Pennsylvania Legacies #186: Notes From the Underground

Could Pennsylvania’s underground rock formations become a reservoir for captured greenhouse gas emissions? With a newly funded soil sample storage facility on the way, the Pennsylvania Geological Survey is in a better position to find out. We chat with Assistant State Geologist Kristin Carter.

For close to a hundred years, scientists with the Pennsylvania Geological Survey have been collecting rock samples from deep underground. Those samples have been a vital source of information guiding land-use decisions across multiple generations of resource extraction in the Commonwealth. The cores are cylinders of rock that can be anywhere from a few feet to hundreds of feet long, and come from different sources throughout the history of extraction in Pennsylvania. The majority of cores from western and northern Pennsylvania counties were donated by industry, including oil and gas, coal, and quarries. 

Kristin Carter, Assistant State Geologist with DCNR’s Bureau of Geological Survey, estimates that there are around 100,000 linear feet of core in the existing library. The collection has long since outgrown its home at the Survey’s Middletown headquarters, forcing tough decisions about what to keep and where to keep it. Fortunately, DCNR’s budget for this year includes funding for a new facility to house all those core samples, and make the data more accessible to the public.

“There’s been so much interest in terms of drilling. We’ve heard anecdotally about all of the work that various extractive industries have been doing in our state, and every time someone comes to the library manager, he has to weigh in his mind ‘ok, we have no space,’…It will give a way to strategically manage our holdings,” said Carter. 

Why is now the time for Pennsylvania to invest in this new facility? 

There may be potential to sequester billions of tons of carbon dioxide in underground rock formations found in parts of the state. That could be a key piece of the puzzle for Pennsylvania’s efforts to curb greenhouse gas emissions: if there’s going to be a place for natural gas in the net-zero energy and manufacturing sectors of the future, reliable storage will be indispensable. Because a lot of that captured carbon would end up stored under state forests and other public lands, DCNR wants to know more about their capacity, as well as any environmental or safety risks that could arise. 

“You need additional characterization of cap rocks, the rocks that would seal and prevent any injected fluids from moving,” said Carter.  

As the largest landowner in the state, Carter says that DCNR will need use a variety of strategies to meet its climate goals. CCS will likely play a role for the Geological Survey’s contribution. 

“From a Geological Survey component, just knowing the rocks and having a comfort level with reservoirs and how they work, including storage reservoirs, in the success of our natural gas storage fields here in Pennsylvania for almost a century, I have a comfort level with saying that is something that is definitely part of the mix and can be done safely, as long as your site evaluation is thorough and responsible,” she said.

CCS has been a large part of the conversation recently due to Pennsylvania’s multiple bids for federal funding to develop hydrogen hubs, which, according to the Department of Energy, “will create networks of hydrogen producers, consumers, and local connective infrastructure to accelerate the use of hydrogen as a clean energy carrier.”


PEC’s Decarbonization Recommendations

WESA: Pennsylvania boosts carbon capture research with investment in state geological survey

Josh Raulerson (01:33):

Starting off, just by way of background, could you tell us a little bit about Pennsylvania Geological Survey, your mission, your activities?

Kristin Carter (01:40):

Yes, of course. So in Pennsylvania, the State Geological Survey is a bureau within our Department of Conservation and Natural Resources. And over the centuries there’s been four geologic surveys. So we are considered the fourth survey. We were established in 1919, and so we, we just a few years back celebrated our a hundred year anniversary. Our mission is to characterize and disseminate information on the Commonwealth’s geologic natural resources. Those are varied and many, everything from fossil fuel based non-renewable stuff to industrial minerals and groundwater geohazard. All of those, those things that make the Pennsylvania landscape what it is, and sometimes provide, you know, challenges and hurdles for us as well. So we provide the, the scientific research to understand those things and help inform policy and business decisions around the use of the Commonwealth’s resources.

Josh Raulerson (03:00):

Okay. So an agency with a, with a long history, as you said — how long has the geological survey been collecting core samples from underground and, and why? What’s the purpose of that?

