TedTest

From the Ted Talk by Alexandros Charalambides: Why aren't we only using solar power?

Unscramble the Blue Letters

We have some good reasons to completely switch over to solar power. It's ceaehpr in many cases, and definitely more sustainable than our dednencpae on traditional power plants that use resources like coal, which will eventually run out. So why don't we replace these traditional plants with solar egreny? Because there's one factor that makes solar power very unpredictable: cloud cover. As the sun's rays move towards Earth, some get absorbed by the Earth's atmosphere, some are reflected back into outer sapce, but the rest make it to the Earth's surface. The ones that aren't deviated are cllaed direct inrcaardie. The ones that are deflected by clouds are called diffuse irradiance. And those rays that first get reflected by a surface, like a nearby building, before reaching the solar energy system are called reflected irradiance. But before we can examine how clouds aecfft the sun's rays and electricity production, let's see how these solar energy systems work. First up, we have solar towers. These are made up of a central tower suerdounrd by a huge filed of mirrors that track the sun's path and focus only the direct rays onto a single point on the tower, kind of like an eager beachgoer. The heat generated by these rays is so immense that it can be used to boil water puncirdog steam that drives a traditional truibne, which makes electricity. But when we say solar energy syemsts, we're usually talking about photovoltaics, or solar panels, which are the systems most commonly used to generate solar power. In solar panels, photons from the sun's rays hit the surface of a panel, and electrons are released to get an eltceric current going. Solar panels can use all types of irradiance, while solar towers can only use deicrt irradiance, and this is where clouds become important because depending on their type and lcaootin relative to the sun, they can either increase or decrease the auomnt of electricity produced. For instance, even a few cuumlus clouds in front of the sun can reduce the electricity production in solar towers to almost zero because of this dependence on direct rays. In solar panels, those clouds would dscraeee energy output as well, though not as much because solar panels can use all types of irradiance. However, all this depends on the cdluos ecaxt positioning. Due to reflection, or a particular phenomeon called Mie scattering, the sun's rays can actually be focused forward by clouds to create a more than 50% increase in the solar irradiance ricaehng a solar panel. If this potential increase isn't accounted for, it could dmgaae the solar panel. Why does this matter? Well, you wouldn't want this lesson to stop just because a cloud passed over the panel on your roof. In solar towers, huge tanks of molten salt or oil can be used to store any excess heat and use it when needed, so that's how they manage the problem of fluctuating solar irradiance to smooth out electricity piucoortdn. But in the case of solar panels, there currently isn't any way to aobarfldfy sorte extra energy. That's where traditional power plants come in because to correct for any fluctuations in these salor powered plants, extra electricity from traditional sources always needs to be available. But then why aren't these tradtional pwoer plants just used as a backup, instead of us humnas depending on them as our main sources of energy? Because it's impossible for an employee at a coal fired or a nuclear pnalt to turn a knob to pdoruce more or less electricity deepnding on how many clouds there are in the sky. The response time would simply be too slow. Instead, to accommodate these fcitutaulnos, some extra electricity from traditional power plants is always being produced. On celar sky days, that etrxa etcilritecy might be wasted, but when cloudy skies prevail, it's what fills the gap. This is what we currently depend on for a constant supply of energy. For this reason, a lot of researchers are interested in forcasting the motion and formation of clouds through slitlteae images or cameras that look up at the sky to maximize the energy from solar power plants and minimize energy waste. If we could accomplish that, you'd be able to enjoy this vedio powered solely by the sun's rays, no matter what the weather, although if the sun is snhinig, you may be tempted to venture outside to go and do a different kind of could gazing.

