cc >> Cassie Immel: Good evening.
Thank you for watching tonight's Wednesday Nite at the Lab.
I'm Cassie Immel from here at the Biotech Center.
For tonight's presentation, Dr. Dave Hart presents
"Tapping Geothermal Resources in Wisconsin: Energy from
the Earth for Heating and Cooling our Homes."
Dr. Dave Hart is a professor in the Department of Environmental
Sciences in the University of Wisconsin Extension in
hydrogeologists and geophysicists for the Wisconsin
Geological and Natural History Survey.
His current research and interests include measurement of
the hydraulic properties of midcontinental rift sediments to
determine their suitability for carbon sequestration, the
hydrogeology of the Cedarburg bog in eastern Wisconsin, and
the connectedness of sand bodies within the lakes of the Glacial
Lake Oshkosh. He is also interested in
developing web applications to allow citizen input of Wisconsin
features and provide information on sites of geologic interest in
Wisconsin. He received his BA from Luther
College in Iowa and his PhD from here at the UW.
Please help me in welcoming Dr. Dave Hart.
[APPLAUSE] >> Dave Hart: Thank you, Cassie.
Thanks for your applause here. I hope to, tonight, give you a
tour of geothermal resources in Wisconsin, and I changed the
title a little bit from the less colorful one that I sent Tom.
And so geothermal, is it hot as Hades?
Does that mean is it a resource that's viable for Wisconsin or
is it the frozen tundra and maybe we should put our energy
into different energy resources. So that's kind of the question
I'm asking. That's kind of framework for
tonight's talk. I'm Dave Hart with the Wisconsin
Geological and Natural History Survey.
I want to acknowledge two collaborators/co-workers.
One is James Tinjum, and the other Dante Fratta.
They're both kind of kitty-corner here in the
Department of Engineering in the Geological Engineering
Department there. I'd also like to acknowledge the
Department of Energy. They kind of got me funded and
interested in geothermal in Wisconsin.
They provided a grant to the American Association of State
Geologists. Wisconsin's state geologist came
to me and said, Dave, I strongly urge you to look at geothermal
in Wisconsin, and when the director, the state geologist
asks me to do things and strongly urges me to do them, I
generally follow his lead. But I think there's a lot of
good things that are going to come out of this research here.
Also, the Wisconsin Water and Well Systems, we're going to
collaborate with this driller on some research hopefully.
And then two engineers from Affiliated Engineers Inc.,
they provided some of the slides that I'll be showing you
tonight and some of the information.
So geothermal energy is not new. We've been using this for
centuries, in fact. Here's one of those places I'd
like to get to eventually: the Roman baths at Bath in England.
Here's the great bath. This is the Roman part and then
they added this later on. This is, I think, from second
century AD or so. And then here's the original
spring that kind of bubbled up. It was a sacred spring, then the
king took over and made it his bath.
So we had rainwater fall on these nearby hills.
It percolates downward almost two miles or so, or so they
estimate. Picks up heat and comes to the
surface. Now, it's not exactly hot.
It's only 115 degrees, Fahrenheit, not Celsius, but I
imagine if you're in England, 115 degrees may feel kind of
nice on some of those foggy, cold day.
Just another example of geothermal, if you found an
archeologist that could do a whole presentation on this.
The hot springs at Thermopylae which translates as hot gates
where you could, I suppose, go see Hades and his dog there.
This is very close to where the Persians met their demise by the
Spartans too. But I guess it was a swamp at
that time and smelled like sulfur, and they kind of ditched
it and turned it into a tourist area now.
Another slide, this is, you've probably seen this, this troop
of monkeys discovered in the late '60s that these hot springs
in Japan were kind of nice places to go hang out.
So it's not just humans that like to go hang out in a hot
springs; some other species have figured this out as well.
All right, I'm going to take you now through kind of the
research, our understanding of, it's really kind of a history of
the Earth and it kind of tracks the way we think about science.
And I know you guys see a lot of science talks so we'll kind of
go with that. Some of the early research,
Robert Boyle, Boyle's Gas Law, you may have heard of that from
high school. And he, in 1738, states in one
of his books: "Provided a man descends low enough into the
bowels of the Earth, he will find it very hot."
And he wasn't just speaking from a religious perspective, he
knew this, which it's not just the Christian tradition that
thinks it gets hot. There are other traditions but
there are others that believe it gets cold, so that may or may
not be founded on geothermal energy, those traditions.
But this was an observation here too.
Then we have an Englishman, Robert Were Fox the Younger, in
1820, in a report to the Royal Geological Society of Cornwall,
and here's that. We have it on the temperature of
mines. So he noticed that these mines
were getting hot and in 1820 makes his report to the Royal
Society, Geological Society, that there is a progressive
increase of temperature in descending from the surface to
the greatest depths hitherto examined.
