This course is designed to introduce students to the issues of energy in the 21st century – including food and fuels – which are inseparably linked – and will discuss energy production and utilization from the biology, engineering, economics, climate science, and social science perspectives. This course will cover the current production and utilization of energy, as well as the consequences of this use, examining finite fossil energy reserves, how food and energy are linked, impacts on the environment and climate, and the social and economic impacts of our present energy and food production and use. After the introductory lectures, we will examine the emerging field of sustainable energy, fuel and food production, emphasizing the importance of developing energy efficient and sustainable methods of production, and how these new technologies can contribute to replacing the diminishing supplies of fossil fuels, and reduce the consequences of carbon dioxide release into the environment. This course will also cover the importance of creating a sustainable energy future for all societies including those of the developing world. Lectures will be prepared and delivered by leading UC San Diego and Scripps Institution of Oceanography faculty and industry professionals across these areas of expertise.
Biofuel and Water
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Из курса от партнера University of California San Diego
Our Energy Future
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Biofuel Production and Downstream Processing
Covers the chemistry of biodiesel, looks at the different thermochemical processes used to convert biomass to fuel, and examines renewable biogas. It also looks at the production process of algae biofuel, how and why nutrient utilization and recycling is important in biofuel production, and the relationship between biofuel and water.
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Dr. Stephen MayfieldProfessor of Molecular Biology
University of California San Diego
[MUSIC]
Hi, I'm Stephen Mayfield.
I'm Professor of biology and the director of the California
center for Algae Biotechnology at the University of California San Diego.
And today I'm going to tell you a
little bit about bio-fuels, water and the environment.
So, let's start with this slide, which is a
little complex, that looks at the global water footprint.
But, I show it to really show a couple of different points.
One is that, if we look at the entire globe, water is unequally distributed.
Some places get quite a bit of water, some not very much.
Most of the water on the planet, you will know, is saltwater.
2/3 of our planet is covered by ocean.
A very small percent of that, is actually fresh water.
And obviously, when we talk about biofuels, or when
we talk about energy water consumption for energy energy use.
It's actually the fresh water that matters.
Let's look at that in a different way.
Here's the total global water amount.
96% of that is in the oceans.
Only the small 2.5%, of that water is actually fresh water.
If we blow up that 2.5%, we see that again the vast majority
of it, is in glaciers and ice caps located on the two poles.
So, not water that we can take advantage of.
Ground water is 30% of that.
That's water we would have to mine or drill for.
And when we look at surface water, and other freshwater sources, that is only
1.3% of the 2.5%, so a fraction of the water that's on the planet.
If we now take this surface water and blow it up, we see that a fair amount
of that, is ice and snow, up in the
mountains, but this melts and becomes available to us.
Lakes are about 20%, and then if you look atmospheric,
biologic and then rivers are only 0.46% of the water.
So, in other words, although the planet is covered with water, fresh
water and fresh water that we have access to is really very limited.
So, where do we use water?
In the United States, the two biggest sources, are thermoelectric generation.
This is water that we use to build electric power
plants and irrigation, which by far dominates our water consumption.
After that comes domestic, and residential use, then public supplied industrial use.
Right aqua culture, mining and finally live stock.
But I think you can see that if you adress
these two, you'll address a lot of our concerns on water.
So, here's another way to look at that.
Here's the surface water, here's the surface water that's sailing.
Here's ground water, so mine water, and what
these arrows show is where it comes from and
where it goes to, and as you can see a very large percent of the surface water.
And a fair amount of service saline water go to thermo-electric cooling.
Now it should be pointed out that, this
water isn't consumed so we don't evaporate it.
What we do is we take water.
We use it to cool the electrical power plants, to make them
more efficient, and then that water is discharged back into the surface again.
So quite commonly, we'll pull the water off a river, use it to cool a power plant.
It goes back into the river, warmer than it was
before, but we haven't really consumed much of that water.
That does have environmental consequences, but not quite the same
as if we had consumed it or somehow fouled that water.
A fair amount of water goes to irrigation.
And again, the surface water and some, some
irrigation, some mined water, ground water, comes in use.
Most of that is consumed, or percolates into the ground.
Only a very small percent, actually goes back into, into rivers or or lakes.
So, I was certainly shocked by this, and I think
many people are, is that water is required to produce
all of our different foods, of course, all of our
different products, whether it's clothing, whether it's cars, you name it.
And the amount of water used for a specific food, can really vary greatly.
So, it takes about 200 liters of water to make a glass of milk.
Obviously most of that water is, irrigating the crops that get
fed to the dairy cows that then turn that into, to milk.
Wine?
About 120 ltrs.
One large hamburger, 2,400 ltrs of water.
That number is really big for a variety of reasons.
Partly because, we're growing grains we're growing grasses that we feed to beef cows,
they're relatively in-efficient at turning that into
protein and then all of the processing.
Whether it's the baking of the buns or
the hamburger, the shipping of it, you name it.
So, that's a pretty big number.
All right?
Obviously, these numbers vary greatly depending
upon where you are in the process,
name it, but I, I, I think this gives you a pretty good feel.
On how, how much water we have to use for things that
actually turn out to be a ver, relatively small consumption for us.
So, why is this important in bio-fuels, and what's the really big impact on that?
40% of our corn crop, is now used to make corn ethanol.
So, about 14 billion, 13.9 billion gallons per year.
Obviously, if you're at 40% of the crop.
And a third of our water is being used for irrigation.
I think you can arrive at the conclusion pretty quick, that a fair amount
of that is using to irrigate corn and that corn is using for ethanol.
