|Day operation HyERA™ example system model: renewable power is greater than demand yielding hydrogen production and storage|
A recurring question when it comes to hydrogen is whether it is an energy carrier, an energy storage method, or a fuel. The answer is yes. This versatility is why hydrogen represents a key solution to mitigating climate change across virtually all industry sectors.
No carbon emissions. No harmful environmental impacts. No strategic materials supply chain issues. No disposal or recycling challenges. And with a system lifetime measured in many decades with routine maintenance and no significant replacement costs.
There is another truly unique capability of hydrogen systems that is often overlooked: the capability to produce large quantities of potable water. But first, let's start with its role as an energy carrier.
An energy carrier is a fuel or system that enables the conversion of potential energy to other forms of energy (e.g. mechanical, thermal, chemical, or electrical). The conversion process can be shifted in time, location, or both relative to when and where the potential energy was originally created.
A common and currently ubiquitous example is natural gas. Produced by decaying organic material, it has intrinsic potential energy in the form of its heat value (a measure of energy density). It can be delivered as a gas in pipelines, or liquefied for transport. Unfortunately, natural gas is a significant source of greenhouse gas emissions via leaks and combustion emissions.
Hydrogen has all the energy carrier characteristics of natural gas without the greenhouse gas or other environmental impacts. It can be similarly delivered as gas, or liquefied for transport. Its heat value is more than double that of natural gas or any other fossil fuel. Further, the energy conversion efficiency when hydrogen is consumed in a fuel cell is much higher than any combustion process.
Energy storage methods retain energy from a power source and store it for later use. This capability is particularly critical for balancing electrical demand in grids or microgrids that rely wholly or in part on intermittent renewable power sources (e.g. solar or wind).
Commonly used forms of energy storage include hydroelectric (i.e. "hydro") for large scale storage, and lithium-ion batteries for small to moderate energy storage. For grid-scale energy storage where the local terrain doesn't support hydro - which is most locations - there are few feasible options and even fewer proven systems. Lifecycle battery costs at this scale become untenable.
Overgeneration from renewables that is currently curtailed when insufficient demand exists can be used to electrolyze water into hydrogen and oxygen. The hydrogen is then stored until demand exceeds renewables capacity, at which point it is fed to fuel cells to generate the additional electricity needed.
Hydrogen energy storage is rapidly being recognized as a frontrunner solution for large scale applications where it has already been deployed in many locations. And more capacity is coming online at an accelerated rate.
As previously mentioned, hydrogen has more than double the energy density of any fossil fuel option. It has been successfully demonstrated in nearly every combustion process imaginable, from internal combustion engines to turbines. Adjustment of the oxygen-fuel ratio is the primary modification required.
Ground, sea, and air demonstration vehicles using hydrogen have already been fielded with many more under development. These applications particularly benefit from the increased energy density of hydrogen relative to legacy fuels. And of course, carbon emissions are eliminated.
Over the last few years, introduction of a low percentage of hydrogen into natural gas pipeline networks has been tested in several global regions with promising results. Modification to residential and industrial burners will be required to increase the hydrogen percentage to more than 10%.
In short, there are no current fossil fuel applications that cannot be transitioned to hydrogen. Additionally, the higher flame temperatures that can be achieved with hydrogen will enable new applications and potentially enhance the efficiency of existing combustion-based systems.
The fact that hydrogen can be produced from water using renewable energy sources, and then returned to water form during usage, is generally well known. But many other feedstocks can be used to produce hydrogen. And when the hydrogen is used, potable water can be extracted in significant quantities.
Two of the more intriguing feedstock options are seawater and biomass waste. A hydrogen electrolysis plant located near a coast or on an island could desalinate seawater and produce hydrogen for energy storage, fueling, and/or export.
Likewise, dual production of potable water and hydrogen can be realized with agricultural waste and other recycled biomass as feedstock. In this case, potable water and hydrogen can be generated where little or no water is available.
The implications for drought stricken regions is immense, particularly where renewable resources such as solar are available in abundance. Secure and reliable energy, water, and food becomes possible in regions that are vulnerable to weather or other threats to these vital necessities.
Hydrogen has the potential to address all of the above. And in the process, restore the health and stability of our global environment for future generations.
|Night operation HyERA™ example system model: renewable power is less than demand requiring hydrogen usage and producing potable water|
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.