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[SOUND] Hi, my name is Tom Murphy.

Â I'm a professor in the physics department at UC-San Diego, and today we're

Â going to talk about energy past, present, future,

Â with a particular emphasis on the numbers.

Â And when it comes to numbers, I advocate a real flexibility with numbers, and

Â rounding and just sort of a, a

Â loose manipulation, because math is a lot easier.

Â If you don't take numbers so seriously and some people laugh when I

Â say that, but it's, it's really true that math is easier, division is

Â easier, multiplication is easier if you

Â can manipulate the numbers into something that

Â you can do in your head, then you can quickly understand the scale.

Â Have a problem rather something can work or

Â not work without getting bugged on the details.

Â So, for the instance the number pi and three are virtually the same thing.

Â And ten over three and square root of ten, all about the same.

Â So, you can simplify a lot of otherwise

Â complicated math, just by being flexible and so.

Â For instance, you can round a year to 30 million seconds.

Â You don't need to know that it's 31.55 million to do something useful.

Â Likewise, the US population is something like 300 million people.

Â Forget the fact that it might be 308 one year and 310 the next, whatever.

Â It's about 300 so, for example, the US uses

Â something like 20 million barrels of oil per day.

Â Now, if you have 300 million people using

Â 20 million barrels of oil per day, that's a

Â pretty simple division problem and you come up

Â with 15 days per person per barrel of oil.

Â So a person goes through a barrel of oil in about 15 days.

Â And so, if you think about having a barrel

Â of oil delivered to your house once every 15 days.

Â That's somewhat staggering and puts things in perspective.

Â But oil is only about a third of our total energy demand.

Â So you can scale that again simple math, now it's five days

Â to go through the equivalent energy contained in one barrel of oil.

Â So how much energy is that?

Â Well depends on what units you like.

Â Whether you like, gigajoules or joules or BTUs or [UNKNOWN] all are units of energy.

Â But, you know, comes out to six,

Â gigajoules, 6,000,000,000 joules, 6,000,000 BTUs, 1,700 kilowatt-hours.

Â And this is a very important point, if

Â you divide energy by time, that's called power.

Â And the units for power are watts.

Â So if you take one watt is one joule per second.

Â So if you take six gigajoules, and divide by how many seconds are in

Â five days, you end up with about 10,000 joules per second, or 10,000 watts.

Â That's a rate at which we go through energy.

Â That's not watts per second.

Â That's already a rate And that's a 24 seven

Â constant draw of power that each American is responsible for.

Â Now, we'll come back to putting that in perspective.

Â And for now, I just want to point out.

Â If you take 10,000 watts or ten Kilowatts, multiply it

Â by 24 hours, you get 240 kilowatt hours per day.

Â So, 240 kilowatt hours, that's now an

Â energy cause it's a power, ten kilowatts times

Â a time, in hours, so, that's how many energy units we use per day as Americans.

Â So, just to put 10,000 watts into perspective.

Â Imagine two clothes dryers running full time.

Â They run at about 5,000 watts.

Â Or, you could have, pick your appliance,

Â hairdryers microwave ovens, toaster ovens, space heaters.

Â They all run at about 1,700 watts and that's actually not a coincidence.

Â That's because household circuits are usually rated at 15

Â or 20 amps and so they're kind of maxing out.

Â What a typical outlet can handle.

Â So they're all about 1700 watts, you need about

Â six of those running full time to make 10,000 watts.

Â Here's an interesting one, a human that can, who consumes about 2,000 calories

Â per day that turns out 2,000 calories is a unit of power per day.

Â Sorry, 2,000 calories is a unit of energy.

Â Per day that turns into watts, and it turns out to be 100 watts.

Â So a human runs at about 100 watts.

Â You need 100 humans to make 10,000 watts.

Â That's basically saying that we have 100 energy slaves working for us in America to

Â do the things that we need to get done, so that's quite a work force.

Â 4:44

Now if you know anything about your electricity bill, you

Â might say 240 kilowatt hours a day is an awful lot.

Â And you'd be right because if you look at a typical

Â American household, the household uses about 35 kilowatt hours per day.

Â Okay.

Â That's not a whole lot compared to 240, but we do have to keep in mind that.