And he now begs to submit the result of further inquiries to
this society. And his results, and so here I
think is really the first example where someone has
calculated, put a number on, people have noticed it gets warm
when you go down. Here we've got somebody who's
calculated how warm it gets with depth.
And so he looks at Professor Meyer's tables, finds the
surface temperature is 53 degrees Fahrenheit, and finds
out as he goes down in the mine it gets 6 degrees warmer for
every 300 feet. And if we look at the
temperature increase with depth, I'll just divide it, that means
two degrees per hundred feet of depth you get a warm up two
degrees. And that's a pretty decent
number. We see numbers like that around
Wisconsin, as I'll show later. And if you want to do a little
math, you start at 50 degrees and you go 5,000 feet, about a
mile down, you can do 5,000 times 2, divided by 100.
So we have 10,000 divided by 100 gets us to 100 degrees.
So at a mile, we'd be at 150 degrees.
Two miles, 250 degrees. And so right there that's
kind of a powerful thing. We'd know if we brought that
water up to the surface, if we could get it from two miles
down, it would boil at the surface.
It would be that hot. And so maybe we could use that
to run turbines or something. Some more early research kind of
just tracking along. In 1867, the British Association
for the Advancement of Science formed a committee.
And the purpose of this committee was to investigate the
rate of increase of underground temperatures downward in various
localities of dry land and underwater.
And I've captured the capitalization that they used at
that time. I'm not sure of the rules they
used, but it must be for emphasis.
And what they're looking for there is they're trying to
understand, they're looking at working conditions in mines.
They're finally making the mines deep enough that it's getting a
little bit hot for the workers to work down there.
We have this impression you go in a cave and it's 50 degrees.
Well, that's because we're not going down very deep.
If we keep going down, it's going to start to become
uncomfortable. We could use that number that
Robert Fox calculated earlier, and we could go, yeah, we go
down a thousand feet, it's going to get pretty uncomfortable.
We're not going to want to be there.
And so this committee wanted to understand how things were
changing. And so they started to do
temperature measurements in wells.
And so you can imagine, if you have a deep well and you have a
thermometer, just a regular mercury thermometer, and it
takes you five minutes to lower it to the bottom of your well,
you have to pull it back up, you're not going to get the
right temperature. So this committee also drove
some science. It drove the maximum temperature
thermometer, and that's a kind of, for those of us who are a
little bit older, you'd get the thermometer in your mouth and
you'd have to shake it? That was a maximum temperature
thermometer. And that was actually, it seems
to me, invented by a German, I can't recall his name, to make
these measurements. He would lower it down in the
well, and then he could pull it up.
He didn't have to pull it up really quickly to try to get the
measurement. So this actually drove some
technology. And so the idea here is you have
a well and you just take a series of measurements of depth
and then we can look at how the temperature here increases with
depth, and we can just see it going up and up and up and up.
And that would be the two degrees per hundred foot or so
that we saw earlier. And then we have Alexander
Stewart Herschel still moving forward in time.
He was the grandson of the astronomer, the Herschel who
made all of the telescopes and discovered all of the galaxies.
And what he did, this grandson of the astronomer, was he
measured how well the rocks conduct heat.
He develop an apparatus to measure, some rocks are going to
conduct heat better than others, and let's put a number on how
well it conducts heat. And so we can actually get heat
flow, if we know the temperature change with depth and we get
this thermal conductivity, we can now calculate heat.
Any large temperature change, more heat flow.
That makes sense. Larger conductivity, more heat
flow. That makes sense.
This law just kind of makes sense.
And then also, I think this GA Labour was his laboratory
helper, and apparently if he had patented one-hundredth of the
inventions or improvements he was constantly making or
contriving for others, he would have been a rich man indeed.
So he just cared about his science.
He just wanted to do his science.
And here's his apparatus. You have a sample here.
He had steam come in one end. He had water come in around the
other. And so you have hot and cold,
and then you've got heat flow. And then, as this water went
around the sampler bar, it picked up the heat and because
he knew how much heat it took to raise water one-degree Celsius,
he could figure out how much heat is coming out the other
side because he could measure the temperature being picked up
by this coil here and then he could measure the conductivity
of his rock. And now we're ready
for Lord Kelvin. And I'm a geologist not a
physicist, and geologists love to remind physicists
that Lord Kelvin was wrong about the age of the Earth.
And he was telling all the geologists, you guys don't know
math, you guys are challenged, and the geologists were like,
no, no, the ocean's too salty, we have too much erosion, how
did these rocks get here in the time we want, but Lord Kelvin
did some calculations using those gradients that were
measured by the committee, using the conductivities measured by
Herschel, we can calculate the average heat flow.
And if we do that, we get about, or they did that and they got a
pretty good number. 68 milliwatts per meter squared.
