1. Daniel Urban
December 10, 2015
Energy Final Project
Introduction
A
sustainable
energy
future
is
a
critical
need
that
must
be
achieved
for
multiple
reasons.
These
include
but
are
not
limited
to:
having
energy
available
for
the
growing
population
of
the
world
while
fossil
fuel
stores
are
being
depleted,
creating
energy
that
produces
less
harmful
emissions,
and
having
energy
security
knowing
that
we
will
have
a
way
to
produce
energy
that
doesn’t
rely
on
other,
possibly
hostile
countries.
A
sustainable
energy
future
is
not
something
that
will
happen
over
night.
We
are
in
what
is
called
a
transition
period.
This
period
is
characterized
by
the
efforts
to
optimize
our
use
of
remaining
fossil
fuel
supplies,
while
putting
money
into
researching
and
developing
more
renewable-­‐based
options.
Some
key
advances
and
strategic
implementation
of
technology
will
need
to
be
made
during
this
transition
period
to
ensure
that
a
sustainable
energy
future
is
achievable.
This
report
goes
over
the
following
nine
technologies
that
support
the
current
energy
supply
system,
and
may
contribute
to
the
long-­‐term
sustainable
energy
future.
Technologies addressed:
1. Grid-connected energy storage
2. Fuel cells
3. MHD
4. Thermoelectric generators and refrigerators
5. Solar photovoltaic
6. Solar thermal
7. Wind
8. Nuclear fission
9. Nuclear fusion
These
technologies
are
briefly
described
and
then
analyzed
for
the
benefits
and
drawbacks
that
they
each
have.
A
brief
role
for
the
future
is
also
included
at
the
end
of
each
technology’s
section.
Finally,
a
summary
of
my
thoughts
for
the
sustainable
energy
future
is
on
the
last
page
of
the
report.
This report has been written to show the reader that there can be a fairly clear path along the
transition towards a sustainable energy system. It also allows the reader to understand the
inherent benefits and drawbacks to each of the current technologies that are supporting the
energy system today.
None of these technologies by themselves are the answer, but a combination of them can provide
a solid platform with which we can shape the energy future. Noted too is the timeline of 100
years. A lot of the information in this report is based off of present technology, but most likely
will be surpassed by advancements made over time. These thoughts are expressed throughout the
report so that we don’t limit ourselves to only the knowledge we have currently.

2. Grid – Connected Energy Storage
Grid – connected energy storage is made up of devices used to store electrical energy on a large
scale within a power grid. Energy is stored in these devices when production exceeds
consumption, and is returned to the grid when energy consumption exceeds base load
production. This technology primarily enables a sustainable primary energy source to be better
utilized by storing the excess energy produced by intermittent energy producing technologies to
be used when there is a need.
There are six types of grid-connected energy storage that will be evaluated here. These include:
air, batteries, hydrogen, hydro, superconducting magnets, and flywheel. There will be paragraphs
going over the pros and cons of each of these technologies followed by a few paragraphs
analyzing the technology of grid-connected energy storage as a whole.
Compressed air energy storage (CAES) is the first technology to be looked at. Compressed air
energy storage starts with air being compressed and stored in areas like underground caverns.
When electricity is needed, the air is heated and expanded through an expansion turbine driving a
generator for power. One of the cons of this type of storage is that it needs a small amount of
fossil fuel to compress the air and to heat the air. This also means that it creates CO2 emissions to
work. Possible ways to mitigate this is to use heat rejection from a renewable system like a fuel
cell. Another disadvantage of the system is that you must have a lot of storage underground,
which requires a large capitol investment as well as suitable land. This could disturb ecosystems,
and could damage the surrounding if an accident happened. The final con is that an accident in
this system is called a catastrophic tank rupture, which can damage anything around it. The
advantages of this storage technique are that its round trip efficiency is around 70% and the air is
easily accessible.
Another air energy storage technique is liquid air. Liquid air is created through compressing and
cooling the air until it is liquid. When it is needed, the stored liquid air is expanded through a
turbine to create electricity. Because of the need to cool the air so low, the round trip efficiency
is at about 25% but projections have been made that it could increase to around 50%. Currently
only cryogenic distillation of air is commercially viable technology for large-scale energy
storage. The pros of the system include safer storage, and the lack of energy input when energy
is needed. The current low round-trip efficiency is a major disadvantage of this storage
technique.