Kristin Carter (03:09):

Yes. So core samples that we have in our rock sample library in our Harrisburg area headquarters of Middletown, PA come from different sources. By and large, the majority of the ones from Western Pennsylvania and even the Northern Tier counties. So from rocks associated with the sedimentary layers of rocks in the Appalachian Basin, those are coming from industry donations. So whether they’re oil and gas exploration companies or coal mining entities or quarrying efforts that, you know, they, they need some subsurface support to what they’re seeing at ground level. They will collect those things and then donate them to us e eventually. So we serve as a, you know, an archive for that type of sample and information. You know, I’ve been with the survey since 2001, but as I understand it, core samples date back to probably the mid 20th century or thereabouts, you know first with, you know, mining donations.

And then, you know, more recently with the oil, gas and shale gas development that we’ve, we’ve seen, there is also, you know, survey-specific projects, mapping projects where we are granted some money to collect our own rock cores. So the, the field maps who are describing the lay of the land, at ground surface, they want to inform the interpretations of what they’re seeing with shallow subsurface rock information as well. So oftentimes our mapping efforts, at least in the last 10-15 years, they tend to be tied with some shallow cores funded from, you know, federal entities and the like. So the library takes all of that stuff in. We also have accepted what are called rock cuttings so that the ground up bits of rock from air drilling through the subsurface, where you’re just grinding it, you’re not, you’re not collecting a whole core, you’re just, you know drilling down through those materials and the air return brings those cuttings back to surface. To the extent those are donated, we have those two and we use those to inform, you know, what are the properties of those rocks. Depending on the, the, the age type and disposition of the sample, you can determine the mineral. So the, the bulk composition of, of the material, of the geologic material, as well as important stuff like porosity characteristics. And that will come, comes into play with carbon storage because it’s a pore space that you, you know, put the CO2 into and permeability, et cetera, et cetera.

Josh Raulerson (06:07):

And help me visualize a little bit, what does a core sample look like? How much space does it take up and how much space is this library currently taking up? The existing facility?

Kristin Carter (06:18):

Yes. So currently our library in terms of core samples, cores are going to be cylindrical pieces of rock that can be, you know, a few feet long to thousands of feet long depending on how much an operator collects at a, a particular well location or a boring location. Coal cores tend to be smaller diameter, so maybe a couple inches or less. Some of the older oil and gas core that we have is larger diameter, so maybe four or even closer to what looks like six inches, you know, in diameter and the wider the diameter the heavier it is. We have, I want to say somewhere along the lines of a hundred thousand linear, linear feet of core in the existing library in Middletown right now that doesn’t account for the, the rock samples that I mentioned. So we count those like by boxes. So you’ve got tens of thousands of boxes of, you know, rock cutting, so sample envelopes that get put in rectangular boxes for archival. And I would say, you know, if you want to visualize a footprint, the current rock sample library is the basement of our headquarters, which is a free standing building. It’s got high ceiling. So we’ve got a, a forklift that’ll, you know, move stuff around the shelves, go from floor to ceiling.

Josh Raulerson (07:47):

So, I mean, with just the volume of material accumulated over the years, you’re due for a storage upgrade. Are there other reasons why now is a particularly significant time for this investment to be made?

Kristin Carter (08:00):

Yes, this is something that you know, many of the, the survey staff and not just myself have been advocating for, for some time because there’s been so much interest in, in terms of drilling. And we’ve heard, you know, anecdotally about all the work that various extractive industries have been doing in our state. And every time somebody comes to the library custodian, the library manager, he has to weigh in his mind, okay, we have no space, but yet this is coming in and it’s deeper depths than we had before. So we have to accept that. And, and if he accepts that, then we can’t retain maybe shallower core samples from different sites in different parts of the state. So, I mean, it, it really is a balancing act and, you know, when you can’t keep everything and when we still you know, the need to expand, have a new location and, and all that, that, that’s not going to allow us to just take everything and anything that’s offered to us in the future. But it will give a way to strategically manage our holdings. So more working room, more visitor room for viewing sampling core. And then, you know, as we will still from time to time have to do some purges, you know as we eventually fill whatever the new facility might look like up to, you know, keep our, our efforts going.

