How Can We Store Renewable Energy?: Crash Course Climate & Energy #4

say you wanted to power the entire Earth with solar power I estimate you would need around oh a hundred and twelve thousand square kilometers of at least a moderately efficient photoviteic panels if that sounds like a lot that's because it is but it's also not because those panels could also all fit in just a little more than one percent of the Saharan Desert and with the

falling cost of solar panels it could be done way more cheaply than making the same amount of Power with nuclear fuel but like we talked about last time in episode three there's a big problem with relying on renewable resources like solar and wind what happens to our electricity When the Sun Goes Down sometimes the rotation of the earth can be a real bummer another problem we

need reliable ways to store and transmit electricity so that it's available when and where we need it and that is going to require a lot more technology and a lot more space hi hi I'm M Jackson and this is Crash Course climate and energy [Music] electricity rules our lives we use it from the moment we wake up and check our phones when we cook when we

work wind down when we watch YouTube videos all the way to the end of the day when we switch off the lights and watch more YouTube and then eventually go to sleep electricity won this MVP status thanks to its versatility as an energy carrier as tiny particles called electrons flow within conductive materials think copper aluminum gold or really any metal they push energy from one place

but like you can probably guess by this point that's easier said than done right now all of our homes and industries are connected to their electricity Supply by a vast electric grid last time we compared that electric grid to a bucket of water imagine this time the bucket is the grid and and the electricity is the water power plants put water into the bucket and then

when you flip the lights on that water flows through a hose to wherever you are crucially the utility companies are the bucket managers it's their job to control the flow of electricity in and out of the bucket and make sure it stays full throughout the day traditionally power plants that use fossil fuels have produced electricity on demand to effectively pump water back into the bucket to

replace whatever is used up but as we lean more on renewable resources like wind and solar we won't have that flexibility we don't get a pick when the sun shines or when the wind blows and that can lead to overproduction basically on a really sunny or really windy day so much water could be poured into the bucket that it could overflow and damage the whole system

to avoid this utility companies do something called curtailment where they selectively switch off solar panels or wind turbines at their most productive times if you've ever noticed a wind turbine not spinning on a pretty windy day and wondered why well there's a good chance that's why let's head to the thought bubble the amount of electricity a neighborhood uses varies during the day depending on people's habits

and as much as we like to feel unique we really are habitual creatures in the morning you and your neighbors get up turn the lights on make coffee watch YouTube videos so the load on the electric grid gradually ramps up after that things tend to stay pretty constant during the day because you're either gone or because you're working at home with the same lights and same

devices drawing power but then comes evening people are coming home it's getting dark so you're turning on more lights around the house cooking food playing music chilling in front of the TV so the load on the grid Peaks to its highest level of the day then as everyone goes to bed electricity usage tails off to its lowest levels but this curve of Rise flat Peak and

drop changes when you add solar panels panels produce most of their electricity during the day so they easily meet the demand of the midday plateau in fact the electric grid is being asked to supply less power than what's being produced so wind and solar power plants may even switch off to avoid overproduction but then comes evening and it's like one minute you're jogging at a comfortable

pace and the next you're sprinting full speed away from a bear or towards an ice cream truck Peak demand happens right when the Sun goes down so good night solar power the base load fossil fuel and nuclear power plants suddenly have to step in to supply all the electricity ramping up production very quickly to pick up the slack this pattern of midday sag and steep evening

incline has a name the duck curve because if you squint and tilt your head to the side it kind of looks like a duck look we don't make the names here thanks thought bubble as cute as it sounds the duck curve spells trouble for the electricity Grid it's really inefficient and definitely not economical for power plants to keep switching off and then ramping up Supply so

quickly that doesn't mean solar panels are bad idea there's still carbon free renewable energy but the way we do electricity just wasn't made for them now one way to get around this is to change our habits that's called load shifting basically we could start using most of our electricity when it's cheapest to generate that could mean running the washing machine in the middle of the night

when there's less Demand on the grid or it could mean switching on an electric heater in the day when solar power is the most plentiful those individual changes add up but as we talked about before and we'll talk about again tackling climate change isn't just about you it's about collaboration and even if everybody did midnight laundry that wouldn't be enough to completely flatten the duct curve

plus what about when you really need to binge a nature show during Peak evening hours or at any time of the day or night when a hospital needs electricity to perform surgeries take X-rays keep Vital sign monitors running for that there's another solution we could level out the duck curve by storing electricity when it's made in excess and dishing it out when we need it the

most for example any extra electricity solar panels make during the day could be stored and then used in the evening so power plants don't have to work as hard and there are already multiple ways we could make this happen first you've got electrochemical storage AKA your everyday battery batteries contain charged particles and when you plug in your phone those particles go from one end of the

