergraduate researchers, and our research
interests relate broadly to electrochemical technologies
that are able to convert sunlight or solar-derived
electricity into storable fuels and chemicals. We are
based in the Department of Chemical Engineering at Columbia,
and are core members of the newly formed Columbia
Electrochemical Energy Center (CEEC). The majority
of our research focuses on developing electrocatalytic
materials and devices for electrolysis and fuel cell technologies.
These efforts are strongly complemented by advanced
analytical tools, such as scanning electrochemical
microscopy (SECM) and in situ high speed video, which
allow us to probe the properties and performance of electrode
materials with high spatial and/or temporal resolution
(see more below). Research projects in our lab are
funded by a mix of government and industry sponsors,
and address a wide range of questions spanning basic
science to application-driven design problems. Presently,
major ongoing research projects in our group include the
development of i.) encapsulated electrocatalysts and ii.)
membraneless electrochemical cells, both of which offer
exciting opportunities to impart new functionalities in
electrolyzers and fuel cells that are not possible with conventional
electrocatalysts and devices.
Q. What is your research methodology?
A. An important part of my research methodology is how
I choose the problems I work on. One of the things that
most strongly motivates my group’s research is the possibility
of developing a new material or device that can lead
to transformative impacts on our energy system. The climate
challenges society faces are real and urgent, and
incremental improvements in clean energy technologies
are not going to be enough. Thus, when I come up with a

new project idea to pursue, I always ask myself if that idea
has a chance to directly or indirectly lead to a step change
in one or more key performance metric (s). If not, I generally
shy away from pursuing it further. Naturally, this
leads one to pursue unconventional ideas that have lower
chances of “success” (in the traditional sense), but creates
a greater chance of discovering something that has real
potential to significantly extend our knowledge envelop
and lead to game changing technology. To explore high-risk
ideas, or any advanced/complicated research question
for that matter, I like to start simple and build up in
complexity. Thus, we do a lot of work with model electrode
surfaces and “as simple as possible” devices that
can allow us to better understand the fundamental physics
and chemistry that underlies their operation, and more
quickly get to the point to where we can test key hypotheses/
ideas. Concurrently, I think it is essential to address
difficult research problems with cutting edge experimental
and computational capabilities. For this reason, we
put a lot of effort into developing new in situ analytical
tools and methodologies (see more below), and actively
collaborate with others who are experts in techniques and
methods that are complementary to our own.

Q. There has been a recent trend in scientific research to
perform “in-situ” experiments. What are your thoughts on
“in-situ” techniques?
A. We’re big proponent of using in situ techniques to
study electrochemical materials and devices whenever it is
reasonable to do so. Whether we are talking about a
spectroscopy, imaging, or electrical measurement, we almost
always prefer in situ measurements over ex situ
measurements, and we want that tool to give us as much
information as possible. The computational capabilities of
our colleagues who specialize in modelling/theory are improving
at a rapid rate, and we experimentalists need to
keep up! When studying electrode materials, in situ measurements
are capable of providing invaluable insights
about material properties/characteristics that can be very
different from those observed for the same material when
measured outside of the electrochemical environment.
When studying electrochemical devices, in situ imaging
techniques with high spatial and/or temporal resolution
offer the ability to gather rich data sets that can be of
great value for i.) validating models, ii.) diagnosing issues,
and iii.) guiding the design of optimal geometries.