So like this by that by that. You're going to get
68 milliwatts. So if we have a thousand square
meters, we're going to get 68 watts.
And so he's going to use this to calculate the age of the Earth.
And so the idea is the Earth starts off molten, super hot, at
some hot temperature you have a really high heat flow, and at
later times the heat flow is going to decrease.
And so if we plug in that number, 68.4, on this curve,
so here's heat flow as a function of time, we plug in
this and then he says, ah-ha, the Earth is around
100 million years old. And he has a nice estimate for
the age of the Earth. And RJ Lilly has a nice book out
where he says basically what was done was they assumed the Earth
was a hot potato. So you take your potato out of
the oven. In about five minutes it's too
hot to touch. You let it cool.
After about 15 minutes and it's a nice temperature.
Here's the Earth just out of the oven.
It's cooling and then you can calculate the temperature after
a hundred million years. And so that's what was done to
calculate the Earth. However, we know now that
the Earth is about 4.5 billion years old, and what was missing
was the heat of radioactive decay.
And there are three radioactive elements that are in the crust.
You'll find them in most every rock in low quantities.
Some rocks more than others. Potassium, uranium, and thorium.
And they've been around since the Earth formed.
They're still around today. And you can see some rocks have
more potassium, uranium, and thorium than others.
For instance, granite and rhyolites, granite's a pretty
common rock, have about 2.95 microwatts per cubic meter.
So this by this by this is going to produce three microwatts.
That's not much. You need a huge, huge volume if
you want to even get a watt. A football field by a hundred
meters is going to maybe get you several watts, maybe 10 watts of
this being produced. And so that's in the upper
continental crust. Basalt and gabbro, which is a
rock that we find in the oceanic crust, this would be the rock
that you see erupting in Hawaii. That only would give you half a
microwatt per cubic meter. And in peridotite, which is all
this rock is going to make up most of the mantel here, has
hardly any but there's a lot of it.
And so here's the numbers that you come up with.
And so Lilly says you're actually more like a hot potato
in the microwave. It's getting heat heated from
the inside by that radioactive decay, and there's heat
conducting outward. And so then in that way we have
our heat flow working with what we know about the age of the
Earth. So the heat that we see, the
geothermal increase with depth is a function of the
radioactivity in the crust from potassium, uranium, and thorium
and the heat flow from heat of formation when the Earth first
formed. Both of those things are working
together to give us that heat flow.
And here's just a present day measurement of what we see in
the continental US. Blue is 25 milliwatts per square
meter, and red is 100 milliwatts per square meter.
And you can see we've got lots more red out in this part.
The reddest part, or just about the reddest part, is
Yellowstone. That's sitting over a hotspot, a
lot like Hawaii where things are really coming up there.
And then you can see over here in Wisconsin, we're kind of cold
and green here. So maybe we are the frozen
tundra. We'll get back to this map
later. I have a few quibbles with this
map, and we'll get back to it. But you can see, moving to the
east, it's cooler; the west is warmer.
All right, now I'm going to switch into more talking
about the technology. More talking about our energy
use, talking about our technology.
And this, Jim Tinjum put this in a talk, I couldn't resist it,
and it's what if it's a big hoax and we create a better world for
nothing. You can also take the other side
of that and say maybe we want to make sure what we're doing is
actually a step forward and not a step backward.
But anyway, I like that cartoon. Here's our energy consumption by
sector in 2009, and the two things that geothermal can
probably speak to, the two sectors are the commercial,
heating and cooling commercial buildings, and heating and
cooling our homes, our residential.
So that's about 45% to half of our energy needs are those
two sectors. Maybe geothermal can be part of
that heating and cooling. I should also point out that
here in Wisconsin we import all of our energy except that which
we make through the power plants.
The uranium is maybe not the biggest part of the nuclear
power plants. But we import almost all of our
energy, and so anything we can do to be more energy efficient
means more dollars that stay in Wisconsin.
So I think there's a good economic reason to take some of
this energy discussion to heart. Here's our electrical energy
sources in 2009. You can see a large part of how
we generate electricity is through coal.
Some natural gas, that would be, I'm drawing a blank.
They just put in the new, thank you, that would be the
Co-Gen plant here on campus. But the coal would be probably
doing most of the work here in Madison.
Nuclear accounts for 20%. Hydroelectric a little bit, and
then renewables also just a little bit.
And that would include the geothermal.
Here's energy use closer to home.
In fact, it is my home. And we can see last year I spent
$1,600 on electricity and gas. And when I went and looked on
MG&E for a house my size, this is typical, maybe a little bit
low. But we spend a fair amount of
our dollars on heating and cooling our homes, running our
appliances. It's not an inconsequential
cost. Here's US energy consumption by
energy source. Fossil fuels are 83% of our
current energy sources. Renewable energy is 7%.
A lot of that is biomass. So that's things like ethanol,
wood burning, maybe the corn burning.