Batteries are the most well known type of energy storage. There are some general cons to
batteries, which include relatively high prices, high maintenance costs, in some cases being
flammable, use toxic materials most of the time, have low energy density, and have limited life
spans due to pure chemical crystals that form inside the cells during charging and discharching
cycles. These crystals grow large enough to distort the battery and short out the cells. The
advantages of battery storage include that they are clean, relatively efficient, provide stored
energy instantaneously, do not need special geological/geographical requirements, can easily
integrate into the grid, rarely need expensive rare metals, have been tested extensively, and have
a large amount of funding going into research and development.
Hydrogen storage is comprised of compressing or liquefying hydrogen, storing it, and then
converting it back to its original state while collecting the electrical energy or heat produced.

3. Hydrogen has the advantage of being a high-density fuel. On the downside, you must either
reform natural gas with steam or use electrolysis of water to get the hydrogen needed.
Electrolysis needs high temperature and pressure, which unless supplied by something like a
nuclear plant, are unrealistic. Efficiencies are generally low due to the energy required to
produce the hydrogen. Also, needed equipment and resources include an electrolysis plant,
compressors or liquefiers, storage tanks, and underground caverns or salt domes to store all of
the tanks.
Pumped-storage hydroelectricity is the most utilized grid-connected energy storage in the
world currently. It is used to even out the daily generating load by pumping water to a high
storage reservoir during times of excess production. When the demand is more than the
production, hydroelectric generation is used with the water that was pumped earlier. This energy
storage method has the benefit of being fast in response. It also has 70-85% efficient and is the
most cost-effective form of large-scale power storage currently. It is good for variation in
demand. On the downside, it needs a very specific geography of two lakes near each other that
are separated by a considerable vertical distance. It also has the ability to negatively impact
animal life in these water reservoirs, and the ecosystem around when you drill out part of the
earth to put the hydroelectric generator and other parts needed.
Superconducting magnetic energy storage (SMES) systems store energy in the magnetic field
created by the flow of current in a superconducting coil. The systems have super high efficiency
around 95% with losses from the inerter/rectifier. This is the best efficiency out of any of the grid
connected energy storage systems. Once the coil has been charged, the current will not decay and
the magnetic energy can be stored indefinitely. There is however a large energy requirement for
refrigeration, so short duration energy storage is better for this technology. Also,
superconducting coils of this size are very expensive. Finally, there is the need for a large
amount of infrastructure and land for the magnet and skilled technicians who can run it and
repair it when needed.
The final energy-storage technology to analyze is the flywheel. The flywheel is made up of a
heavy rotating disc that is accelerated by an electric motor when electric power flows into the
device. When the flow of power is reversed, electricity is produced. The method is very
expensive because to get low friction, the flywheel must be in a vacuum and must use magnetic
bearings. Due to the fact that larger flywheel speeds allow for greater storage capacity, the
system is better suited for load leveling, and is not feasible for general storage applications. This
is a very limited technology, but is successful for specialized applications.
When looking at grid-connected energy storage as a whole there are some consistent advantages
and disadvantages. One of the biggest advantages is that it will allow intermittent renewable
energy sources to be utilized effectively. It also greatly enhances the grid reliability by providing
back ups. It will help to fuel the transition by integrating renewable and fossil fuel sources
together. When looking at the cons, the glaring fact is that each has its own issues that are yet to
be answered. None of the technologies are perfect, but thankfully large amounts of money are
being poured into R&D. Also, there is the need for a large amount of new infrastructure to
implement any of these technologies.
The future of energy conversion will have grid-connected energy storage as a major contributor.
To make the transition from fossil fuels to a sustainable energy system will require energy
storage. Currently, pumped-storage hydroelectricity is the major player of this technology, but I
believe that batteries will eventually be the golden child of this technology. It is only a matter of

4. time before the billions of dollars being poured into this technology will pay off. Batteries have
the efficiency pay off, the immediate energy, and the ease of integration on both large scale and
small-scale platforms to make a huge difference in the path to a sustainable energy future. Other
storage technologies like hydroelectricity, compressed air and hydrogen, and flywheel will be
used where they can be applied best, but I still believe that batteries will eventually make the
largest impact if we are looking at this from a 100-year standpoint.