All of that being said, in situ measurements often pose
significant challenges to carry out successfully, and are
not for the faint of heart! The design and construction of
new in situ experimental capabilities often require substantial
time/cost/blood/sweat/tears, and the measurements
themselves might ultimately be a step removed
from the operating conditions of a real electrolyzer or fuel
cell. However, the potential payoff for these efforts are
huge, especially if they can help create a link to emerging
computational technologies with the ability to accelerate
the design and prediction of materials/devices.
Q. Your thoughts on hydrogen as viable future resource
energy carrier?
A. I have tremendous optimism for the role that hydrogen
(H2) will play as an energy carrier in a sustainable energy
future. Much of this stems from the ability to obtain clean
H2 fuel at large scale using renewable energy by water
electrolysis in the absence of any CO2 emissions (or any
carbon at all). The other feature that makes H2 so attractive,
in my mind, is its versatility as a fuel and chemical
that can be used by almost every energy sector. We as a
society rely extensively on fuels today due to their many
desirable properties (high energy density, negligible “self-discharge”,
application at large scale) and I am confident
in saying that fuels will continue to play an important role
in a future sustainable energy system. I believe that H2,
both as a fuel itself, and as an intermediate used to upgrade
CO2 into liquid hydrocarbon fuels, will be the foundation
of that future fuel mix.
Q. What are the key research areas that need to be addressed
for a feasible Hydrogen economy? (Also mention
your contributions)
A. H2 economy only makes sense in the long run if the
vast majority of that H2 is “green hydrogen” that is produced
without any associated greenhouse gas emissions.
Preferably, that hydrogen is produced by water electrolysis
using renewable electricity, in which case carbon is
completely removed from the equation. We have commercially
available technology for producing, storing, and
using hydrogen produced from water electrolysis in a safe
and scalable manner. The biggest barrier to widespread
implementation of these technologies is the cost of hydrogen
energy compared to fossil fuels like natural gas and oil.

Fortunately, the falling prices of electricity from solar photovoltaics
and wind are making the economics of H2 production
from water electrolysis more favourable. However,
low-price electricity (0.02 $/kWh) will not be enough to
tip the balance in favor of H2. Additionally, it will be essential
that the capital costs of electrolyzers and H2 storage
technologies be brought down to levels that are substantially
below where they are today. This is especially
important in a renewable energy future when low-price
electricity becomes commonplace, but only for a small
fraction of the day. This realization was a key motivating
factor behind my group’s work with membraneless electrolyzers,
which possess very different architectures and
operating principles from conventional PEM and alkaline
electrolyzers. These membrane free devices have potential
for low-cost manufacture (see more below) as well as durable
operation in harsh environments where conventional
cells would not be stable due to fouling or blocking of
the membrane or divider. In my opinion, developing materials
and device architectures that can have longer lifetimes
and be more robust in the presence of impurities
will be of great importance, and requires a lot of additional
research efforts. Towards this end, my lab also has substantial
effort to develop electrocatalyst materials that are
encapsulated by ultrathin permeable overlayers that can
help to mitigate nanoparticle coalescence/detachment, as
well as block impurities or unwanted reactants from
reaching the catalytically buried interface. Beyond efforts
to develop more durable/tuneable electrocatalysts and
low-cost devices, I think it will also be important for researchers
to make progress on developing low-cost nonprecious
metal electrocatalysts without compromising on efficiency.
Q. What were your inspirations behind the 3D printed
membraneless electrolyser, and the concept of a solar PV
coupled floating electrolyser?
A. The earliest inspiration for the membraneless electrolyzers
we work on in my lab came from reading articles on
membraneless laminar flow fuel cells and flow batteries
developed by Paul Kenis’s lab at Illinois, with later work by
Martin Bazant’s lab at MIT. I was struck by the simplicity
of those device architectures, and the ability to use fluid
flow to achieve efficient separation of electrochemically
generated products in the absence of any membranes.
However, those cells were relatively small-scale microflu-

