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Could Earth's Heat Solve Our Energy Problems?

this episode of real engineering is

brought to you by brilliant a problem

solving website that teaches you to

think like an engineer one of the

biggest challenges facing mankind today

is our quest to transition to renewable

energy overhauling our entire

electricity grid requires drastic

changes to be made in the way we produce

transport use and store electricity we

have explored in past videos that with

the lowering cost of solar and wind

we are beginning to hit a point of

imbalance in the grid where places like

California are wasting massive amounts

of energy in the summer months when

solar is at its peak and not producing

enough in winter to deal with this

problem California is now installing

gigantic battery storage facilities in

places like Moss Landing to store that

excess for later use but the amount of

battery storage that they will require

as our percentage of renewables

increases is going to cost the state

billions if not trillions we could

drastically decrease this dependence on

batteries if we could find a nice stable

energy source that did not harm our

planet some want to turn to nuclear

energy but what if I told you this

solution may be lying directly under our

feet imagine an ancient hidden energy

source deep within every square meter of

our planet's surface it's clean flexible

virtually limitless completely renewable

never turns off and virtually carbon

free geothermal energy is produced by

the Earth's inherent heat the center of

the earth is as hot as the surface of

the Sun through convection that heat

warms the outer layers of the planet but

where does that heat come from much of

it comes from gravitational forces when

the planet first formed four billion

years ago some heat is generated from

friction as denser elements make their

way to the Earth's core the other source

of Earth's internal heat occurs in the

upper mantle and crust where the decay

of radioactive isotopes like

potassium-40

creates energy and in turn heat if we

could find a way to safely and

cost-effectively access that heat our

energy problems would be solved in year

that he does come to the surface in some

easily accessible locations at

temperatures of 700 degrees or more

rocks become partially melted becoming

magma driving a variety of geothermal

phenomena if magma flowing underground

heats gases or water it can create

bubbling hot springs and geysers

undersea hot vents and natural steam

vents these features can provide water

that's more than 200 degrees more than

enough to run a steam turbine geothermal

hot spots like this are found near the

boundaries of tectonic plates like

Iceland in volcanic Li active areas like

Turkey or in some places where the

Earth's crust is thin like America's

Yellowstone National Park these places

provide low hanging fruit to harvest the

Earth's heat for our energy needs each

year enough heat flows to the planet's

surface to meet our total global energy

consumption twice over and the

geothermal reservoir is boundless heat

within 10 kilometres of Earth's surface

contains roughly 50,000 times more

energy than all fossil fuel resources

worldwide yes geothermal energy makes up

less than 1% of global installed

electricity capacity this isn't even a

technology issue of the global potential

for geothermal power using off-the-shelf

technology only 7% has been tapped so in

the fight to transform our global energy

system why haven't we adopted this

energy source in a serious way

let's first look at our low-hanging

fruit that are not being used to their

full potential naturally occurring

hydrothermal reservoirs feature hot

water that percolates near the surface

through porous or cracked rock layers

this is the easiest form of geothermal

energy to harvest and can be tapped in

several ways which we've been doing for

centuries human societies have used the

heat from low-temperature geothermal

energy for millennia among the most

famous examples may be the hot springs

of Bath England established by Roman

engineers in 60 seee here 1 million

liters of water percolates to the city

center of bath

every day at a temperature of about 45

degrees heating recreational baths and

heating some buildings this hot water

replenishes itself as rain that falls in

nearby hills seeps through porous

limestone deep underground where it is

heated and rises back to the surface but

convenient locations like this where the

right combination of a water cycle with

porous rocks underground and a heat

source close enough to the surface to

heat it are rare and ones that can

provide water with enough heat and

pressure to run a steam turbine are even

rarer this particular source is not

suitable as 45 degrees as far off the

lowest temperature we can employ there

are three basic types of geothermal

energy generators all three share the

same basic idea take hot water or steam

from a geothermal reservoir and run it

through a steam turbine where it loses

energy and condenses before being pumped

back underground to keep the cycle going

dry steam generators take the steam

directly from the source to run the

turbine a flash steam power plant takes

extremely hot water under pressure above

100 degrees and expands it quickly to

lower its boiling point and turn it to

steam to run the steam turbine these

both require higher temperature sources

that are rare but a relatively common in

geothermally active regions like Iceland

Italy Austria and around the Pacific

Ring of Fire and in these locations

geothermal energy is common and is

expected to grow as much as 28% in the

next four years with countries in

Southeast Asia expected to see the

largest growths like Indonesia and the

Philippines but we want to exploit

geothermal energy outside of these

regions no matter how much power we

extract we can't transport it fair

before power losses due to resistance in