Geothermal is a tiny little piece of that right now.
Hydroelectric is larger. Solar and wind.
Where's nuclear? There's nuclear and that's about
8% as well too. One thing that, there's no free
lunch in nature. Nature always, we like to say in
geology that Mother Nature always gets to bat last.
And kind of a corollary of that is all energy sources have
impacts. Whether or not it's oil spills,
whether or not it's people not wanting to have their horizon
cluttered with windmills, whether or not it's the
manufacturing process of photovoltaics, all energy
sources have impacts, and we need to take that into account.
We need to understand those impacts and really be careful
about, think about them and take them into account when we're
developing them. And some are going to have worse
impacts than others. Some are going to have impacts
that are farther away, not in my backyard, or in my backyard.
So those are all things to consider.
US renewable energy technologies, you can see
biomass has grown quite a bit. That's probably a lot of that's
ethanol. Wind has really taken off.
Geothermal has held pretty constant in the last decade and
a half. Solar as well.
So when we look at sustainable energy, we can look at energy
conservation with heat pumps or we can look at creating an
energy with the geothermal. Now we're going to go to the,
I've kind of split geothermal into five different types.
The heat pump; the ground source or geoexchange; enhanced
geothermal systems, also known as hot, dry rocks; direct use,
you just take the hot water out of the ground and then you use
it to heat your buildings, you don't do anything to it, you
just pump it around; hydrothermal used to generate
electricity; and then co-produced fluids, hot water
produced during petroleum extraction to generate
electricity. So co-produced fluids, if you
remember on the map of heat flow in the US, if you look down in
Texas and Louisiana, Arkansas, they had a little bit of red and
orange to it. A lot of that corresponds to the
oil fields. And when they produce oil, I
think it's like one barrel of oil you get 10 gallons of water.
That water is warm, and perhaps you can use, it's a byproduct.
They don't want it. What are they going to do with
it? They re-inject it lots of times,
but it might be hot enough to generate electricity.
It's maybe not going to drive a turbine, but you can maybe use
it with a binary cycle generator where you pump it up, you heat
exchange it with some fluid that has a lower boiling point than
water, and rather than just injecting this hot, briny, not
very useful water back into the ground, we can create
electricity with it. And the DOE has some pileup
projects going with that. Hydrothermal, this has been in
use for a long time. First used in Italy 1904.
Geysers in California, the plant, here's some of the
cooling towers in geysers. Generates 725 megawatts.
And just so comparison, MG&E down on Blount Street generates
190 megawatts, those big coal-fired plants down there.
And so this you just take the hot water out of the steam out
of the ground, runs a turbine and then you reinject it.
So a really nice, simple way to go.
You have to be careful because you don't want to pull out too
much water and inject too much cold water.
You can kind of kill off your fuel by sucking the heat up too
fast. So they need to be managed.
And then also direct use. This is hot water.
You just pump it into your buildings.
If you live in one of those parts of the US where things are
red, you can probably heat a building.
The Idaho state capitol is heated this way.
A lot of the buildings in downtown Boise are heated this
way. There's a great photo, I thought
about bringing it, of snow everywhere but the sidewalk's
completely melted. They just use this geothermal
direct use to keep their sidewalks melt-free, ice-free.
It would be kind of a nice way to go.
I don't think we're going to be able to do that here in
Wisconsin. The enhance geothermal has kind
of made the news in the last couple years or so.
This one intrigues me because we can provide base load power with
a small footprint. Just a regular power plant sized
thing. And it can operate any time.
We can locate it anywhere as long as the wells are drilled
deep enough. I want you to note what I say
when I mean drill deep enough. Two to six miles deep.
That's a problem. We don't know how to drill that
deep economically. It's prohibitively expensive to
drill. You can imagine, currently you
need to replace you bits if you drilled down a mile and you have
to pull all of that drill rod, it usually comes, you could
maybe do it in 40-foot sections, maybe 80-foot if you have one of
those big derricks. It's going to take you all day,
a couple days to pull all the drill rod, put a new bit back
on, go back down, drill for a day, and so the deeper you go,
the more bits you're going to have to replace.
You're going to be drilling in granite or some hard, hard rock
like that, and the drilling costs are prohibitive at this
time. Here's the other one that made
the news. In Switzerland they actually
closed a pilot plant down because, and this is the
geophysicist in me coming out, some pilot plants caused
disquieting earthquakes. So they made people
uncomfortable. They were magnitude three and
four, which would hurt this building if it happened, but we
would all be quite disturbed if it happened beneath us.
So three and four generally don't cause damage, but they
make everybody uncomfortable. So those are some issues with
enhanced geothermal. And then the last is ground
sourced heat pumps. These just exchange heat between
the ground and a building, and it's just like a refrigerator in
reverse or a refrigerator when you want to cool your house.