idic devices. About 5-6 years ago I came across an image
in a National Geographic article (that had absolutely
nothing to do with electrochemistry or hydrogen!) of a
porous material, which lead me to think about ways that
porous flow-through electrodes might be used in scalable
membraneless electrolyzer architectures. Fast forward to
today, and the electrodes/devices that we are currently
working on are almost unrecognisable from some of the
first sketches that I and my students came up with.
As mentioned above, we are interested in exploring membraneless
electrolyzers as robust devices that can reduce
capital costs far below those of conventional cells that are
built around membranes/dividers. Membraneless electrolyzers
offer an avenue to achieve this goal by reducing the
number of device components and the cost of manufacturing/
assembly. The floating membraneless PV-electrolyzer
concept was an extension of this logic. After
getting rid of the membrane and the pump, we decided
to simplify the system even further by integrating the PV
and electrolyzer while simultaneously removing the need
for solid ground for the technology to operate on.
Around 70% of the earth’s surface is covered by water;
why not use a tiny fraction of it for energy harvesting? It
is fun to think about a future floating “solar fuels rig” operation
that uses abundant and cheap solar energy and
seawater to generate H2 at large scale. Others in the solar
fuels field have thought about this concept before as well,
but we were, to the best of my knowledge, the first to
demonstrate a standalone, floating PV electrolyzer. That
work was based on a relatively small prototype, and there
are many significant challenges associated with producing
H2 from seawater, but we hope that demonstration might
provide inspiration for other groups to help us move the
concept closer to reality.
Q. What is your advice for the young generation, who are
willing to contribute to science, engineering and a better
sustainable society?
A. In order to achieve a sustainable energy future, we
need “all hands on deck”. Climate change is one of the
grand challenges of our time, and it is critical that we
have our best and brightest young minds go into science
technology engineering and math (STEM) fields with the
goal of developing clean energy technologies that will
help to mitigate the effects of climate change. There

could not be a more important time to enter into this field
and make a difference. Additionally, I would encourage
students to exercise their creative thinking muscles whenever
possible in order to better develop into the innovators
that we need. I suggest that students and young
professionals alike try to reserve a half day a week to let
their minds wander away from structured course work
and “normal” research plans to brain storm new ideas.
Unfortunately, incremental changes in today’s clean energy
technologies are not going to be sufficient to reverse
the trend in CO2 emissions as quickly as we need them to.
Innovative new ideas that lead to step changes in the economics
of these technologies are a must, and I have no
doubt that this generation of young scientists will develop
those technologies if they can realize their creative potential.


Columbia Electrochemical Energy Center (CEEC) Announced


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Based in the School of Engineering and Applied Sciences (SEAS), Columbia has officially lunched the Columbia Electrochemical Energy Center (CEEC). There are nine core faculty members in the center,  which brings together interdisciplinary teams of students and faculty from chemical, earth & environmental, mechanical, and electrical engineering to tackle grand challenges in electrochemical energy conversion technologies.  Find out more about the center in this SEAS press release and/or check out these videos promoting the new center:




Pulling CO2 from air- within reach!

It is well established that this planet has a problem with rising concentrations of carbon dioxide (CO2) in the atmosphere. While the most commonly explored solutions to this problem involve technological and conservation efforts that decrease the rate at which CO2 is released into the air, there is another:   directly remove CO2 from the atmosphere.  Once removed, the CO2 can be sequestered or converted into something useful such as a fuel or material.

Researchers have considered this second option for many years, but the technologies needed to pull CO2 from air have been generally considered too expensive to be realistic, with costs generally predicted to be > $600 per ton of CO2 harvested from the air. Excitingly, it has been recently reported that the cost of direct air capture (DAC) can be substantially reduced.  As discussed in the following editorial on and described in detail in an article published in the peer-reviewed journal Joule, scientists and engineers at a Canandian company, Carbon Engineering, have performed a technoeconomic analysis on a DAC system based on well-established commercial technologies that predicts carbon capture at levelized costs of $94- $214 per ton of CO2.

For perspective, if the captured CO2 were converted into a fuel such as methanol, the capture cost would add 0.4-0.8 cents per gallon of methanol produced. In North American, methanol currently sells for ~ $1.64 / gal., so making methanol from DAC CO2 using conventional methods would currently add ~ 25-50 % to the cost. Not bad! As DAC and CO2 conversion technologies continues to improve, such a circular Carbon technology is very likely to become a reality.

MOU signed for world’s largest solar plant


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It was recently announced that a memorandum of understanding (MOU) has been signed to construct the world’s largest solar photovoltaic (PV) plant in Saudi Arabia. When the sun is shining, the plant will have a generating capacity of 200 GW.  By comparison, the size of this plant (when completed) will be 5 times larger than the total installed PV capacity in the U.S. and nearly 1/5th of the entire electricity generating capacity in the U.S.. You can read more about the planned PV plant here.