Open Cloze

We have some good reasons to completely switch over to solar power. It's _______ in many cases, and definitely more sustainable than our __________ on traditional power plants that use resources like coal, which will eventually run out. So why don't we replace these traditional plants with solar ______? Because there's one factor that makes solar power very unpredictable: cloud cover. As the sun's rays move towards Earth, some get absorbed by the Earth's atmosphere, some are reflected back into outer _____, but the rest make it to the Earth's surface. The ones that aren't deviated are ______ direct __________. The ones that are deflected by clouds are called diffuse irradiance. And those rays that first get reflected by a surface, like a nearby building, before reaching the solar energy system are called reflected irradiance. But before we can examine how clouds ______ the sun's rays and electricity production, let's see how these solar energy systems work. First up, we have solar towers. These are made up of a central tower __________ by a huge _____ of mirrors that track the sun's path and focus only the direct rays onto a single point on the tower, kind of like an eager beachgoer. The heat generated by these rays is so immense that it can be used to boil water _________ steam that drives a traditional _______, which makes electricity. But when we say solar energy _______, we're usually talking about photovoltaics, or solar panels, which are the systems most commonly used to generate solar power. In solar panels, photons from the sun's rays hit the surface of a panel, and electrons are released to get an ________ current going. Solar panels can use all types of irradiance, while solar towers can only use ______ irradiance, and this is where clouds become important because depending on their type and ________ relative to the sun, they can either increase or decrease the ______ of electricity produced. For instance, even a few _______ clouds in front of the sun can reduce the electricity production in solar towers to almost zero because of this dependence on direct rays. In solar panels, those clouds would ________ energy output as well, though not as much because solar panels can use all types of irradiance. However, all this depends on the ______ _____ positioning. Due to reflection, or a particular phenomeon called Mie scattering, the sun's rays can actually be focused forward by clouds to create a more than 50% increase in the solar irradiance ________ a solar panel. If this potential increase isn't accounted for, it could ______ the solar panel. Why does this matter? Well, you wouldn't want this lesson to stop just because a cloud passed over the panel on your roof. In solar towers, huge tanks of molten salt or oil can be used to store any excess heat and use it when needed, so that's how they manage the problem of fluctuating solar irradiance to smooth out electricity __________. But in the case of solar panels, there currently isn't any way to __________ _____ extra energy. That's where traditional power plants come in because to correct for any fluctuations in these _____ powered plants, extra electricity from traditional sources always needs to be available. But then why aren't these tradtional _____ plants just used as a backup, instead of us ______ depending on them as our main sources of energy? Because it's impossible for an employee at a coal fired or a nuclear _____ to turn a knob to _______ more or less electricity _________ on how many clouds there are in the sky. The response time would simply be too slow. Instead, to accommodate these ____________, some extra electricity from traditional power plants is always being produced. On _____ sky days, that _____ ___________ might be wasted, but when cloudy skies prevail, it's what fills the gap. This is what we currently depend on for a constant supply of energy. For this reason, a lot of researchers are interested in forcasting the motion and formation of clouds through _________ images or cameras that look up at the sky to maximize the energy from solar power plants and minimize energy waste. If we could accomplish that, you'd be able to enjoy this _____ powered solely by the sun's rays, no matter what the weather, although if the sun is _______, you may be tempted to venture outside to go and do a different kind of _____ gazing.

Solution

solar
systems
store
space
field
clouds
extra
cloud
dependance
humans
fluctuations
called
damage
power
clear
produce
affordably
energy
satellite
decrease
irradiance
location
direct
reaching
cheaper
cumulus
depending
surrounded
amount
video
production
plant
turbine
producing
exact
electric
shining
affect
electricity