You can either pull heat out of the ground, put it in your
house, or vice versa. It doesn't generate energy, it
just moves it from one place to another.
And it can function anywhere. All right, so let's run down our
options for Wisconsin. What can we viably do here?
Heat pump, definitely. We're doing this now, and I
think nationwide it's a 10% growth for geothermal systems.
I know lots of well drillers in Wisconsin, they used to be
called somebody's son well drilling, now they're called
Ground Source Well Drilling. So a lot of these well drillers
are switching over from drilling water wells to drilling
geothermal wells. It's a growth industry.
So heat pump, it's viable. It works in Wisconsin.
Enhanced geothermal systems, maybe but we've got to reduce
the drilling costs. And in Wisconsin we don't have
very many earthquakes, so maybe we could do the enhanced
geothermal here and not make people uncomfortable.
Direct use, I doubt we do that. Temperatures are unlikely to be
hot enough and we'd put in a heat pump.
Hydrothermal, no. We don't have any hot springs in
Wisconsin. We have a database at the survey
of 10,000 springs, not one of them is warm.
They're all nice, cool, clean places trout would like to live
not other things. And co-produced fluids, no.
There's no petroleum in Wisconsin.
Our survey would be three times as big as it is if we had
petroleum. Not that people haven't looked.
In kind of working on this project, I've run across, I've
looked for really deeps wells in Wisconsin because I wanted to
measure the temperatures, and there's still one if you go west
to Arena down in the Wisconsin River Valley there's a test well
that someone drilled to look for oil near Arena, and it's like
2500 feet deep, and the bottom, I think it's like 1,800 feet of
that or 2,000 feet of that is through granite.
So please, if someone offers you the chance to get into a
drilling company and you hit granite, tell them it's time to
stop the rig. These people kept going through
several thousand feet of granite.
Similar story over in Sheboygan where there's a 4,500-foot well,
and it's at least a couple thousand feet of granite.
That well, we'll be able to test the well in Arena.
The one in Sheboygan has been filled up and it may be lost and
no one knows where it is anymore, but I would love to
test that well. I think it would have use as a
geothermal well. The several thousand feet of
granite has no use for petroleum.
When you hit the granite, that's when you stop looking.
We know that now. Geothermal heat pumps.
So let's talk about the geothermal heat pumps, how they
might work in Wisconsin. So you have your building, you
have stable ground where water temperatures, you can put your
condenser, your coils, in the dirt.
You can put them in rock. You can put them in a pond.
You can do all sorts of different things with them.
You just need a stable water where water temperature is used
to control the building temperatures.
That's actually what we have just across the way at the
Wisconsin Center there. So a horizontal loop, you dig a
trench two to three meters deep. It zig-zags back and forth.
I'm not going to be able to do this in Madison.
My neighbors would not be pleased with the backhoe in
there. And then you put high density
pipe in the trench. You fill it back with soil.
This is what people do out in the country.
You can do a vertical loop where you drill several wells, and
actually I have a neighbor several blocks away who
installed on of these systems in his home and is using geothermal
energy in Madison. And you just drill a bore hole,
you put your pipe down and you circulate there.
You can use the Earth to store and remove the energy.
So the heating cycle is you have your heat pump here, and if
you're going to heat you put cold water in, it picks up some
heat out of the ground, you increase the temperature with
your heat pump, and then you run that to a blower or a heat
exchanger, and you can heat your house with that.
You can also use it to help heat your hot water a little bit as
well too. Cooling cycles, just the
opposite. So rather than take the heat out
as we'd be doing this time of year, in the summer you put the
heat in. So it really balances out nicely
for places farther south. Here in Wisconsin we do way more
heating than we do cooling. So if you're in southern
Illinois, this works really, really well because then you
have more balance. All the heat you take out in the
winter out of the Earth when you heat your home, you can put all
that back in in the summer as you're cooling your home.
So you can get things to balance, and so in Wisconsin we
need to be a little bit careful when we're installing systems
because we keep taking heat out and putting it into our house,
and we can end up cooling off our field, and what that means,
when we cool off our field is that efficiency of our heat pump
goes down and we have to put more energy in to move the heat.
So that's one of the things that we need to be a little bit
careful with. I have a question.
What's the price tag on one of these babies?
Price tag? It depends.
Let me give you a range, though. It depends if you want to heat,
so let's say we're going to heat my house kind of 1500 square
feet. So if I just wanted to do kind
of an auxiliary heating and maybe a quarter and I had room
for a trench, maybe $8,000. If I wanted to do everything
100% and I'm going to have to drill wells, you might be
looking at $32,000. So there's a range.
We'll get to that in a little bit.
That's a great question, though. That includes everything here as
well too. So here's the unit, the heat
pump, an exchanger. It's about the size of a furnace
is really all it is. Here's just some photos of some
people putting in the ground source heat pumps with bore
holes. Here's some well drillers
looking like well drillers. There's a trench excavated.