Josh Raulerson (09:37):

One thing I want look at is what’s driving the collection of samples in the first place. And in particular, as you know, right now, the state, the Commonwealth and the Department of Conservation of Natural Resources is taking a close look at carbon capture and storage. What reason do we have to think that there might be potential for carbon sequestration, you know, under the ground in Pennsylvania? What’s unique about Pennsylvania’s geology that makes it interesting from that standpoint?

Kristin Carter (10:05):

There’s an old adage that the oil and gas industry has that if a reservoir can make it, it can take it. And Pennsylvania has been producing oil and gas since Drake’s well, you know, struck oil in August of 1859. Certainly that was a shallow well but over the years, over the decades as technology increased and as the need for, you know, domestic heating and power and, you know, use of fossil fuels to, you know, fuel our world the industry has drilled more extensively in Pennsylvania, and deeper, over time. And it continued to find oil and gas in different layers of rocks. So, by way of example, the Oriskany Sandstone, it’s  a rock unit that depending on where you’re at in the state may be, I don’t know, a few thousand feet deep to more than a mile deep in the subsurface.

Kristin Carter (11:11):

It’s been drilled for natural gas since 1930. So it’s been productive for almost a, a century. Many of those rocks those a risky fields have since been depleted of their gas and have been converted to natural gas storage by utility companies. So here, natural gas, I’m talking about methane. So the, you know, the gas that powers a lot of, you know, our stoves and, you know, a lot of consumer applications, that conversion of production to storage, at least in a temporary way, a seasonal way of natural gas storage has been going on here in Pennsylvania since the late 1930s. And by extension, the prospect of carbon storage or, or any other energy type storage, hydrogen or anything else, we, we invent or, you know, discover in the future is going to have a need and can, can be similarly performed. Now, depending on the, the fluid in this case, CO2 and the fact that we’re talking about permanent storage and not just the seasonal in-out kind of thing, like the utilities need for their, their applications, you need additional characterization of caprock.

Kristin Carter (12:28):

So the, the ceiling the rocks that would seal and prevent any injected fluids from moving out of zone or out of the reservoir, the, the target formation, whatever you want to call it. So, coming back to the need for core and rock samples from the subsurface, that is a very important part of the buildout of, of any type of carbon management hubs, hydrogen hubs, carbon storage projects in Pennsylvania and the surrounding, you know, in our surrounding states. So if you don’t have a publicly available source of those rocks, and it, it, it’s not, it’s not going to be perfect, it’s not going to include every formation that everybody’s going to be interested in, but to the extent that we have it in our archive, it should be publicly available to everybody. So that’s, you know, part of the impetus for this new facility and why it’s tied to the, the topic of, of CCUS, because it’s not just about knowing how the wells that tap these different geologic formations produce or can be injected into. You need to characterize some additional parameters to ensure that carbon storage is going to be good for an area or not, you know, safe or not. So that’s the the next step we want to take and, and be able to provide that as a service for folks.

Josh Raulerson (13:54):

You mentioned safety. Could you elaborate a little bit: what are the potential risks that we might want to know about and and how can this kind of research help us better understand those?

Kristin Carter (14:04):

Yes, so CO2 is an asphyxiant. So I mean, like, you know, if, if we were in a room with just CO2, we wouldn’t be able to breathe, you know, so any mass release of CO2 from a tank from the ground or wherever it’s being contained or stored poses that health risk. So if you’re going to gather and inject CO2 into the subsurface, you want to make sure that the target rock that you’re putting the, the CO2 in is going to stay in place. You know, whether through physical means or chemical, you know, any type of interaction with the rock, the physics of, you know, subsurface pressures, et cetera, et cetera. So some of the, the risks associated with injecting CO2 is, first of all, are the rocks that you want to put that material in? Can they take the pressures that you need to inject the CO2 at?

Because you don’t want to over-pressure the, the subsurface formations because then you run the risk of fracturing them, you know, breaking up the rock and then the CO2 is going to migrate out of zone and eventually come back up the surface and there would be a release. So that’s one risk, you know, over pressuring the reservoir during operations, say you get your CO2 into your containment reservoir and you’re, you know, continuing to add CO2 or maybe you’ve completed your project and it’s underground to the extent that there might be what I’ll call you know, legacy geohazard. So, you know, unknown older wells that were not sufficiently identified, plugged and abandoned could serve as a conduit for, you know, migration of CO2 out of zone and eventually to ground surface. If for some reason industry was going to, some extractive industry was going to come along and work in that area, and perhaps they breach the storage zone through their activities, for example, shale gas.

