Sunday, May 1, 2022

Hydrogen Myth Busting (Episode 2)

Global temperature anomalies (Source: NASA GISS)

In my previous post, I started to address some common and recurring myths about hydrogen. This post will continue along the same theme, but with myths that have more nuances to unpack.

Myth #5: Making Hydrogen From Renewables Isn't Practical

There are multiple variations on this myth. Some of the most persistent of them include:
  • There aren't enough renewable resources to support all the carbon-free hydrogen production needed
  • Renewables should only be used to directly meet the electrical demand; producing hydrogen with them is wasteful
  • Conclusions regarding hydrogen production from renewables specific to a particular region are globally true everywhere

    Not enough renewables

Let's start with the first variation. A typical set up for this argument is that if all fossil fuel applications were immediately switched to hydrogen there wouldn't be enough renewable energy capacity to support its production. 

The fundamental flaw with this argument is that every energy transition occurs over decades; there has never been and will never be an immediate transition to any new energy paradigm. If this argument had carried the day prior to the industrial revolution, our energy and transportation systems would still be based on horses.

Hydrogen production using renewables is growing via the deployment of new solar, wind and other generating capacity. These renewable resources can be used during periods of over-generation (more on this below), or supplied from dedicated new microgrids.
    Renewables should only be used for electrical demands 

In a fantasy computer simulation, it may be possible to make the sun shine and the wind blow whenever needed to perfectly match the electrical demand at all times. Unfortunately, electrical demand never matches available renewable energy in the real world.

The historical solution to this problem has been to use base load generating sources such as coal-fired or nuclear power plants plus peaking capacity (e.g. natural gas or diesel) to balance power vs load. However, as more renewables come on line, this balancing act becomes untenable when renewables reach about 30% or more of the generating mix.

As fossil fuel generating capacity continues being replaced by cheaper renewables, energy storage will become increasingly necessary to maintain the balancing act. If the local geographical features support pumped hydro (water) storage, that may be the cheapest and simplest solution for that locale. If the scale is not too large, batteries may also provide a reasonable solution.

But for large grids, or microgrids that also incorporate fueling functions, hydrogen is the solution that can be implemented anywhere at any scale. And the lifecycle costs and supply chain risks are lower than batteries under these conditions for an equivalent storage capacity.

    The same hydrogen solution applies everywhere

Consider a densely populated small region in the upper northern hemisphere with limited solar irradiation and no real estate for wind power. Large scale production of hydrogen from renewables in this region may not make much sense.

Now consider a sparsely populated larger region near the equator or in the southern hemisphere where there is an abundance of solar and wind resources and vast real estate available at a low price. Hydrogen production from renewables in this region is not only feasible but may represent a lucrative export opportunity. It can be transported to that densely populated region similar to oil or liquified natural gas.

Between these two extremes are a plethora of regions with varying natural, economic, and geopolitical conditions that dictate what type of hydrogen infrastructure makes sense for that location. And yet it is not uncommon to see articles and policymakers who declare a recent study for a specific region to be "the answer" on how hydrogen should be implemented globally.

Myth #6: Hydrogen Isn't Green

As with the previous myth, there are variations on this one:
  • Since most hydrogen has historically been produced with steam methane reforming (SMR), it isn't a solution to climate change
  • Hydrogen may contribute to global warming

    Hydrogen production

Hydrogen and lithium ion batteries can be used to store energy. When that energy is used, no carbon byproducts are emitted. These are simple irrefutable facts based on the associated chemical processes.

If the feedstock for producing hydrogen is water that is electrolyzed using solar or wind, then it is a "green" method of production. If batteries are charged using the same renewables, then the charging process is green.

Neither hydrogen nor batteries are inherently green or not... it is the lifecycle ("cradle to grave") processes associated with them that determine the impact on the environment. In the case of hydrogen, the number and capacity of electrolyzer installations powered by renewable energy are growing rapidly and represent a truly green source of energy storage and fuel.