5. Fuel
Cell
Technology
Fuel
cells
are
devices
that
convert
the
chemical
energy
of
different
fuels
directly
into
electricity
by
utilizing
chemical
reactions
of
positively
charged
hydrogen
ions
with
oxidizing
agents.
There
are
many
varieties
of
fuel
cells,
but
they
all
work
in
the
same
general
manner.
They
also
are
all
made
up
of
three
segments,
which
are
the
anode,
the
cathode,
and
the
electrolyte.
Four
of
the
main
types
of
fuel
cells
are:
proton
exchange
membrane
fuel
cells
(PEMFC),
phosphoric
acid
(PAFC),
solid
oxide
fuel
cells
(SOFC),
and
molten
carbonate
(MCFC).
PEMFC,
PAFC,
and
SOFC
are
technologies
that
enable
a
sustainable
primary
energy
source
to
be
utilized,
while
MCFC
is
able
to
extend
the
availability
of
existing
finite
energy
resources.
There
are
pros
and
cons
to
each
of
these
fuel
cells,
and
also
pros
and
cons
of
the
overarching
fuel
cell
technology.
The
following
paragraphs
will
go
in
depth
about
the
four
fuel
cell
types
above
and
the
paragraphs
that
remain
will
look
at
the
technology
as
a
whole.
The
first
technology
to
focus
on
is
the
proton
exchange
membrane
fuel
cell
(PEMFC).
These
fuel
cells
are
distinguished
by
their
low
temperature
and
pressure
ranges.
These
attributes
are
positives
of
the
technology
because
they
keep
from
high
temperature/pressure
fatigue
of
the
materials.
The
PEMFC
technology
also
has
a
fast
response
time.
This
means
that
it
is
viable
for
many
applications
where
quick
response
is
a
necessity.
Currently,
this
technology
is
looked
at
primarily
for
transportation.
PEMFC
have
efficiencies
in
the
range
of
40-­‐60%,
which
is
pretty
respectable.
This
efficiency
is
made
up
solely
of
electricity
output.
PEMFCs
also
have
a
specialized
polymer
electrolyte
catalyst.
This
is
a
con
to
the
technology
since
it
is
made
using
platinum,
which
makes
the
fuel
cell
very
expensive.
Nearly
half
of
the
fuel
cell
cost
is
attributed
to
the
catalyst.
To
overcome
this,
the
platinum
need
must
either
be
reduced
or
a
new
catalyst
material
must
be
found.
Increasing
the
catalytic
activity
of
the
platinum
is
one
way
of
achieving
the
reduction
in
platinum.
In
addition
to
cost,
water
and
air
management
are
design
problems
for
the
PEMFC.
The
membrane
of
the
cell
must
be
hydrated
at
all
times.
If
the
membrane
dries,
resistance
will
build
and
the
cell
will
crack.
If
the
cell
is
flooded,
the
reactants
wont
reach
the
catalyst
and
the
reaction
will
stop.
Methods
like
electro
osmotic
pumps
are
being
developed
to
help
fix
this
issue.
Finally,
durability
is
an
issue
for
the
PEMFCs
because
they
need
to
operate
at
a
wide
variation
of
temperatures
for
many
hours.
The
current
technology
for
PEMFCs
does
not
achieve
the
life
span
requirements
of
current
cars
or
stationary
energy
converter
requirements.
The
next
fuel
cell
technology
to
focus
on
is
the
phosphoric
acid
fuel
cell
(PAFC).
PAFCs
use
a
non-­‐conductive
electrolyte
to
pass
positive
hydrogen
ions
from
the
anode
to
the
cathode.
The
technology
works
best
in
a
temperature
range
from
150-­‐200
degrees
Celcius.
The
efficiency
of
this
technology
increases
to
the
80%
range
if
the
heat
of
the
system
is
used
for
cogeneration.
The
split
between
electrical
output
and
heat
output
is
about
50/50
for
the
above
efficiency.