This announcement reaffirms what many in the PV and electricity industries already know:  solar absolutely has the ability to power the planet, and it is possible to get to that point in the near future.

Hydrogen Milestone in Japan


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It was recently announced that Japan will be opening its 100th Hydrogen fueling station this Spring, making it the first country in the world to reach this milestone.  According to the article below, Japan has been greatly expanding its hydrogen fueling infrastructure as it expects to have 40,000 hydrogen fuel cell vehicles on the road by 2020.

By comparison, there are currently around 40 hydrogen fueling stations in Germany and 30 in the U.S..

New Records for Batteries & Electrolyzers


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There were two recent announcements relating to the installation of battery and electrolyzer technologies that broke world records:

1. Proton Onsite / Nel ASA just announced a contract to supply a PEM-electrolyzer based H2 generation and fueling station that will supply up to 900 kg per day of H2 that will be used for fuel in H2 fuel cell buses in the Palm Springs area of California.  The size of this combined electrolyzer / fueling station makes it the largest such station in the world.  For perspective, 1 kg of H2 is roughly equivalent to 1 gallon of gasoline, and an average convenience store gas station in the U.S. sells about 4,000 gallons of gasoline per day.  So, it will be desirable to make these systems even bigger in the future. You can read more about the Nel ASA fueling station here.

2.  Tesla is half way finished building a Li-ion battery system that will be installed in Southern Australia. Once installed, this system will be rated at 100 MW with 129 MWh of capacity, making it the largest grid-tied battery system in the world.  For perspective, a typical coal-fired power plant produces around 1000 MW of electricity.   You can read more about the Tesla installation in Australia here.

Both California and Australia have been aggressive installing renewable wind and solar, which has resulted in large price fluctuations in both locations, leading at times in negative electricity prices.  Using these free or low-cost electrons to to produce fuels or charge up a battery until electricity prices return to normal represent a huge opportunity for these energy storage technologies to grow.



“The Grid’s Great Balancing act”^ – status in California and China


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It’s no secret that there will be significant challenges to achieving a clean energy future where a large percentage of society’s energy comes from renewable resources such as solar and wind.  Many of these challenges relate to the fact that solar and wind are variable and sometimes intermittent generators– they only produce electricity when the sun is shining and the wind is blowing.  Thus, the amount of electricity supplied by these resources is often out of sync with the demand for electricity, an issue that gets worse as solar and wind achieves a larger percentage of a region’s generating capacity. In order to deal with the imbalance with supply and demand, a combination of three actions are often taken:

  1. The price of electricity decreased. Sometimes, electricity prices can even go negative, with a state like CA having excess electricity paying states like Arizona to take the extra electricity off their grid (see article below).
  2. Conventional power plants, such as natural gas plants, are turned off/on to help balance demand and supply.
  3. Excess electricity from solar and/or wind is curtailed, meaning the connection between the solar panel or wind turbine and the grid is cut, and the electricity is wasted. (free electricity!).

In California, where almost 14% of its electricity was obtained from solar in 2016, this grid balancing act is already becoming extremely challenging, as discussed in a recent LA Times article that provides a lot of useful stats and discussion:

In China, which is the world leader in solar panel production and increasingly installing large amounts of solar power plants itself, the imbalance between electricity supply and demand is become especially acute in provinces where transmission of electricity to the large population centers is highly inadequate.  According to the article below, curtailment rates of solar-generated electricity are often 30% or higher!:

While improvements to the grid (e.g. smart grid technologies) and demand-side management can go a long way to help alleviate some of the issues involved with balancing electricity supply and demand, there is a limit to how much they can help—especially in a future where solar and wind generate 50% or more of a region’s electricity.  In this case, many studies agree that low-cost and scalable energy storage technologies are crucially important.   Batteries are one option, and have the benefit of high round trip efficiencies, but electrolyzer technologies that convert electricity into storable chemical fuels are another option.   Electricity-to-fuel technologies such as the ones we work on in our lab also represent a huge opportunity because fuels can be used for many energy applications and sectors that are not currently very reliant on electricity.  The flexibility and storability of fuels thus make them highly attractive 1.) for their ability to utilize low-cost or free electricity, and 2.) their ability to impact many different energy use sectors (transportation, industrial/chemical, agriculture, commercial) that are predominantly reliant on fossil-fuels at this time.

