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.
Production Processes for Biofuels from Algae Part 1
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来自 University of California San Diego 的课程
人类能源的未来
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从本节课中
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.
与讲师见面
Dr. Stephen MayfieldProfessor of Molecular Biology
University of California San Diego
[MUSIC]
My name is Robert McBride.
I'm the Associate Director of Cultivation at Sapphire Energy, and today I'm
going to talk a little bit about
production processes for producing biofuels from algae.
And I think a really good place to start this conversation is to
talk about the, the demand for the fuel that you would be producing, right?
And so what I'm showing you here is a graph of, global oil consumption.
This is on a daily basis, so this is, you now, a million barrels of oil a day,
so right now, in 2015, we're consuming somewhere between
80 and 90 million barrels of oil a day.
And the graph also shows how that projected demand is,
is going to increase as as you go through time, right.
So, the world population is increasing, the demand for energy's
increasing but it turns out that our supply isn't increasing, right.
So, as you go through time and population increases and your demand
for energy increases, there's going to be this projected gap, illustrated by the red
box over here, and a lot of people are spending a lot
of time really thinking about how that gap is going to be filled.
And I put this data up here because I want to illustrate that any solution to, to
mitigating the challenge that is expressed by this
gap needs to be a solution that's scalable, right?
You need to be making multi million barrels of oil a day,
and it needs to be, it needs to be low cost, right?
You're dealing, with oil.
It's a commodity.
And typically, with commodities, you've got huge
volumes, and margins are very thin, right?
So, you've got to be able to compete in a, in a very
low cost environment, that's scalable, to be
able to tackle this challenge, completely, right?
And so, a lot of people think algae has the ability to do this.
And you know, an important component in understanding how we could
take algae to the scale is to, is to take lessons from
other activities that we, as humans, have scaled to the level
that we think is necessary to be able to impact fuel, right.
And one of those is agriculture and when you think about agriculture, it's scale.
Only four traits are important.
productivity, crop protection, harvestability, and and product profile.
And so, what I'm going to do, for the remainder
of this talk is, is walk through how each one of
these are, being thought of, and, and being, you know, implemented
in the production of algae for the, for, for bio fuels.
So, whe, when we're talking about productivity there is,
there is a number of different ways that we
can actually produce algae to generate biomass and the,
they're primarily broken down into two broad areas, right.
You can either have reactors that are open to the environment and, and
these are, you know, most often ponds that are just generally classified as
open reactors and then you've got reactors that are not open to the
to the environment, right, and these
are closed bio reactors or, or photobioreactors.
And so, you know, just to walk you through what
types of reactors these look like, we've got some open ponds,
over here, and, and these, are reactors that tend to be
less expensive, and they tend to be, easier to scale, right?
And here are some examples.
There are some of the, ponds that are used
to produce, beta kerotine with Dunaliella in, in Australia.
This whole size is around 700 hectares.
The largest of these ponds is around, 200 hectares.
So, you know?
You can scale this.
It's a very, sort of low engineered pond, right?
It just essentially has four walls.
It's filled up.
It relies on wind for mixing.
So a very sort of, at one end a very you know, unengineered system.
And then we have an example, on the bottom here, of a shallow cascade.
And the way algae is mixed in this system is it's
collected at the bottom, pumped up to the top and then gravity
allows it to run down over this cascade and this is
an example of a shallow cascade used in Czechoslovakia, production of chlorella.
The top right here we have some examples of Oswald ponds, so these are traditional
raceway ponds, so they are a circle and the water goes around it in a raceway
configuration developed in the 50s by, by Oswald,
actually a guy here from California and we've
got an example of some ponds out in
Calipatria being used for the production of Spirulina.
And then on the bottom right we have another Oswald pond.
however, the moat, form of motivation on this Oswald pond is jets.
And these, Oswald ponds are motivated by paddle wheels.
So just different ways to motivate them.
And this is an example of Oswald ponds from Australia where, raw
algae has them, and using them to produce nano crops as biomass.
So, again, the key thing with Oswalds are
that they are less expensive, they're sort of one
of the cheaper ponds in terms of the cost
for production, but they tend to be less productive.