The
first
con
of
the
PAFC
is
that
it
again
uses
platinum
as
its
catalyst
so
that
the
hydrogen
ionization
rate
is
high.
This
makes
the
technology
expensive
like
the
PEMFC.
In
addition,
the
technology
uses
acidic
electrolytes.
These
make
up
another

6. negative
for
the
system
because
they
lessen
the
durability
and
life
span
of
the
cells
by
increasing
the
corrosion
and
oxidation
of
components
inside
the
cell.
Solid
oxide
fuel
cells
(SOFC)
are
characterized
by
a
solid
ceramic
material
as
the
electrolyte.
They
have
the
advantage
of
being
able
to
be
made
in
a
variety
of
shapes
and
are
not
relegated
to
the
flat
plan
configuration
of
the
other
fuel
cells
types.
They
also
have
the
benefit
of
being
able
to
be
run
on
a
variety
of
fuels,
but
the
fuel
must
contain
hydrogen
atoms
for
the
reaction
to
work.
SOFC
technology
requires
super
hot
operating
temperatures
in
the
range
of
800
–
1000
degrees
Celsius.
The
benefit
of
these
high
temperatures
is
that
there
is
no
need
for
platinum
in
the
catalyst
making
the
system
cheaper.
Another
benefit
of
the
high
temperature
is
that
the
waste
heat
of
the
system
could
be
used
for
cogeneration,
which
can
bump
the
efficiency
into
the
80%
range.
The
negative
of
the
hot
temperature
is
that
carbon
dust
can
build
up
on
the
anode,
which
lessens
the
performance
of
the
whole
fuel
cell.
Another
negative
of
the
technology
is
that
there
is
a
slow
start
up
time
due
to
the
ceramic
that
is
used
as
the
cell
substrate
in
addition
to
the
super
high
temperatures
necessary
for
the
system
to
work.
This
keeps
the
technology
from
any
automobile
or
other
quick
response
usages.
Finally,
SOFCs
are
currently
in
early
development
and
have
not
been
refined
enough
for
mass
production.
They
have
a
promising
future
if
developed
correctly,
but
are
not
viable
now.
The
final
fuel
cell
to
analyze
is
the
molten
carbonate
fuel
cell
(MCFC).
MCFCs
use
liquid
lithium
potassium
carbonate
salt
as
the
electrolyte.
The
system
converts
fossil
fuels
to
a
hydrogen-­‐rich
gas,
which
reduces
the
need
for
external
hydrogen
production.
The
system
has
the
benefit
of
using
readily
available
fuels
like
natural
gas,
biogas,
and
gasses
from
coal.
MCFCs
have
a
resistance
to
impurities
like
the
carbon
build-­‐up
on
anodes.
The
system
also
has
impressive
efficiencies.
The
electrical
output
efficiency
is
up
to
50%,
but
can
rise
to
the
80%
range
is
used
for
combined
heat
and
power.
The
negative
of
these
fuels
is
that
the
reforming
process
of
the
system
creates
CO2
emissions.
Another
negative
of
the
system
is
that
the
high
operating
temperatures
needed
for
the
system
create
a
slow
start-­‐up
time
for
the
cell.
Also,
the
cells
have
short
life
spans
due
to
the
corrosion
of
the
anode
and
cathode
in
response
to
the
high
temperatures
and
the
carbonate
electrolyte.
There
are
some
common
themes
when
observing
the
benefits
and
disadvantages
of
fuel
cell
technology
as
a
whole.
The
benefits
of
fuel
cell
technology
include
relatively
high
efficiency.
PEMFC
has
electrical
output
efficiency
between
40-­‐60%,
while
the
other
three
systems
can
reach
around
80%
efficiency
if
used
for
combined
heat
and
power.
Other
than
MCFC,
the
systems
are
carbon
free
when
using
H2
and
O2.
The
first
three
systems
above
enable
a
sustainable
primary
energy
source
to
be
better
utilized,
while
MCFCs
extend
the
availability
of
existing
finite
energy
resources.
These
systems
can
run
continuously
as
long
as
fuel
is
supplied
and
can
provide
base
load
power
that
can
be
used
in
conjunction
with
renewable
technology.