battery to the other and hang out there until you need them then when you unplug your phone and start scrolling through cat photos the particles release energy by whipping back to the other side of the battery generating an electric current is the go batteries are fast and easy to charge they're relatively safe and portable and they can hold their energy for a very long time the

trouble is electrochemical batteries often use metals that are rare on Earth so assembling enough of them to store electricity for an entire grid would be costly to extract these Rare Earth minerals you would need big mining operations that would damage the environment which is kind of the opposite of what we're going for here so instead excess electrical energy could be stored by chemical means we'd use

extra electricity to split water molecules into hydrogen and oxygen in a process called electrolysis then when we needed electricity later we could generate it using a hydrogen fuel cell here the hydrogen entered chamber with a special membrane the membrane lets prior to the hydrogen atoms pass through their positively charged protons but the negatively charged electrons have to take a different path to the other end of

the fuel cell and that stream of electrons creates an electric current the only waste product here is water so this is a carbon free option that uses and regenerates one of the Earth's most abundant resources the catch hydrogen is a really lightweight gas meaning its molecules are quite spread out so it takes up a lot of space and is difficult to compress into small containers or

storage so there's a third option that's carbon free and it deals with regular unsplit water it's called mechanical energy when there's electricity to spare water is pumped to the top of a big hill and kept there in a reservoir then when electricity is needed again water is released to turn a turbine and generate power on demand this is basically the same technology as a hydroelectric Dam

you just add an uphill pump so this is something we could actually develop relatively easily but it's not the most efficient technology you need a huge space and at least one big hill for a reservoir if you're going to rely on gravity alone sorry Kansas so the last option is thermal energy storage here excess electricity is used to heat a material with a high boiling point

like molten salt some salts don't melt until they reach several hundred degrees Celsius so they're really not something you want to put on your fries because your food would immediately catch explosion pardon fire but these salts they're a good heat source so when the demand for electricity increases the heat from the salt can be transferred to water to make Steam turn turbines and generate the electricity

we need it seems simple and existing fossil fuel plants could even be repurposed to contain thermal storage and steam generators except molten salt also has a bad habit of corroding everything it touches and fighting that is a constant expensive battle so is keeping the salt hot enough to stay liquid especially if you want to do that with renewable energy as great as they are renewable energy

sources like wind or solar just don't have a high energy density compared to fossil fuels in other words to generate the same amount of energy as a fossil fuel power plant using solar panels you'd need anywhere from 25 to 2 000 times as much space compared to fossil fuels all these storage options can have a high green premium or upfront cost difference so there is one

more path we start sharing buckets across locations even time zones in other words instead of saving spare electricity for when we need it we could transmit that electricity to somewhere that needs it right now connecting grids over wider areas would allow utility companies to deliver electricity more efficiently and more equitably and it could overcome some of the limitations with renewable energy one region that's super Sunny

could send power to a city that's a bit more overcast this is Seattle hey Phoenix unfortunately this is hard with the grids we have at the moment our buckets only serve certain regions unless you happen to be near Indianapolis right now my Region's electricity bucket not connected to yours but this is starting to change for instance the trans-west Express in the U.S say that three times

fast is planning to take wind power from Wyoming and deliver it all the way to California over a thousand kilometers away big Regional projects like this will help each state reduce its emissions while requiring fewer solar panels and wind turbines than if each state powered itself alone you know what they say teamwork Makes the Dream Work in the end decarbonizing electricity won't have a single solution

like filling part of the Sahara with solar panels I mean if transmitting electricity between states is hard right now imagine the challenge of transmitting electricity from one part of Africa to the rest of the world and that's not even mentioning how we'd store it so obviously collaboration will be key here some regions might work on advancing batteries While others might focus on connecting grids and you

you might contribute to research or policy or Tech that furthers the conversation in areas you're interested in figuring out the best ways to store and transmit electricity won't be easy but the payoffs will be huge because whatever strategy we come up with won't just help us make carbon free electricity the advancements will affect all other big carbon emitting sectors like Transportation or heating our homes we'll

get into that next time special thanks to Harry brison this episode's combination bucket manager wind turbine Wrangler and duck curve illustrator you really held it down this episode Harry thanks for keeping the lights on and the buckets from overflowing and for supporting us on patreon crash course climate and energy is produced by complexity with support provided by breakthrough energy and Gates Ventures this episode was filmed

at Castle Garrity studio and most made with the help of all of these nice people if you want to help keep crash course free for everyone forever you can join our community on patreon