    Hydrogen leaks and global warming

This relatively new myth is based on a recent study that has been warped beyond recognition to produce tabloid worthy - and grossly inaccurate - headlines. The study in question poses the following (paraphrased) scenario:
If hydrogen were to be produced in the quantities required to replace fossil fuels; and large aggregate leaks of hydrogen were permitted to occur throughout this new global hydrogen infrastructure; and furthermore, these leaked quantities of hydrogen managed to reach the upper atmosphere without already combining with oxygen in the lower atmosphere or water; it may combine with hydroxides in the upper atmosphere to form water vapor.

 So what's the issue? Keep reading...

This process may inhibit the amount of upper atmosphere hydroxides available to react with the large amounts of leaked methane; thereby inhibiting the ability to mitigate the impact of methane sources and leaks.

While methane is a very potent and prevalent greenhouse gas, it's rather difficult to overlook the circular argument of this scenario. Namely, that transitioning to hydrogen might inhibit the upper atmosphere mechanism that helps to mitigate the greenhouse gas effects of one of the fossil fuels that hydrogen will replace.

The study goes on to recommend that implementation of global hydrogen infrastructures should address leakage to ensure very little reaches the upper atmosphere. The methods and technologies for minimizing hydrogen leaks are well known within the hydrogen community and are already used in any appropriately designed system.

This is a key takeaway and valid consideration as we transition to hydrogen. Unfortunately, that valuable nugget rarely seems to make its way into the subsequent articles that misrepresent the findings. Instead, a more sensationalized tale is spun about the effects of large scale hydrogen usage and greenhouse gases. While that may draw a lot of readers, click-throughs, and online traffic, it is clearly misleading.

Myth #7: Any Particular Technology is the Only Solution

Lithium-ion batteries have evolved to become a truly amazing energy storage technology. High round trip efficiencies during charge and discharge cycles. Portability ideal for very small scales up to automobile applications. Continuing improvements that extend useful life before replacement is necessary.

Li-ion batteries also have their weaknesses. Charging time and heating; temperature effects on performance; thermal runaway if punctured or crushed; strategic materials issues; recyclability; limited practical scalability; weighs the same fully charged as fully discharged.

Hydrogen has its own strengths and weaknesses. Its much higher energy density relative to batteries extends the range and capacity of land, air, and marine electric vehicles. And the vehicle becomes lighter as the hydrogen is consumed, unlike batteries. There are no strategic material nor recycling issues. The operational lifetime of hydrogen systems are measured in decades. Hydrogen systems are scalable to meet very large energy storage requirements, and any application that currently uses fossil fuels.

On the downside, hydrogen has lower round trip efficiency when used in a fuel cell compared to Li-ion batteries (although much higher than any combustion process). High compression as a gas or liquefaction at cryogenic temperatures is required to overcome its otherwise low volumetric density. And workforce training is needed to ensure the required skillsets are sufficiently available for properly designing, commissioning, and operating new hydrogen infrastructures.

Other solutions that reduce or eliminate greenhouse gas emissions have their own unique pros and cons. No single technology or solution is universally optimal for every application. The path to a more secure energy and environmental future requires careful consideration of all feasible options that get us closer to that goal. An important step forward is dispelling myths promulgated by vested interests or the misinformed.

    Matt Moran is the Managing Member at Moran Innovation LLC, and previous Managing Partner at Isotherm Energy. He's been developing power and propulsion systems for more than 40 years; and first-of-a-kind liquid, slush and gaseous hydrogen systems since the mid-1980s. Matt was also the Sector Manager for Energy & Materials in his last position at NASA where he worked for 31 years. He's been a cofounder in seven technology based start-ups; and provided R&D and engineering support to hundreds of organizations. Matt has three patents and more than 50 publications including the Cryogenic Fluid Management report series. More about him can be found here.