The
systems
have
no
moving
parts,
and
are
easily
scalable
to
meet
the
needs
of
the
public
or
industries.
In
addition
to
the
scalability,
the
system
is
also
well
suited
for
distributed
generation,
which
also
makes
it
great
for
meeting
the
needs
of
the
surrounding
area.
Finally,
and
most
notably
is
the
fact
that
they
can
run
on
water,
which
is
an
easily
accessible,
renewable
resource.
The
disadvantages
of
the
technology
is
that
most
of
the
fuel
cells
require
expensive
materials
like
platinum
as
cathode
and
anode
material.
Service
life
and
durability
are
also
a
big
issue
especially
when
considering
the
high
temperature
variants.
Contamination

7. sensitivity
of
the
low-­‐temperature
variants
provides
a
problem
for
service
life
as
well.
Currently,
hydrogen
is
not
easily
accessible
in
large
quantities,
and
infrastructure
for
making
it
would
need
to
increase
greatly
if
large-­‐scale
fuel
cell
technology
is
ever
to
become
a
large
contributor
to
the
energy
production
as
a
whole.
Finally,
it
is
predicted
that
if
battery
technology
advances
enough,
fuel
cell
technology
will
become
irrelevant.
My
thoughts
on
the
future
role
of
fuel
cells
are
mixed.
I
believe
that
MCFC
technology
could
help
in
the
transition
time
to
extend
the
use
of
fossil
fuels
since
the
combined
heat
and
power
efficiency
is
around
80%.
In
addition,
I
believe
that
SOFCs
have
the
ability
to
become
very
useful
for
the
renewable
energy
future
if
cogeneration
is
a
need.
The
carbon
dust
build-­‐up
issue
will
need
to
be
mitigated
first
though
since
longevity
would
become
an
issue.
Also,
PEMFCs
are
a
viable
future
for
renewable
base
load
if
electricity
output
is
the
main
concern.
There
needs
to
be
a
lessened
amount
of
platinum
used
to
make
it
affordable
enough,
and
durability
will
need
to
be
increased
substantially
for
PEMFCs
if
they
are
ever
going
to
make
a
huge
impact.
These
technologies
have
promising
futures
in
the
transition
and
long-­‐term
energy
future
if
critical
advances
are
made.
The
tricky
part
to
this
is
that
there
would
need
to
be
a
lot
of
infrastructure
change
for
large-­‐scale
fuel
cell
energy
production
to
occur.
Getting
everyone
on
board
with
the
switch
as
well
as
getting
lots
of
research
money
to
improve
the
technology
enough.

8. Magnetohydrodynamic
Generators
A
magnetohydrodynamic
generator
is
a
device
that
transforms
thermal
energy
and
kinetic
energy
into
electricity.
A
conductor
is
moved
through
a
perpendicular
magnetic
field
to
generate
an
electric
current.
This
is
a
system
that
extends
the
availability
of
existing
finite
energy
resources
because
it
relies
on
fossil
fuel
processes
before
and
after
the
system.
There
are
three
main
types
of
MHD
generators.
They
are
the
Faraday
Generator,
the
Hall
Generator,
and
the
Hall
Effect
Disc
Generator.
Since
the
last
of
these
three
is
superior
to
the
other
two,
it
will
be
focused
on
below.
The
Hall
Effect
Disc
Generator
uses
an
electrically
conductive
fluid
flowing
between
the
center
of
a
disc
with
a
duct
wrapped
around
the
edge.
This
system
does
not
suffer
from
the
Hall
effect
because
the
Hall
effect
currents
flow
between
the
ring
electrodes
near
the
center
and
the
periphery.
This
avoids
the
electrodes
that
are
conducting
the
electricity.
This
is
better
than
the
regular
Hall
generator
because
the
Hall
generator
shorts
the
middle
electrodes
making
the
system
very
sensitive
to
load.
If
the
load
changes
too
much,
the
flow
will
misalign
and
the
effect
won’t
continue
to
be
mitigated.
The
disc
generator
also
benefits
from
the
magnet
being
smaller
due
to
the
fact
that
it
can
be
much
closer
to
the
fluid
in
this
system
design.