Here you can see some of the tubes that come out the top.
If you have a lot of wells, it can get pretty complicated all
these tubes going back and forth.
Here's kind of the process. You drill, you put in your pipe
loop going down, comes back up, you fuse it, you make sure it
doesn't leak, you make sure the loops are ready for the unit,
and then you install your heat pump.
Very often these loops don't use water to circulate and transmit
the heat, carry the heat. They use antifreeze so it
doesn't freeze and crack your system.
And there are some environmental concerns.
If the system leaks is that antifreeze going to cause
problems, is it going to cause trouble?
And that's something we need to be thinking about.
So just some facts about geothermal heat pumps.
We could save 2.15 million barrels per year
if 100,000 homes did this. In my 25% to 50% savings on my
utility bill, if I put in that super expensive system, I can
maybe save $800 a year. And let's do the math, it may or
may not work out for me if I'm going to own that home for a
long time. It's going to be really close
for me, and that 25% to 50% also depends where I get my fuel.
Is it more expensive heating oil or is it less expensive natural
gas? The energy consumption emissions
40% less than air source heat pumps.
That's central air if I use it to cool.
Because I'm not exchanging that heat, I'm not blasting that heat
into the hot air, I'm blasting that heat into the cool Earth.
And 70% less in electric. Resistance heating efficiency
more efficient than air source heat pumps, more efficient than
gas furnaces. And that's even the 95%
efficient gas furnace, 75% more efficient than oil furnaces.
Penn, in 2000, did a study of emissions and economic analysis
of ground source heat pumps in Wisconsin.
And he looked at, he did this for, I think, Green Bay,
Madison, and then some place farther north than Green Bay,
but I'm just showing for Madison.
For a large school, 390,000 square feet, energy in costs
savings. So what's the negative of a
savings? That's an increase.
So a negative number means in increase here.
Sorry about that, but that's the way he decided to do his table.
So negative means we're going to use more electricity for the
large school, but we're going to save all of this natural gas.
We're not going to burn that natural gas.
And our yearly annual energy savings are going to be $33,000
if we decide to heat with geothermal.
And our payback time is 10 and a half years.
So for a large system, something big like a school, it really
kind of makes sense. And one of the other points he
made is these systems have a smaller footprint than the
boilers that you can use, and that has value as well too.
So you can think about that. If we look at an office, we're
going to be a little bit more efficient on the electrical
side. And that number's not negative,
that's not a typo. We're actually going to be more
efficient because offices generally have more air
conditioning than homes or schools.
I know my office temperature is cranked way lower than it is at
my home in the summertime for the air conditioning.
Natural gas will save about 10,000 therms and annual energy
savings $6,000, It's going to take a long time, 21 years to
pay back this. Home, this is similar to my
home, I'm going to save on electricity or I'm going to use
more electricity, I'm going to spend more on natural gas, I'm
only going to save about $70, according to their analysis, per
year, and it's going to take 26 years in Madison.
Yeah? >> So this is in terms of
dollars. >> Yeah.
When you're talking about natural gas you're not factoring
in what electricity might be used to produce natural gas.
Yeah, I know. How big are we going to draw the
circle. That's a good point.
I mean, if you think of it globally.
[INAUDIBLE] Yeah, right, and there's a lot
of things associated with natural gas production as well,
too. Yeah, that's right.
Let's expand on that. So if you look at energy use,
right now the energy that produces our electricity is from
coal. So if we can eliminate that coal
use, we're going to end up better off, and that's why,
actually, sometimes switching in Madison to more electricity
results in higher emissions because of our electrical source
in Madison is coal. So if we could switch to Co-Gen
plant produced electricity or the wind generated produced
electricity, this number, our emissions would go way down,
we'd be a lot better off, and that would be something I hope
we eventually look at doing. The whole life cycle of energy
is a tough topic. One other thing to point out,
though, is if you live out in the country and you use propane
to heat rather than natural gas, that higher cost you may recoup
in eight years rather than in 26 that you would have in Madison.
So it may make more sense if you live out in the country.
What prices were used for electricity and gas?
I would have to reference you to this study by Penn.
It would have been like the 2000 or '99 cost in Madison.
They used those. Natural gas has come down or has
held steady because of the fracking technology.
It's a lot more abundant now. All these things are, the
interplay is, I think I probably pulled this payback times are
highly variable and dependent on electric and gas costs.
It's really tough to say. So, again, eight to 26 years.
Take your pick. But you're probably going to
come out ahead in 26 years. Now just look at some examples
around the Madison area. The Wisconsin Institute of
Discovery, just across the way, those red dots are the
geothermal well locations, the proposed ones.