That would be another thing where the presence of that, the fracking of a new shale gas, well, that could cause loss of containment and migration out of zone to, to ground level. So any subsurface activity, historical, you know, whether or not we know about it to current day, those are the kind of risks that any carbon storage project is going to have to work on and demonstrate that they’re, they have plans for addressing. But what’s more, I think at the state level, we have to be able to coordinate the use of those subsurface reservoirs, just like the DEP regulates, the, the mining and oil and gas industries here in southwestern PA where I am, people have legal right to develop coal resources as well as oil and gas. So there’s a coordination effort that’s required and, you know, the industry has to comply with. So I see a similar, you know, but more extensive responsibility there with carbon storage prospects.

Josh Raulerson (17:09):

And, you know, it’s my understanding too that just due to the complexity — engineering complexity, which you kind of just described, and legal complexity as well — that in practical terms, if carbon capture happens — storage, rather — happens at scale in Pennsylvania, a lot of it’s going to be on public lands, state owned lands, simply because those are the largest pieces of land available. So I’m, I guess I’m wondering: where does the work you’re doing and the research and the data you’re collecting, how does that inform decision making about things like whether to, you know, to issue a, a lease or permit?

Kristin Carter (17:45):

Yes, that’s a great question because we, you know, knowing that DCNR or the Commonwealth is like the major, the biggest landowner owner in the Commonwealth we’ve got a lot of state lands, state forests you know, it’s more than a couple million acres. So over the last few years, DCNR as well as DEP and members of DCED community economic development, we’ve been meeting routinely as part of a interagency work group to facilitate CCUS considerations like this. So our geology folks have provided information, for example, to our Bureau of Forestry folks, and they maintain right now, and they have to oversee the, the leases around extractive efforts. So the production of gas on, on state lands, for example, when they do, when DCNR does not own that subsurface and somebody else does and is developing it, we provide information on the, the sequestration reservoirs, the potential reservoirs in terms of the reservoir parameters, you know, depth, thickness extent trapping mechanisms, permeability to the extent we have that they know how much the reservoirs have produced over time.

So that gives you a feel for perhaps how much those reservoirs might take. But, you know, we stand at the ready to, you know, advise them on getting out in front of this, this concept of, okay, well the state’s a big landowner, if we’re deemed as pore space owners because of that, what is our policy going to be? And those conversations are going on right now,

Josh Raulerson (19:25):

And those conversations are really deeply enmeshed with sort of larger energy policy conversations. Can you speak at all to the role of carbon capture in meeting Pennsylvania’s climate goals? What is the real greenhouse gas emission reduction impact of carbon capture, potentially, in Pennsylvania?

Kristin Carter (19:43):

Yes. So as an agency DCNR understands that climate change mitigation is going to take multiple technical approaches as part of a, you know, portfolio of ways to reduce and eliminate CO2 emissions now and into the future. The CCUS, you know, the, the carbon storage component of that, you know, might account for anywhere from, you know, 10 to 20% of the way in, you know, which we need to reduce our emissions to, to become neutral. But that’s not to say that fuel switching use of renewables efficiencies, all of those things are needed as well. So, so some of those approaches are what other bureaus within the agency have spearheaded and, and already implemented at our state park facilities, you know, using solar energy on sites, working to improve our fleet with better vehicles and using renewables.

So I think it’s fair to say that although from an agency perspective, each and every one of us that works for DCNR might see these various technical solutions as more or less part of the overall, you know, impact of, or the need for climate change mitigation. We all agree it’s an “everybody in the pool” type approach. From a geologic survey component, just knowing the rocks and having that comfort level with reservoirs and how they work including storage reservoirs and the success of our natural gas storage fields here in Pennsylvania for almost a century. I have a comfort level with, you know, saying that is something that is definitely part of the mix and can be done safely as long as your expectations are reasonable and your site workup, your, your site evaluation is, is thorough and responsible.