These
system
advantages
make
it
the
most
efficient
MHD
generator
scheme.
Even
so,
efficiency
is
usually
well
under
30%.
MHD
generators
have
common
advantages
and
disadvantages
across
the
board.
They
have
the
Carnot
advantage
because
you
can
put
in
hotter
temps
than
you
can
for
a
turbine’s
inlet.
Even
so,
the
high
resistivity
of
the
fluid
and
walls
of
the
system
take
a
lot
of
this
advantage
away.
They
also
have
no
moving
parts,
which
increases
reliability
over
time.
They
can
be
implemented
as
a
topping
cycle
by
using
the
exhaust
to
heat
the
boilers
of
a
steam
plant.
This
can
achieve
a
combined
efficiency
of
around
60%.
Efficiency
of
the
system
itself
also
increases
with
larger
size
since
you
will
get
a
better
volume
to
surface
area
ratio.
You
can
also
reverse
the
system
if
needed.
The
disadvantages
of
this
technology
are
pretty
glaring.
First,
the
system
relies
on
fossil
fuel
powered
technology
before
and
after.
In
addition
to
this,
the
efficiencies
of
combined
cycles
using
natural
gas
turbines
into
Rankine
cycles
are
comparable
in
efficiency
and
are
also
much
cheaper.
Also,
electrodes
suffer
from
electrochemical
attack
unless
coal
is
used
before,
which
would
allow
for
mineral
slag
to
protect
the
electrodes
from
damage.
Finally,
parasitic
losses
develop
to
power
the
electromagnet,
seed
material
is
expensive
and
must
be
retrieved
later,
and
rare
metals
such
as
platinum
are
usually
needed
to
cap
the
electrodes.
Looking
at
the
disadvantages
compared
to
the
advantages
of
this
technology
make
me
think
that
MHD
generators
will
not
be
a
significant
part
of
the
sustainable
energy
system
in
100
years
unless
some
major
breakthroughs
happen
that
allow
the
efficiency
to
get
substantially
better.
If
this
happens,
this
technology
could
be
used
in
the
transition
period
to
extend
the
effect
of
the
limited
fossil
fuel
resources
we
have
today.

9. Thermoelectric
Generators
and
Refrigerators
The
thermoelectric
generator
(TEG)
is
a
device
that
converts
heat
directly
into
electrical
energy
using
the
Seebeck
effect.
The
system
acts
like
a
heat
engine,
but
with
no
moving
parts.
This
technology
can
both
extend
the
availability
of
existing
finite
energy
resources
and
enable
a
sustainable
primary
energy
source
to
be
better
utilized.
This
is
because
it
can
be
put
at
the
exhaust
of
either
a
fossil
fuel
burning
engine
or
a
renewable
energy
energy
conversion
device
to
create
more
energy.
All
it
needs
is
an
input
of
power.
The
thermoelectric
refrigerator
can
do
both
as
well
depending
on
what
is
creating
the
current
that
it
is
powered
by.
Two
devices
are
in
this
category.
These
are
the
thermoelectric
generator
and
refrigerator.
The
thermoelectric
generator
uses
waste
heat
to
produce
power.
It
acts
like
a
heat
engine,
but
is
less
bulky
and
has
no
moving
parts.
It
is
also
small,
does
not
need
maintenance,
and
is
highly
reliable.
The
best
application
is
when
the
temperature
difference
between
the
hot
and
the
cold
is
small.
Finally,
it
is
Carnot
limited
like
a
heat
engine.
Unfortunately,
there
are
a
lot
of
disadvantages
to
this
technology.
First,
the
TEG
is
more
expensive
and
less
efficient
than
a
heat
engine.
The
efficiency
of
the
system
is
usually
under
10%.
Also,
they
tend
to
develop
mechanical
fatigue
due
to
the
large
number
of
cycle
at
high
temperature.
The
thermoelectric
refrigerator
or
Peltier
Refrigerator
has
a
DC
current
flow
through
the
device,
which
heats
up
one
side
and
cools
the
other.
The
hot
side
is
attached
to
a
heat
sink
that
keeps
its
temperature
constant,
while
the
other
side
gets
colder.