Here's another plot of it. Here's the Wisconsin Institute
of Discovery, and here there's 75 wells, 50 some here, and then
the remainder here. They're all 300 feet deep, and
they're at 20-foot spacing. 300 tons of heat pump capacity.
What is a ton? If you talk to a refrigeration
person they'll start talking in tons rather than kilowatts, and
a ton is the amount of energy needed to turn a ton of water
that's at 32 degrees Fahrenheit into ice.
It comes from the old refrigeration days.
So when they talk about a ton, they're talking about, so four
or five tons, that's a lot of energy to turn four or five tons
of water into ice when it's at near freezing.
And here it's kilowatts, 14 to 18 kilowatts per well.
So when the engineers went out and tested the wells, they were
doing due diligence here. They went out and tested a well
and said we can get four to five tons, 14 to 18 kilowatts of
energy per well in one location. So they tested it.
Unfortunately, the system is coming back at about only two
tons or seven to nine kilowatts per well.
So that heat pump that's circulating, that's taking the
heat out of the ground, is having to work way harder than
they had anticipated. So its efficiency is way down
below what the design was because there's not as much heat
coming out of the ground that the design had hinted at.
And so they think it might be underground water flow.
The First Unitarian meeting house in Madison has 16
geothermal wells they use. Epic Systems in Verona, this is
a huge system. They have 500 borings.
Each one is 300 feet below ground, and they've seen a 40%
energy reduction. So for these really large
facilities, it's making a ton of sense for them to use
geothermal. I do know the drilling out there
has been difficult. I know that dolomite, it's a
carbonate, it's a limestone so it's got big holes, fractures,
maybe caves even, so when they're drilling they'll be
drilling and all the sudden they'll be in air or water.
So it's kind of hard and painful.
It's not easy for them to drill there as well either.
But it's been working for them. Here's an example, there's the
pipe that goes down, carries the warm fluid back out.
And I should say they don't just put these in the ground, they
also put a grout in so that there's a seal between the Earth
and the pipe so things aren't going to run into the ground.
And you can see here they are sticking up out of the ground.
And here's some more of the field that's looking off.
That's probably 151 right there, Highway 151.
And here's the collector system. All those wells have to come
into a manifold. They all get connected and they
run to really big pumps, and then they run to really big heat
pumps that then heat the facility out there at Epic in
Verona. So industry challenges.
Heat pump stuff has high first costs.
It's expensive with no guarantees of performance.
It's more expensive than your boilers and chillers.
I think if we pay more attention to geology, as a geologist I'm
going to say this, we can probably get better guarantees
at performance. If we start looking at what the
geology is, we can start to say better this is how many tons of
energy you can get out of the rock.
And that's one thing that I'm very interested in doing.
Uncertainties, variable fuel composition.
Again, geology. And seasonal underground water
flow. Hydrogeology.
And grouting materials. That's some engineering.
So I think there's room in this. I think the above ground
engineering has worked out. I think we need to be smarter
about what we're doing underground with the geology,
and we can come up with better, more efficient systems.
And so now I'm going to kind of segue into the last piece is the
current geothermal research that we're doing here.
And just some basic information. We want to find basic
information for these systems. I want to get temperatures with
depth. What is the actual geothermal
gradient in Wisconsin? Can we improve heat pump
efficiency? The hotter water coming in, the
more efficient the system. So is one 1,000-foot well,
does that make more sense than five 200-foot wells?
We're going deeper and we should have hotter water going into our
heat pump. Maybe that will pay off to do it
that way. And then, also,
this is my enhanced geothermal pie in the sky.
Wisconsin produces its own electricity.
How deep do we need to drill before we get to temperatures
where we could use to generate electricity?
And then heat flow. Will the well fuel cool off
because we're pulling out all the heat?
And is there enough energy to be able to generate electricity?
So here we're back at this map, and my quibble with this map is
they use three points to draw those contours around Wisconsin.
That's not really enough points for me.
I wish we had more. So that's where we're headed.
The geothermal gradients in Wisconsin, we're the coldest.
Come on, I just don't hardly believe that.
We can do better. So here, if we're looking,
remember, I forget his name right now, where Fox got
two degrees per hundred feet, they're saying we only have
.7 degrees per hundred feet. And the hotspots out here
have almost four degrees per hundred feet.
So I was just wondering about that.
Are we really that cold? This map's just based on
two points in Wisconsin and one in Illinois.
So there we really have to be suspect.
And we have rocks with high heat production, we have all these
granites that we know have high radioactive heat production.
They should produce more heat. So I was expecting higher
temperatures. So let's look at the data we
have. And here's the existing data.
The people who made the map didn't have access to this.
We just pulled it together in this project.
And you can see we go from .6 is the blue
to 2.5 is the red. It's kind of scattered
and I need to figure out what the scatter is, but I'm thinking
we're more in the 1.5. We're out of the .7 range.
