Request for Information (RFI): Stimulating Geochemical Reactions in the Subsurface for in-situ Generation of Hydrogen and Helium Production | DE FOA 0002786

FAQs: DOE ARPA-E RFI on Subsurface Hydrogen and Helium "Georeactors" (DE-FOA-0002786)

1) What is this opportunity?

This notice is a Department of Energy (DOE) ARPA-E Request for Information (RFI) about a possible future research program. The concept being explored is whether the subsurface can be used as an engineered chemical reactor to generate hydrogen, and potentially helium, with little to no carbon emissions.

2) Is this a grant solicitation or a funding opportunity I can apply to?

No. This is not a grant solicitation and it is not accepting funding applications. ARPA-E is only collecting input to help decide whether to create (and how to shape) a future funding program.

3) What is ARPA-E trying to learn from the RFI?

ARPA-E is seeking technical and programmatic input from researchers, companies, and other stakeholders on whether subsurface environments can be intentionally stimulated to produce hydrogen at meaningful scale and cost, and what breakthroughs would be required to make subsurface chemical synthesis and gas production a credible clean energy pathway.

4) What is the core idea ARPA-E wants to "pressure-test"?

The core hypothesis is that underground environments might be stimulated and managed to drive geochemical reactions that produce hydrogen at a cost aligned with DOE's Hydrogen Shot goal of $1 per kilogram, while also potentially producing helium with little to no carbon emissions.

5) Why does ARPA-E think the subsurface could work like an industrial reactor?

The RFI points to several subsurface characteristics that resemble industrial chemistry conditions, including elevated temperatures common in deep geothermal settings (roughly 175 to 400 degrees F), high pressures that increase predictably with depth (on the order of 10 kPa per meter), and rocks that can contain catalytically relevant metals such as nickel and iron.

6) What pressure and depth ranges does the RFI highlight as relevant?

ARPA-E notes that industrially relevant pressures are reachable at typical drilling depths. As an example, around 400 atmospheres is comparable to pressures found at about 2 km depth, which is within the range of many existing subsurface operations.

7) What subsurface settings are of special interest for hydrogen generation?

The RFI highlights two main contexts: (1) hard rock systems (especially old Precambrian formations) and (2) hydrocarbon-rich basins where hydrogen might be produced from hydrocarbons underground.

8) Why are Precambrian hard rock systems mentioned?

ARPA-E points out that Precambrian formations make up a large fraction of continental crust and can host natural hydrogen-generating processes such as radiolysis and serpentinization.

9) What is radiolysis in the context of this RFI?

Radiolysis is described as a process where radiation from radioactive decay splits water to form hydrogen and oxygen, which can lead to natural hydrogen generation in some hard rock environments.

10) What is serpentinization in the context of this RFI?

Serpentinization is described as a redox reaction where iron-bearing mafic and ultramafic rocks react with water in ways that produce hydrogen.

11) Does the RFI claim we already know how much hydrogen the Earth naturally produces?

No. The RFI references published estimates suggesting natural terrestrial hydrogen seepage could correspond to a wide range (roughly 0.1 to 33 percent of today's global fossil-based hydrogen production), but it also emphasizes that uncertainty in actual production rates is large.

12) What kinds of stimulation or control methods is ARPA-E asking about for hard rock systems?

ARPA-E is looking for information on whether hydrogen-generating reactions could be accelerated or sustained by managing controllable parameters such as water availability, temperature, permeability, reactive surface area, or other factors that might enable the subsurface to function as a practical "georeactor" for clean hydrogen.

13) What is the hydrocarbon-basin idea ARPA-E is exploring?

In hydrocarbon-rich basins, ARPA-E is exploring a hypothesis that hydrogen could be produced by cracking hydrocarbons underground and bringing only hydrogen to the surface, while leaving carbon in place.

14) Why is ARPA-E interested in subsurface hydrogen from hydrocarbons?

The motivation described in the RFI is to avoid the large carbon emissions associated with conventional surface hydrogen production, which today is dominated by steam methane reforming and coal gasification.

15) What emissions numbers does the RFI cite for conventional hydrogen production?

The RFI cites typical emissions intensities of about 9 tons of CO2 per ton of H2 for steam methane reforming and about 19 tons of CO2 per ton of H2 for coal gasification.

16) Does the RFI say subsurface hydrocarbon cracking is proven to work?

No. ARPA-E is explicit that it is not yet clear whether this approach is technically feasible at meaningful scale, whether reaction control and gas separation can be achieved, or whether it can be economically competitive with surface hydrogen production paired with carbon capture and storage.

17) Why does the RFI focus on gas handling and separations?

The envisioned end state involves not only generating hydrogen (and possibly helium) underground, but also collecting and purifying it. The RFI therefore signals interest in advances in subsurface gas handling and separations, including how gases move through porous or fractured media, how to manage competing reactions and byproducts, how to avoid loss mechanisms, and how to selectively produce, extract, and separate hydrogen and helium from other subsurface gases under real field conditions.

18) Is helium part of this concept too?

Yes. The RFI discusses the possibility of producing both hydrogen and helium with little to no carbon emissions, and it highlights the related challenge of separating and producing useful gases at the surface.

19) What agency and program is issuing this RFI?

This is issued by ARPA-E within the U.S. Department of Energy (DOE).

20) What is the Funding Opportunity Number (FON) and CFDA listing?

The notice identifies Funding Opportunity Number DE-FOA-0002786 and CFDA 81.135.

21) Are there any awards, an award ceiling, or an expected number of awards?

No. Because this is an RFI and no funding is being offered through it, the notice states there is no award ceiling and no expected number of awards.

22) Who is eligible to respond to the RFI?

Eligibility is described as unrestricted for providing information, meaning any type of entity may respond, subject to any clarifications in the full RFI text.

23) How were responses requested to be submitted?

Responses were requested as PDFs submitted by email to ARPA-E-RFI@hq.doe.gov.

24) What was the deadline to submit an RFI response?

The deadline listed in the notice was 5:00 p.m. Eastern Time on July 11, 2022.

25) Where were the full RFI text and instructions posted?

The full RFI text and instructions were made available through the ARPA-E funding opportunity website at arpa-e-foa.energy.gov.

26) What should respondents focus on in their input, based on the notice?

Based on the notice, ARPA-E is looking for input on promising technical routes, target formations, the key technical hurdles and enabling breakthroughs (including reaction control and separations), and what development milestones a future program might use to evaluate progress toward credible subsurface hydrogen (and possibly helium) production.