the cables saps it away the third type

of generator provides the highest

potential for expanding geothermal

energy as it can utilize the lowest

temperature sources this system is

called a binary cycle system in a binary

cycle power plant warm water from a

geothermal source passes through a heat

exchanger where

as heat with a closed loop containing a

fluid with a low boiling point like

pentane which has a boiling point of 36

degrees the lower boiling point allows

it to transition to a gas at a much

lower temperature allowing it to run a

turbine at a lower temperature this

system has allowed countries like

Germany which lacks any shallow depth

geothermal resources to grow their

geothermal energy market in recent years

where temperatures as low as 100 degrees

Celsius being utilized that figure is

important because the higher the

temperature the deeper we have to drill

different areas have different

geothermal gradients which is a measure

of how quickly temperatures rise as we

drill down this map shows a rough

estimate of the geothermal gradient

across the US with the highest gradients

been found in Oregon and Idaho reaching

as high as 70 degrees per kilometer this

is important as to access this heat in

areas where it doesn't naturally come to

the surface in an accessible way we need

to drill down and the further we need to

drill the more expensive it becomes

typically we have only used geothermal

resources where the natural permeability

of the rocks allows a convective heat

cycle but a new technology by the name

of enhanced geothermal systems or EGS

may open the door to geothermal energy

in more regions it works like this the

first step is to drill an injection well

into a formation of hot rocks then

engineers inject fluid at pressure to

form cracks or enlarge existing ones

this increases the area over which heat

exchange with the rocks can occur to

increase this area even further a

non-toxic and degradable material is

pumped down to fill these cracks and

allow the pressure to form new cracks as

we drill further down once we have

opened an adequate number of passages

for the water to fill we can drill

additional holes that can act as an

outlet for our hot water as we pump more

underground a report by MIT in 2006

found that EGS could provide electricity

at a cost as low as three point nine

cents per kilowatt-hour roughly

equivalent to a coal-fired power plant

the united states government

esta

it's that new geothermal power plants

could produce 60 gigawatts of electric

power on American soil by 2050 mostly

through EGS systems now I know what you

are thinking this sounds a lot like the

controversial practice of fracking but

it doesn't use toxic fracking fluid

which can seep into our water cycle it

uses water and some safe additives but

it's not all plain sailing to make this

work we need to create great volumes of

fractures and cracks and this can have

some disastrous consequences in 2017

drilling at a proposed site for EGS in

Pohang south korea is thought to have

triggered an earthquake of 5.4 magnitude

that injured 135 people a previous

incident occurred at an EGS plant in

Basel Switzerland in 2006 when drilling

may have caused the quake of magnitude

3.4 and several buildings were damaged

both projects were cancelled as a result

red tape is a huge obstacle for

geothermal energy in the United States

for example there's less environmental

paper work and fewer approvals required

for drilling for oil than drilling a

geothermal well tax credits for wind and

solar power projects are 30 percent

while the tax credit for geothermal is

only 10 percent on top of all this

drilling is very expensive and as we

have seen doesn't guarantee a successful

geothermal plant you could waste months

of your time digging a two kilometre

hole in the ground and the productivity

of the well could be too small to make

the project worthwhile this makes it

difficult to find investors willing to

bet their money on it it simply makes

more sense to invest in solar and wind

despite the challenges there's real hope

for expanding geothermal energy the

industry can build off of recent

improvements in drilling technology

engineers are developing new kinds of

drills for geothermal wells and better

techniques for cementing wells drilled

into hot rocks the earthquake risk is

real but engineers have protocols for

monitoring with seismometers to ensure

that the seismic risk can be assessed

early on in the case of the Bassel

accident the EGS facility was located

over a seismic fault

due to the proximity of hot rocks to the

surface once the shaking started fluid

injection was halted immediately so far

geothermal projects haven't attracted

strong political support in the West

both they also haven't managed to draw

major opposition suggesting that easing

permitting rules for the technology may

not be so challenging as commercial

interest in this clean energy source

Rises political support force should

follow especially if some smart

politician realizes that it can be a

rallying call for getting out of work

oil drilling texts back to work

sometimes the struggle to convert the

global energy system to renewables can

seem out of reach and feel hopeless but

in the case of geothermal energy there's

an exciting source of electricity and

heat that could power our future and

it's right below our feet as I said at

the start of the video much of the

energy present within the earth is

formed as a result of gravitational

forces you can learn everything gravity

is capable of by taking this course on

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planetary motion and understand orbital

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effect where spaceships use a planet's

gravity to increase their speed it's a

fascinating course that I can't

recommend enough or you could complete

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