Â The primary energy it takes to come

Â up with 35 kilowatt hours of delivered energy,

Â it requires 95 kilowatt hours of primary

Â energy from coal [INAUDIBLE] nuclear or whatever else.

Â So okay and natural gas it's also about 35 kilowatt

Â hours a day usually the gas bill is in therms.

Â So that looks a little bit different, but, you can

Â always convert units between each other if you need to.

Â A typical household uses about three gallons of gas a day, each

Â gallon has about 36 kilo watt hours, contained in it in energy.

Â So that's a little over 100 kilo watt hours in gasoline.

Â Add all those up you've got about 235 kilo watt hours a day, and it sounds

Â like we've reached our 240, but not so

Â fast because a household contains more than one person.

Â So when you work it all out it comes out to

Â about 95 kWh/day per person spent in the home or personal vehicle.

Â Ok, that's just 40% of the total, so where's all the rest?

Â Well we have a huge infrastructure Supporting our lifestyle.

Â We have industry, we have agriculture growing our food, transportation

Â to move things all around to our stores, to each other.

Â We have the consumer and commercial world.

Â We have defense and government.

Â All those things take energy.

Â All of that happens outside of our household.

Â 6:30

Our standard of living demands that we have these things happening,

Â and so we really have to take responsibility for all that energy.

Â And also realize that almost all of it

Â comes from fossil fuels, which are finite in nature.

Â If you've never looked at it, the Energy Information Agency puts

Â out every year an annual energy review This is from 2011, and

Â they have some nice graphs where you see pictorially how much

Â comes from domestic fossil fuel, how much comes from imported fossil fuel.

Â Here's nuclear and here's renewable,

Â mostly hydroelectric and some burning wood.

Â And then where it goes, residential, commercial, industrial, transportation.

Â They also have some nice diagrams that sort

Â of detail where, which things go to where.

Â So 71% of petroleum goes to transportation, but you can

Â ask the inverse question, say that transportation gets 93% of its

Â energy from petroleum, or nuclear power, 100% of it goes to

Â making electricity, but electricity is pretty diverse, 21% comes from nuclear.

Â So a lot of great information on this kind of spider web.

Â Diagram.

Â So, one point I want to make that's very important to me, is that, we

Â live in a very special time and place, here in America at this age.

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If our dream, as stated by many, is

Â to have ten billion people, which are coming, live

Â at US or Western standards, that implies something like

Â 100 terrawatts of power necessary to make that happen.

Â And so, that makes the fossil fuel look like an absolute tiny blip.

Â And we have all this energy coming from

Â presumably renewables to last you know, for the millennia.

Â And it's not clear what makes us think we can do this.

Â There's no precedent for it.

Â So, let's just look at some of the renewables and what we can get.

Â So, solar power reaching land comes up to a staggering 20,000 terawatts.

Â And, even if you have all kinds of practical limitations, you could

Â probably easily get hundreds of terawatts out of solar, if you had to.

Â So, that looks pretty promising.

Â But take the next step down and we look at the

Â entire biological activity on Earth, all organisms from plankton to elephants.

Â We're looking at 60 terawatts or there about.

Â 11:59

So the lesson for me is that this makes me sit up

Â and pay attention because we're in an all hands on deck situation.

Â We have a, an energy demand that's huge,

Â and continuation of this under alternatives is not guaranteed.

Â We don't know for sure that we can make this work.

Â There are problems and issues in the way.

Â That suggests we need to tackle this with

Â a research effort that dwarfs everything we've ever seen.

Â You know, Apollo-scale project, Manhattan project, Should look tiny compared to what

Â we need to do to respond to this energy crisis of the future.

Â So, but we don't know even if we do a

Â lot of research, we're not going to guarantee that, that's going to work.

Â So, we also are wise to think about ways to trim down, use less energy this way.

Â So personally at home, I've reduced my energy footprint by about four

Â or five times, and I still live a Western lifestyle more or less.

Â And so you can do that, but it's not just at home.

Â Your consumer choices matter.

Â So, how often and where you travel, what you eat, you know, meat for

Â instance, costs a lot of energy How can you buy things or replace things?

Â