Josh Raulerson (21:47):

I’m wondering about like the, the potential economic impact of large scale storage happening in Pennsylvania. Both in terms of what’s needed for, again, the sort of larger clean energy policy and manufacturing coming online in order for it to, you know, be sustainable, CCUS arguably has to be part of the picture. But looking beyond that in terms of, I suppose, job creation, just broader economic activity, can carbon capture and storage be an industry in Pennsylvania in its own right?

Kristin Carter (22:19):

Yes. the, that’s the short answer. The long answer, I think, I could go a couple ways with that. The first way would be to say that carbon capture and storage as a service, you know, some states are looking at this technology as a way to say, you know, we’re going to prove out these resources in the subsurface, and it could be a private sector entity, it could be a public sector entity. This is our storage facility. Send us your CO2, and you know, you pay us to, to sequester it for you. That that’s one way, that’s one mechanism. But not even looking at it that way, another way to go with the answer would be to say that certainly all of the technical and trade staffing and, and expertise, you know, that we have here now due to the oil and gas industry and some of our other extractive industries and products like cement and ethanol, et cetera, those jobs can be expanded and would, would need to be expanded and, and added to because the gathering and transport infrastructure that are going to be needed for carbon storage here in our region, even if CO2 is, is not necessarily stored, you know, where it’s, where the emissions is taking place, the CO2 would be put in a transmission line that would go somewhere else. And so you’re going to need all the good trades people to build that infrastructure to maintain that infrastructure. You’re going to need the technical expertise to, you know, plan and build out that part all of the above ground or near, near surface support infrastructure, apart from the, the storage reservoirs themselves.

Josh Raulerson (24:02):

Maybe be another way of coming at it, too, is that, you know, there have been very big public commitments made by corporations and others that carbon capture is part of their plans. It’s coming to Pennsylvania in some form or another. If the storage piece doesn’t pan out kind of as you suggested, where does that carbon go? We put it in a pipeline and send it where?

Kristin Carter (24:23):

Yes. So the, the state or the survey we were involved in a, in a project a few years ago that evaluated in a desktop way because we were not permitted to gather new drilling or seismic or, you know, do any new testing per se of the mid-Atlantic offshore. So there are several thousand feet of sedimentary rocks in, in the Atlantic Ocean to our east that do have a certain amount of prospect for serving as storage reservoirs. So I know that some in the private sector and public sector even now are considering how do you make that work? Because it, it would require interstate pipelines and collaboration, not just moving across Pennsylvania. We’d be talking Maryland and likely New Jersey, Delaware, New York even. And so that’s one thing that, that I’ve heard talk of and that we’ve been involved with, you know, at least the science behind it. And it does look perspective to me. The other would be just by virtue of the amount of industry in the Ohio River Valley, you will also see transportation infrastructure to point south and west with respect to, to CO2 pipelines as well. And don’t discount the opportunity that CO2 may provide as like a feedstock, as a beneficial use product, to many of those industries in that region too. So it’s not just once it’s in pipeline, it’s going to stay there. It may be distributed to entities for their business uses.

Josh Raulerson (26:07):

So that’s the “U” in “CCUS.”

Kristin Carter:

Yes. Yeah.

Josh Raulerson:

Coming back to the work that the survey is doing and, and the research, what don’t we know that we need to know? When will we have a better sense of whether Pennsylvania is suitable for carbon storage — both, you know, geologically feasible, economically viable, and what have you?

Kristin Carter (26:25):

Yes, so generally speaking, I mean, I would summarize by saying that we know the most about our rocks in the first mile of subsurface. And the reason for that is because at least where you and I are sitting today, the depth of the Marcellus Shale is roughly a mile beneath our feet. By and large, you know, the majority of the 275 plus thousand wells that have been drilled here in the state are completed somewhere in that first mile of subsurface. The second mile, we have a decent amount of information because we’ve had development of certain reservoirs, you know, over the decades, like the Oriskany, like the Medina Group sandstones, and we can make inferences about how good they are based on the oil and gas production activity that we’ve seen. What we know the least about is that third, third plus mile. So the deepest parts of the basin, which are probably in Pennsylvania and parts of West Virginia, it associated with a deep structure called the Rome trough.