Original Text

We have some good reasons to completely switch over to solar power. It's cheaper in many cases, and definitely more sustainable than our dependance on traditional power plants that use resources like coal, which will eventually run out. So why don't we replace these traditional plants with solar energy? Because there's one factor that makes solar power very unpredictable: cloud cover. As the sun's rays move towards Earth, some get absorbed by the Earth's atmosphere, some are reflected back into outer space, but the rest make it to the Earth's surface. The ones that aren't deviated are called direct irradiance. The ones that are deflected by clouds are called diffuse irradiance. And those rays that first get reflected by a surface, like a nearby building, before reaching the solar energy system are called reflected irradiance. But before we can examine how clouds affect the sun's rays and electricity production, let's see how these solar energy systems work. First up, we have solar towers. These are made up of a central tower surrounded by a huge field of mirrors that track the sun's path and focus only the direct rays onto a single point on the tower, kind of like an eager beachgoer. The heat generated by these rays is so immense that it can be used to boil water producing steam that drives a traditional turbine, which makes electricity. But when we say solar energy systems, we're usually talking about photovoltaics, or solar panels, which are the systems most commonly used to generate solar power. In solar panels, photons from the sun's rays hit the surface of a panel, and electrons are released to get an electric current going. Solar panels can use all types of irradiance, while solar towers can only use direct irradiance, and this is where clouds become important because depending on their type and location relative to the sun, they can either increase or decrease the amount of electricity produced. For instance, even a few cumulus clouds in front of the sun can reduce the electricity production in solar towers to almost zero because of this dependence on direct rays. In solar panels, those clouds would decrease energy output as well, though not as much because solar panels can use all types of irradiance. However, all this depends on the clouds exact positioning. Due to reflection, or a particular phenomeon called Mie scattering, the sun's rays can actually be focused forward by clouds to create a more than 50% increase in the solar irradiance reaching a solar panel. If this potential increase isn't accounted for, it could damage the solar panel. Why does this matter? Well, you wouldn't want this lesson to stop just because a cloud passed over the panel on your roof. In solar towers, huge tanks of molten salt or oil can be used to store any excess heat and use it when needed, so that's how they manage the problem of fluctuating solar irradiance to smooth out electricity production. But in the case of solar panels, there currently isn't any way to affordably store extra energy. That's where traditional power plants come in because to correct for any fluctuations in these solar powered plants, extra electricity from traditional sources always needs to be available. But then why aren't these tradtional power plants just used as a backup, instead of us humans depending on them as our main sources of energy? Because it's impossible for an employee at a coal fired or a nuclear plant to turn a knob to produce more or less electricity depending on how many clouds there are in the sky. The response time would simply be too slow. Instead, to accommodate these fluctuations, some extra electricity from traditional power plants is always being produced. On clear sky days, that extra electricity might be wasted, but when cloudy skies prevail, it's what fills the gap. This is what we currently depend on for a constant supply of energy. For this reason, a lot of researchers are interested in forcasting the motion and formation of clouds through satellite images or cameras that look up at the sky to maximize the energy from solar power plants and minimize energy waste. If we could accomplish that, you'd be able to enjoy this video powered solely by the sun's rays, no matter what the weather, although if the sun is shining, you may be tempted to venture outside to go and do a different kind of cloud gazing.

Frequently Occurring Word Combinations

ngrams of length 2

collocation	frequency
power plants	5
solar power	4
traditional power	3
solar energy	3
solar towers	3
extra electricity	3
direct rays	2
solar panels	2
electricity production	2
solar irradiance	2
solar panel	2

ngrams of length 3

collocation	frequency
traditional power plants	3

Important Words

absorbed
accommodate
accomplish
accounted
affect
affordably
amount
atmosphere
backup
beachgoer
boil
building
called
cameras
case
cases
central
cheaper
clear
cloud
clouds
cloudy
coal
commonly
completely
constant
correct
cover
create
cumulus
current
damage
days
decrease
deflected
depend
dependance
dependence
depending
depends
deviated
diffuse
direct
drives
due
eager
earth
electric
electricity
electrons
employee
energy
enjoy
eventually
exact
examine
excess
extra
factor
field
fills
fired
fluctuating
fluctuations
focus
focused
forcasting
formation
front
gap
gazing
generate
generated
good
heat
hit
huge
humans
images
immense
important
impossible
increase
instance
interested
irradiance
kind
knob
lesson
location
lot
main
manage
matter
maximize
mie
minimize
mirrors
molten
motion
move
nearby
needed
nuclear
oil
outer
output
panel
panels
passed
path
phenomeon
photons
photovoltaics
plant
plants
point
positioning
potential
power
powered
prevail
problem
produce
produced
producing
production
rays
reaching
reason
reasons
reduce
reflected
reflection
relative
released
replace
researchers
resources
response
rest
roof
run
salt
satellite
scattering
shining
simply
single
skies
sky
slow
smooth
solar
solely
sources
space
steam
stop
store
sun
supply
surface
surrounded
sustainable
switch
system
systems
talking
tanks
tempted
time
tower
towers
track
traditional
tradtional
turbine
turn
type
types
venture
video
waste
wasted
water
weather
work