^credit: the term “The grid’s great balancing act” has been often used by Prof. Cory Budischak at Delaware Technical Community College. A more detailed analysis of a future scenario in which  99.9% of the electricity is provided by solar and wind can be found in a paper that he published a few years ago in J. Power Sources:

Hydrogen in Japan, Australia, and the US

There were a couple of recent articles on the growing hydrogen fuel cell vehicle (HFCV) market:

  1. Japan is investing heavily in it’s hydrogen infrastructure. With 80 H2 refueling stations already installed, Japan plans to increase that number to 160 stations supporting 40,000 HFCVs by 2020 when it will host the summer Olympics:
  2. In the US, HFCVs are currently confined to California, which currently has 30 fueling stations, with plans to expand to 100 stations by 2020.  However, as reported in this recent New York times article, H2 fuel stations will start appearing in the Northeast between New York and Boston later this year, with several planned for the greater NYC area:
  3. In all future hydrogen markets, infrastructure can be a limiting factor because it can be very expensive to build new stations, piping networks, and H2 generation plants to support HFCVs. In a renewable energy future where H2 is produced by water electrolysis driven by energy from wind and solar, a challenge is building this infrastructure that links remote generation sites with lots of solar and wind to densely populated areas where most of the demand will be.  In Australia, where there is ample space, sunlight, and wind, there has been discussion of becoming an “hydrogen exporter”, where domestically generated H2 will be shipped as liquid Hydrogen to various locations around the world in H2 tanker ships like the one shown in the rendering below:

Australia and Japan signed a deal in January 2017 to ship liquid hydrogen in bulk from Victoria, in what will be a world first. A pilot project is expected to start in 2020. Supplied artist’s impression of a liquid hydrogen carrier from ship-builder Kawasaki Heavy Industries.

Artist’s rendition of a tanker that will ship liquid H2 from Australia to Japan as a part of a deal between those two countries that will begin a pilot project in 2020. Image source is the above cited article in the Guardian.

More Solar PV Installed in US in 2016 than Any Other Electricity Source


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In a preview of a soon-to-be released annual report from the Solar Energy Industries Association (SEIA) and the GTM research, it has been reported that the electricity generating capacity of solar photovoltaic (PV) installations added to the US electrical grid in 2016 was higher than any other type of electricity generating technology. 39% of all new electricity capacity, equivalent to around 14.6 GW, was added in 2016, a 95% increase from 2015. Together, new solar and wind installations comprised 65% of all new electricity generating capacity in the US, reflecting the fact that the costs of solar PV installations have been cost competitive with traditional sources across much of the US.

As the price of electricity from solar PV continues to drop, this creates a huge opportunity to use electrochemical technologies to convert low-cost, carbon-free electricity into storable chemicals and fuels.


Plot of new electricity generating capacity in the US by year and type of technology. Source: Source: GTM Research / SEIA U.S. Solar Market Insight Report

An Update on H2 Fuel Cell Cars (and Trucks!)


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This recent article gives a nice summary of the state of H2 fuel cell vehicles in the U.S. and around the world with a focus on describing plans by a company out of Utah (Nikola) to develop a nation-wide H2 refueling network for hybrid H2/electric tractor trailers or semis:

You can see a map of the approximate locations of the planned fueling stations here. “Big rigs” are an exciting opportunity for H2 fuel cells because their larger size (fuel tanks) can be leveraged to give them a long range (distance traveled between fueling), and unlike an average private vehicle, it’s more common for a truck to a few well-defined routes. Thus, an early fleet of trucks can get by on fewer fueling stations.  Importantly, an analyst at the Union of Concerned Scientists notes in this  article that although big rigs only make up 7-10% of the vehicles on the road, they consume 25% of the fuel.

Although the H2 refueling network in the US is currently confined to California, the article above reports that a network of stations will soon be installed in the Northeast, and points out that extensive systems are in place or being built in other countries in the world like Denmark, Japan, and Germany.