That third plus mile of sedimentary rock package is what we know very little about because there has not been industry exploration or otherwise, somebody paying for, you know, test wells in those parts of our states. So to the extent that carbon storage projects being proposed here in Pennsylvania, have a volume requirement, you know, like a annual, I’ve gotta sequester 2 million metric tons or 3 million metric tons a CO2 every year, they’re probably going to have to characterize that third plus mile if they’re near it before they decide that we can’t sequester on site. We have to rely on a pipeline buildout that has yet to happen. That’s the critical piece. The deepest parts of the subsurface federally funded or federally offered programs like Carbon Safe could be options for companies that need or want to do that to characterize their, their subsurface geology under their site.

And there’s some funding opportunities out now from DOE for carbon capture and transport technology as well as states and including state surveys that will add to the knowledge base. And for Pennsylvania, I can say that we are working on proposals or are part of proposed efforts through those funding mechanisms. Now the deadlines for those things are coming up in anywhere from February to April, and the April deadline that I’m thinking of that’s related to the, the hydrogen hub program that DOE is offering. I wanted to mention that too. I, while the survey is not a project partner per se in this, we do know that there are two hydrogen hub applications that submitted concept papers to DOE and we’re encouraged to submit full applications. So one’s associated with Western PA and Shell and Equinor are the, the key technical folks. The other one is in southeastern PA in the Philadelphia area, presumably related to the, you know, all of the industrial work in fluids and air products and, you know, activity in and around the, the harbor area there.

Josh Raulerson (29:48):

Actually, could you elaborate a little bit on why carbon capture and storage is such an important part of the equation for the hydrogen hub scenario, the difference between blue and and green hydrogen and, and how CCS fits in there?

Kristin Carter (30:00):

Yeah, so the coloration of these opportunities, I think began as a way to, you know, explain to lay folks the differences in how hydrogen energy might be developed and or what its ultimate carbon footprint would be. But we’re so far past the blue and green thing now that I think it’s confusing the mass public more than clarifying things. So thanks for the opportunity to at least tell you more about what blue and green are, because those do relate to our region, the hydrogen hubs applications that many folks, many entities are working on right now. You have to propose that you’re going to produce hydrogen energy through renewable means, so perhaps through the electrolysis of water. So you’re taking the hydrogen molecules out of the water, essentially and you’re using some kind of renewable energy resource to fuel that process. Most commonly, nuclear is what we read about in that scenario.

You’re going to end up with a green hydrogen energy product because you did not use any fossil fuel or non-renewable energy resources to make your hydrogen in our region. You know, Pennsylvania is such a big, you know, literally and figuratively part of the Appalachian basin, and, and that’s why we’ve been developing oil and gas since 1859. Our rocks have those hydro, those non-renewable resources in them, and the shale plays that have been developed in the last 15 years and continue to be developed now are just demonstrating that this basin has so much gas to offer. So domestic energy resources, the creation of blue hydrogen is when you use natural gas as your feed stock, and you take the hydrogen from your methane, and that’s going to generate carbon dioxide in the process. So hydrogen hubs, if they’re truly dedicated to having little to no carbon footprint, you know, being environmentally responsible, you’re going to make hydrogen from your natural gas, but you’re going to grab that CO2 at the emissions point at the stack, and then you’re going to sequester it so that there’s no net emission of greenhouse gases. So that’s the difference. And, and unlike different parts of the country, you know, other parts of the country, our part of the country hydrogen hub is I think, necessarily going to have to be a blue hydrogen type scenario because of all the natural gas resources that we offer that other parts of the US do not have.

Josh Raulerson (32:41):

So the blue/green dichotomy is a little bit misleading because, and tell me if I’ve got this right, because really the, the key thing we should be looking at is the total carbon footprint, the, the impact of the production of the hydrogen as long, like you can make it theoretically with natural gas, contain it, sequester it, and you’re good. It’s still, it’s a zero carbon energy source. Is that approximately right?

Kristin Carter:

Approximately right. Yes. Yes. You got it.

Josh Raulerson:

I’ll take it. That’s that’s about as right as I can ever hope to be on these things. But I appreciate the expertise and the insight, this has been a really informative and interesting conversation.

Kristin Carter:

You’re welcome. I appreciate it.