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[SOUND] Hi, my name is Tom Murphy.

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

going to talk about energy past, present, future,

with a particular emphasis on the numbers.

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

rounding and just sort of a, a

loose manipulation, because math is a lot easier.

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

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

easier, multiplication is easier if you

can manipulate the numbers into something that

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

Have a problem rather something can work or

not work without getting bugged on the details.

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

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

So, you can simplify a lot of otherwise

complicated math, just by being flexible and so.

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

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

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

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

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

something like 20 million barrels of oil per day.

Now, if you have 300 million people using

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

pretty simple division problem and you come up

with 15 days per person per barrel of oil.

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

And so, if you think about having a barrel

of oil delivered to your house once every 15 days.

That's somewhat staggering and puts things in perspective.

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

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

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

So how much energy is that?

Well depends on what units you like.

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

But, you know, comes out to six,

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

And this is a very important point, if

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

And the units for power are watts.

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

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

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

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

That's not watts per second.

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

constant draw of power that each American is responsible for.

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

And for now, I just want to point out.

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

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

So, 240 kilowatt hours, that's now an

energy cause it's a power, ten kilowatts times

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

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

Imagine two clothes dryers running full time.

They run at about 5,000 watts.

Or, you could have, pick your appliance,

hairdryers microwave ovens, toaster ovens, space heaters.

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

That's because household circuits are usually rated at 15

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

What a typical outlet can handle.

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

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

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

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

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

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

So a human runs at about 100 watts.

You need 100 humans to make 10,000 watts.

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

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

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Now if you know anything about your electricity bill, you

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

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

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

Okay.

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

The primary energy it takes to come

up with 35 kilowatt hours of delivered energy,

it requires 95 kilowatt hours of primary

energy from coal [INAUDIBLE] nuclear or whatever else.

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

hours a day usually the gas bill is in therms.

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

always convert units between each other if you need to.

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

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

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

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

like we've reached our 240, but not so

fast because a household contains more than one person.

So when you work it all out it comes out to

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

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

Well we have a huge infrastructure Supporting our lifestyle.

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

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

We have the consumer and commercial world.

We have defense and government.

All those things take energy.

All of that happens outside of our household.

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

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

And also realize that almost all of it

comes from fossil fuels, which are finite in nature.

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

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

they have some nice graphs where you see pictorially how much

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

Here's nuclear and here's renewable,

mostly hydroelectric and some burning wood.

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

They also have some nice diagrams that sort

of detail where, which things go to where.

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

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

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

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

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

Diagram.

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

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

to have ten billion people, which are coming, live

at US or Western standards, that implies something like

100 terrawatts of power necessary to make that happen.

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

And we have all this energy coming from

presumably renewables to last you know, for the millennia.

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

There's no precedent for it.

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

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

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

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

So, that looks pretty promising.

But take the next step down and we look at the

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

We're looking at 60 terawatts or there about.

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

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

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

and continuation of this under alternatives is not guaranteed.

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

There are problems and issues in the way.

That suggests we need to tackle this with

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

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

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

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

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

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

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

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

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

Your consumer choices matter.

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

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