And I'll go into a little bit more detail about the
advantages and disadvantages of the different types of ponds in a second.
But just to give you a, a feel for what closed systems look like, so
these are some examples of some photobioreactors
that are used for the production of algae.
Flat-plate photobioreactors have large illuminated surfaces
and allow high density of growth.
Right, there's a lot of light, so you can get really dense cultures.
Tubular photobioreactors, tubes that are horizontal
to the light, but will, horizontal to
the light, one of the challenges there is that the scale-up potential is limited.
And then you have column photobioreactors.
One of the great things about column photobioreactors is you
get a lot of head and so you were really
efficient mass transfer rates for, you know, gas, and you've
got pretty good control over a lot of the growth conditions.
But just to summarize these two, you know, these two sort of
primary ways of growing algae and some of their advantages and disadvantages.
This is a good table that gives you a high level overview of that.
So, to recap.
Raceway ponds.
The advantages of them.
Relatively cheap and you got low energy inputs.
The disadvantages are that you tend to get lower productivity out of these systems.
You need a lot of land to grow them
on, because of productivity is a little bit lower.
They're open ponds.
Crop protection is a huge issue.
You have to be able to manage it for this to be an effective
strategy and you don't get great mixing
which impacts light and carbon dioxide utilization, right.
So, definitely, advantages in terms of scalability and
cost, but some challenges in terms of productivity.
And then, as far as the photobioreactors go,
the advantages are that they're, you know, you get
really high productivities, you get really good efficiencies
in terms of light utilization, and nutrient use efficiencies.
They're compact.
You can get a lot of biomass produced on a small area.
But the challenges are that they're really expensive, some of them do have issues
with the phenotypes of algae that will actually grow on the edge of the walls.
Contamination is not as bad as the open ponds, but it's still an issue.
And quite a lot of them have issues with temperature control, right?
So, pros and cons, depending on what it is that you're
trying to make and, and what the cost is of the
product that you're trying to make may determine what are these,
which of these systems you would be interested in, in using.
okay, so, that talks a little bit about productivity, right and about how to
actually produce it, so that's describing the
fields that you could use for using algae.
And now another a sort of a trait that we're interested in is crop protection.
And as I mentioned, if you're in an open pond,
that's a little bit of a different scenario than closed photobioreactors.
And I'm going to focus on open ponds for,
for this section of the crop protection discussion.
But as you could imagine, with open ponds,
everything and anything that comes in on the wind
can actually end up in the pond, and a fraction of what ends up in the pond
is actually going to impact the productivity of the
algae and it could just you know, it could
be anything from taking a fraction of the
productivity, to actually causing the productivity to stop, right?
And so, a critical element in being able to, grow algae outdoors, is
you've got to manage the pests that will end up in a pond.
And looking to agriculture, again, for some of the lessons of sort of,
you know, taking an integrated pest
management approach, it's a fairly straightforward process.
You need to understand, of the fraction of the contaminants that
are in the pond, what fraction of those contaminants actually impact productivity.
And the way you do that is,
taking advantage of you know, [UNKNOWN], so there's
a lot of lab work involved but you know, assuming you find some organisms that
impact productivity, you've got to be able to track them and, and, then you, once
you contract them in the ponds, they get to a level that you don't like.
Then you have to be able to deploy a strategy
to manage them, and that cycle just repeats through time.
Right?
And so what I have here is an example of a common pest that
we see in Sapphire Energy, out at
our production facility in Las Cruces, New Mexico.
It's it's a chytrid fungus, well, it's not actually
a chytrid, it's a basil fungus related to chytrid, and
just to give you a quick overview of how it
works, so this is the motile stage of the chytrid.
It floats around in your pond.
Comes in on the wind.
Floats around in your pond.
Attaches to algae cells and then starts to develop
and use the algae to produce a lot of progeny.
And and those progeny will then get
released and repeat the cycle over and over.
And on the right here, we have a
scanning electromicrograph illustrating the same the same principle.
And this is done in collaboration with Pete Lecter at the University of Alabama.
And it gives you a great idea about what the life history is
of one these pests, but anyways, ways you manage these pests, and particularly
this pest, is you deploy a chemical, and in our case its a
pesticide you track the pest using real
time tracking devices such as quantitative PCR.