So, direct water converted into fuel, okay.
Here, here starting in 2005 our ethanol production went way up.
Now, obviously, where you grow the corn, makes a
huge difference on how much water that you actually use.
And there are several different kinds of water.
And it depends upon where you're growing the corn.
So, if you're in the corn belt of Illinois
or Indiana or Iowa, or Kansas, or even Nebraska.
These are all the rain fed.
So, the grain water, that's rainfall.
So, that's water that falls on the ground that allows the corn to grown
that isn't taken out of a river or, or isn't mined out of the ground.
Okay.
However, in Nebraska and Kansas they also do corn irrigation.
That's the surface water is the blue water, so that would be taken out from
a lake or a river, and then the ground water, the mine water is in purple.
And if your out here in California, most of
the corn we produce here, we irrigate those crop.
So, obviously all of this water has a much
larger impact on water consumption than the rain water.
So, this is just a map of
the United States showing water requirements for irrigation.
I don't think it should come as a shock to anybody.
Out here in the west where you get
much less rainfall during the summer growing season, obviously
you have a much higher requirement for mined water,
for irrigation water, or for taking out of streams.
And then, over here is simply the amount of gallons per bushel of corn consumed.
And as you can see, that's a much higher consumption of water to produce a
bushel of corn in California, than to produce a bushel of corn in, in Illinois.
But, water is also used for other parts of the process as well.
Alright, so a big impact is the agriculture production that can
come in from rain fall that can come in through irrigation.
Some of the water used to grow the plants, some of this run off,
some of this goes for erosion or loss of in other forms of water loss.
Then after you produce the corn, you have
to go through the industrial process of turning
that corn into ethanol And so again, you
have water consumption in the industrial process as well.
So, what does that look like?
You get it in a couple of different places.
One, you have fresh water makeup to bring into the ethanol plant.
You then distill, after you've taken the corn, fermented it into ethanol.
It's a relatively small percent of ethanol in the water,
and you actually have to boil all the water off.
So, all of that water goes off as evaporation.
So, you lose a fair amount from that.
And you also have to put in, a fair amount of water into the process.
Just to get the entire thing going.
Because obviously the yeast that do the
fermentation, have to be in a water environment.
So total water demand, for a 50 million gallon per year plant, in terms of
gallons per hour you can see these numbers are pretty big, 5,280 gallons per hour.
The bottom line being the specific water demand comes up
to be 3.6 gallons of water for every gallon of ethanol.
In the pilot plant, in the, in the actual production.
Add on top of that, all the water that was required to grow it.
'Kay?
So, there's a fair amount of water that
is going to be used in any bio fuel production.
But, don't think that bio fuels are the
only energy, source that we have that requires water.
Every single one of them requires water.
A gallon of diesel requires about five gallons.
Or, or gasoline requires five gallons of
water, to produce one gallon of, of gasoline.
Natural gas, it's about five gallons per thousand cubic feet.
Coal, about 50 gallons per ton of coal process, and
electricity, as we showed before, is an enormous consumer of water.
Okay?
Water is also used in a new process called
fracking, and we'll talk about that in other lectures.
In, in, in fracking technology what you do is drill a, a gas or oil well,
and then you take water and under high
pressure squeeze it underground to frack the ground open.
This consumes a huge amount of water.
There are a 180, 000 wells in Texas alone.
400, 000 wells in the United States and
that equals five trillion gallons of water used.
To make these 400, 000 wells.
As many of you know, fracking is increasing at a dramatic pace.
That number is going to go up.
It's also interesting that many of the sites where we're
doing fracking, whether that's the Balkans, the Balkan shale in
North Dakota, or, or West Texas, or even now parts
of California also happen to be areas where water is scarce.
So, fracking sort of gets us on a double whammy on that one.
So, one of the problems has been, for many years,
that if you can grow plants with rainfall, that's renewable, right?
But, if you're having to have irrigation,
then you have something called ground water depletion.
So obviously, as you start to pull water out of the ground, you're pumping it
up to use for irrigation, that water comes and starts to deplete the water table.
This has significant consequences.
This picture always amazes me.
This is land subsidence from ground water pumping.
That means how much has the ground dropped because, I pumped the water out of it?
And what you see here is, this was the
ground level in 1925, this was the level in 1955.
And here it is when this picture was shot
in 1977, and it continues to go down today.
This happens to be the San Joaquin Valley, in, in California.
It has gone down nine meters from 1925 to 1977, and it still continues to go down.
Obviously, this is a significant issue.
Okay?
So, how are we going to improve this?
Well, one of the things that technology has done very well on.
As we've leveled the ground and smoothed it out.
We don't get nearly as much runoff from irrigation.
So, we've increased our efficiency about 50% on water utilization.
Also, from biotechnology, we have crops now that are much better at using water.
So, we've made dramatic improvements there.
So, technology is actually impacting this, and
making us much more efficient in water use.
We can also switch, to much more, to, to plants
that are much better at using water to produce biomass.
Here's just one example, algae.
Much more efficient at the water it uses compared
to how much energy you get out of it.
Same with things like switchgrass.
The final answer, I think, is going to be that we're
going to have to go to marine sources for these things.
This happens to be a picture of a natural
algae bloom, that happened in China during the Olympics.
But what is shows is that there are lots
of plants, that grow in marine saline waters that do
quite well at producing bio mass, and when we can
figure out how to use these to make bio fuels.
I think that'll greatly in, impact the use of water that we have to make energy.
Thank you very much for your attention, I hope
you've learned a little bit about water and bio fuels.
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