The
system
has
advantages
of
the
vapor-­‐compression
refrigeration
cycle
because
it
has
no
moving
parts
or
circulating
fluid,
is
smaller,
has
a
very
long
life,
and
is
flexible
in
shape.
Even
though
these
seem
like
big
advantages,
the
high
cost
and
poor
efficiency
of
the
technology
hold
it
back
from
being
chosen
over
the
usual
refrigeration
cycles.
I
do
not
believe
either
of
these
two
technologies
will
make
a
large
impact
on
the
sustainable
energy
future.
TEGs
could
be
used
in
the
transition
period
to
extend
the
energy
we
get
out
of
fossil
fuels
or
in
the
energy
future
by
squeezing
every
efficiency
point
out
of
the
exhaust
of
some
techniques
like
fuel
cell
energy
production.
Thermoelectric
refrigerators
could
also
make
a
difference
in
refrigeration,
but
efficiency
would
need
to
increase
substantially.
Overall,
this
technology
does
not
seem
to
be
a
game
changer
in
my
mind
100
years
from
now.

10. Solar Photovoltaic
Solar photovoltaics (PV) is the method of converting solar energy into DC electricity using
semiconducting materials that have the photovoltaic effect. Solar panels are composed of many
small solar cells to create solar power. This system enables a sustainable primary energy source
to be better utilized. PV is currently the third most producing renewable energy source behind
hydro and wind power. PV is a technology that enables a sustainable primary energy source to be
better utilized.
PV solar cells have a lot of great advantages. They make use of an inexhaustible and abundant
fuel supply. In addition to the fact that there is an endless supply of fuel, the energy is clean.
There is no need to create emissions when you can convert the solar energy directly into DC
electricity. It is available practically everywhere and does not need any specialized geographical
features. There are no moving parts required, which makes them very reliable without the need
for much maintenance over their lifetime. There is no noise pollution compared to technologies
like wind power. Excess heat from the cells could be used for cogeneration if needed. It also
encourages the transition from centralized to distributed power generation. This has major
benefits including less transmission losses, less effect from acts of terrorism, less money spent on
utilities since houses can sell extra energy produced to the utility companies, and huge steps
towards a sustainable energy future. Finally, subsidies from the government are pushing the
technology forward so that it is viable for people to adopt.
There are cons to this technology as with all technologies talked about in this report. First, and
most notably, it is an intermittent source. This means that there will be the need for base load
technology to sustain the grid, and it also means that storage technology like batteries must
become more viable for PV technology to reach its maximum potential. There are relatively high
costs for buying the cells even though it is going down quickly. Also, production of the PV cells
takes a lot of energy, uses fossil fuels, and produces emissions. The payback time can be as much
as 5-15 years! The efficiency goes down when it is colder outside. It requires an inverter to
produce AC current, which is another loss that the system will encounter. In addition, large
amounts of space are required for the systems since the technology is driven by economics, not
efficiency. Finally, there is still fairly low efficiency of the cells. The market average is under
20% efficiency.
I do believe PV cells will be a large contributor to the sustainable energy system in 100 years.
The fact that the sun is an inexhaustible, clean fuel makes it very attractive as well as the fact that
the government has bet on it by subsidizing it so heavily also makes it an attractive option.
Couple these with the billions of dollars in research funding for the technology, and it has a
bright future. This bright future will be utilized at both the community level and the industrial
level. Families will continue to adopt the technology as the benefits continue to rise, while large-
scale solar farms will continue to fill unused space in an effort to create more renewable energy.
Even though all of these things are working to the advantage of this technology, it is not a
compete solution for the future. This technology relies on the advance of storage devices like
batteries to improve substantially so that the excess energy produced can be stored and used
efficiently. Also, base load systems will still need to be in place since this is an intermittent
technology. Even so, it is bound to make a huge difference in the landscape of the future
sustainable energy system.

11. Solar Thermal
Solar thermal technology harnesses solar energy to generate thermal energy or electricity. This
technology can be used for both residential and industry use. Solar thermal is a technology that
enables a sustainable primary energy source to be better utilized. It does this by taking advantage
of the inexhaustible fuel that the sun provides and turns it into usable power.