Pests get to a certain level, you deploy a strategy and the
pest goes down and then, you know, maybe it will come back again.
Just to give you an example in, in
the worst case conditions, with the right meteorological
conditions you know, from detection to a pond
being completely dead can take around 48 hours.
So, this is a real issue for open ponds.
You've really got to be able to manage it.
Different strategies for managing it, other than chemicals.
There are mechanical mechanisms for managing crop protection such as pumps.
They tend to work well on larger grazing microorganisms such as such as rotifers.
The pumps will actually physically disrupt those organisms and then you
can deploy biological strategies which
will take advantage of trophic interactions.
For example, deploying rotifers intentionally.
Because they may preferentially feed on the enemy of your of your algae, right?
So the enemy of my enemy is my friend.
That's a strategy that you can employ, and
that has been employed at scale fairly effectively.
You've got the algae, you've grown it in these outdoor ponds,
you've got a lot of biomass, you've managed to keep it
from dying by crop protecting it well, and the next thing
you have to do is get that algae out of the water.
And this actually is a, is a fairly energy, energetically-intensive step.
And they're you can do this in, in a number of different ways.
And what I'm illustrating here is, four of the main
ways that people used to separate algae from the water.
You have a centrifuge, uses gravity.
You have filters which use a size differential.
You can use flocculation, which either involves just letting organisms settle
naturally, or putting a polymer into the the culture, which will make
them aggregate and then settle out, or you can use the dissolved
air flotation, which typically is used in conjunction with, with a polymer.
And again, as I mentioned this can be a single step process.
Or you can use these technologies in combination
with one another to actually get more concentration.
So, for example, you could harvest algae using dissolved air flotation,
and then take that product and concentrate it using a centrifuge.
And that way, you don't use the centrifuge as much,
because you're working on a much smaller amount of, of biomass,
concentrating down a smaller stream than you would if you
were just trying to use a centrifuge on an open pond.
So, you've got that biomass and the next step
is to take that biomass and convert it into energy.
And with algae biomass, there's actually a lot
of options out there that people have done
a lot of work on understanding how to
actually convert this this, this biomass to energy.
But essentially, it's broken down into two areas.
Thermochemical conversion and biochemical conversion,
and in thermochemical conversion there's gasification,
which will produce syngas, thermochemical
liquefaction, which will bio oil, pyrolysis.
Which produces bio syngas and charcoal, and then direct combustion
to produce heat, which will obviously be used to produce electricity.
And then, as far as biochemical conversion, anaerobic
[UNKNOWN] will produce methane and hydrogen you can
ferment it to get ethanol and you can
also photobiotically produce hydrogen and that's another strategy, so.
Lots of options for producing, energy from algae.
But the key thing with any of these strategies, is,
you want to make sure that, what you're doing makes sense, right?
And, and, what do I mean by make sense?
The barrel of oil or the barrel of energy that you are
producing from algae needs to, consume
less energy than it actually produces, right?
And so what we have, over here, is a graph
with a, an energy return on investment, and greenhouse gas emissions.
And I just want to orient you quickly.
If the number's one, what that means is that you're breaking even, right?
You're producing as much energy as you'll consume during the production process.
And so, typically, when you're making energy, what you want to be
doing is you want to be making more energy than you're consuming, right?
You want to be contributing to the system and not just breaking even.
And so this is a paper that was recently put out where we took data
from Sapphire took data from its pilot-scale
facility out in Las Cruces and Columbus, New
Mexico, and used that data to make
projections about what the earned return on inv,
on investment would be, energy return on investment
would be, when we had our full-scale operation.
And as you can see, we've got gasoline over here, right?
So gasoline has a, has a, has a high EROI.
Which means it's you know, gets a lot more energy out
of it than you put in to actually getting that gasoline.
Some other options, second generation biofuel options, don't have a
great EROI, but algae actually, with the data that we've generated
from our, from our, production side, shows that has a
really good EROI and also has relatively low greenhouse gas emissions.
So, when we get it to scale it's going to
be a great solution for you know, for that gap
that I talked about in the beginning of the presentation,
that energy gap that we got coming down the road.