We're doing a little bit better than that national map.
We probably have 1.5 or 1.4 degrees per hundred feet.
We may even have two or three. And that may mean that we can
get a lot more heat out of the ground as we drill down deep.
So I would say that map's a little low.
And then if we look at how geology impacts temperatures
with depth, there's a couple things.
The type of lithology insulates the underlying rock.
Sandstone is a good insulator. Heat doesn't travel through it
as well. Granite is not as good an
insulator. Here's some sandstone.
Here's some granite. Groundwater, if you have
groundwater moving from one aquifer down your well to
another one, that makes the heat flow look different when we take
those measurements. And then heat produced in the
rocks. The granites have more heat;
sandstones, less heat. Here's is what we might expect.
A higher gradient across our insulator then we're going to
have gradient down below here too.
And so where we're going to collect additional data?
We're going to look in granites in central Wisconsin that are
going to have higher radioactivity, and then we're
going to look in granites underneath the sandstone.
So this part of Wisconsin has lots of granites.
This part does too but this beige here is sandstone on top
of the granite. So we're going to drill through
that sandstone that's acting like a blanket and see if we can
get higher temperatures. So that sedimentary cover will
insulate the underlying granite. And we're going to drill this
well and this well in the next month or so, I'm thinking, a
thousand-foot well. We drilled a series of three
here, and I'm just showing those in Marathon County in the
granites. And here we're out at the field
site. This was actually in the bottom
of a granite quarry just west of Wausau.
And every time I wanted to do work in this quarry we would get
a half a foot or a foot of snow. And there's my little Dodge
Caliber. And so every time I wanted to go
down into this quarry, I always wondered if my Dodge Caliber was
going to make it back up the hill because usually it was
snow-covered, and I wasn't sure it was going to make it out.
The driller had a plow in front of his pickup so here he
scraped it off for me. But this is one of the pitfalls
of working in a low spot, you're never sure if you're going to
get out. And so here's the drill rig
drilling the thousand-foot well. It took him only three days.
He just plowed through it. It went fast.
Here's some of the cuttings, the ground up rock that comes out
the top of the well as they drilled it.
And here's some of the results from those three wells.
Here we've got the depth. They were all 1,000 feet deep.
And then here's the temperature. I put the Fahrenheit equivalent
down here just to get a sense of it.
And you can see they are all doing something strange.
They all are really high, and then they have a low spot here,
and then they come back up in terms of temperature.
And what I'm interpreting is these things right here, I took
these in the fall so I think the rock was still warmed up from
the summer. So you can imagine hot, cold,
hot, cold. The shallow part of this, if I
went out and measured this in the spring, this is probably
going to be down to zero because it's going to be cold.
So this part of the record is going to get cold and hot, cold
and hot depending on the time of the year.
But as we go deeper, it's going to take longer for that
temperature record to go down and in.
And so I don't know what's going on in this part, these warm
temperatures here. It could be groundwater flow
through cracks that are warming things up.
It could be global climate change.
Our climate could be getting warmer and we're seeing a record
of that in this temperature log. People have analyzed this and
it's pretty commonly seen. Or it could be clearing of the
land surface in a hundred years. The foliage kind of kept things
cool. You strip it away in a quarry,
those rocks heat up as well too. The quarry's been there 40-50
years. So I'm not sure which of these
three things it is, but something's going on strange.
And then, when I did my deep gradient, oh, gosh, maybe those
guys are right. It was only .8 degrees
Fahrenheit per hundred feet. But that's in central Wisconsin
without the overlying sandstones.
And then I looked at the relationship between heat
production, how radioactive those rocks were.
So here's the heat production, and there's heat flow.
This is the kind of rock that we'd expect in Wisconsin,
similar to eastern US. It's a lot of granites without a
lot of cover on it. And I get something down here.
I expected more heat flow and hotter temperatures, and we're
not getting that and I'm not sure why.
It's a nice scientific question but I would have rather had the
other question where it's way hotter than I expected and we're
getting too hot of temperatures. But, anyway, that's a topic for
research. And so the last project we're
going to do is we're going to install one of those deep wells,
and we're going to see if we can get more heat out of a
thousand-foot well than what they typically do now which is a
series of shallow several hundred feet wells.
And by doing that we can maybe use water rather than
antifreeze. Water is easier to pump.
Your pumping costs aren't as high, and it can carry as much
or more heat with it. So we're going to test this out.
This is the dish system, invented by Bruce Walker at
Wisconsin Well & Water Systems. We're going to instrument it,
we'll do all the engineering and check it out.
We have applied for a grant to fund a graduate student to look
at this system and see if it makes sense.
Maybe we can be more efficient. And so here's Dr. Tinjum and
myself and a couple of grad students.
And so I'll see if you have any questions now.
[APPLAUSE]