Solar thermal is broken down into two main types. These types are solar heating and cooling, and
concentrated solar power. Solar heating and cooling uses solar panels that collect heat and use
the heat directly for applications like hot water, space heating, and air conditioning. The second
type is concentrated solar power which concentrates solar collectors on a point which creates an
intense beam that is shone on a vessel or pipe containing a fluid which is converted to steam to
drive a conventional thermal power plant.
These systems are fairly inexpensive, and pay for themselves quickly. They do not require as
much energy input as PV cells, and use less exotic materials. They are on the order of 3 times as
efficient as PV cells. They can be used for either heating or cooling. Cooling is done through the
use of the absorption cooling cycle. Solar heating energy is available when you most need it,
which is during the day. This system, like PV systems, encourages distributed power generation
with less reliance on the large-scale grid. The system is simple and low-maintenance with a long
life expectancy. In addition, the operating costs of the system are near zero. Finally, these are
modular systems with high efficiency.
The
downside
of
the
technology
begins
with
the
fact
that
they
haven’t
caught
the
attention
that
PV
cells
have.
This
means
that
there
aren’t
as
many
subsidies
out
there
to
incentivize
the
purchase
of
these
systems.
This
doesn’t
meant
that
they
won’t
eventually
get
the
face-­‐
time
that
they
deserve,
but
currently
they
are
fairly
in
the
dark
when
it
comes
to
public
knowledge.
Solar
cooling
systems
are
currently
complex
and
expensive
and
solar
heaters
are
more
than
conventional
water
heaters.
This
must
get
better
if
the
technology
is
going
to
make
any
market
step
forward
in
terms
of
market
share.
As
with
all
solar-­‐based
systems,
the
fuel
is
intermittent
and
low
in
energy
density,
which
means
that
it
must
be
coupled
with
a
storage
device,
and
have
a
base
load
for
a
back
up
system.
These
systems
only
create
heat
and
produce
no
electricity.
Instillation
costs
can
be
high
and
also
unavailable
in
a
lot
of
the
US.
These
systems
are
only
really
effective
for
small-­‐scale
applications
currently.
I
do
believe
that
these
technologies
can
play
roles
in
the
sustainable
energy
future.
For
solar
heating
and
cooling,
I
believe
that
coupled
with
PV
cells
and
improved
batteries,
homes
can
become
almost
self-­‐sustainable.
The
solar
heating
and
cooling
could
take
care
of
the
air
temperature,
while
the
PV
cells
could
take
care
of
general
electrical
use
and
store
the
excess
for
use
during
the
night.
As
said
many
times
already,
batteries
are
crucial
to
the
success
of
this
technology.
Even
so,
there
would
still
need
to
be
backup
to
the
grid
just
in
case
of
an
emergency
or
if
there
wasn’t
enough
sunlight
to
power
the
home
throughout
the
night.
This
will
only
happen
if
good
subsidies
help
people
to
see
that
adoption
of
this
technology
is
worthwhile
like
has
been
done
with
PV
cells.
The
houses
could
run
into
issues
with
space
on
their
roof,
so
efficiency
might
also
come
into
play
eventually.
Decentralizing
the
grid
using
the
combined
solar
technologies
will
be
important
on
the
road
to
a
sustainable
energy
future
in
100
years.

12. Wind
Wind
energy
is
the
use
of
wind
turbines
or
sails
to
produce
mechanical
or
electrical
energy.
This
technology
enables
a
sustainable
primary
energy
source
to
be
better
utilized
by
making
use
of
the
inexhaustible
fuel
of
wind
currents
to
create
electrical
power.
There
are
some
marked
benefits
that
have
made
wind
energy
such
an
important
renewable
energy
resource
over
the
last
decade.
These
include
the
fact
that
wind
energy
is
abundant
clean,
and
renewable.
Since
the
sun
dictates
the
wind,
there
will
never
be
a
lack
of
it
as
long
as
there
is
still
an
Earth.
Wind
power
is
also
widely
distributed
across
the
globe,
allowing
wind
energy
to
be
produced
practically
anywhere
though
some
places
are
much
better
than
others.
Power
from
wind
turbines
scales
with
velocity3,
which
means
that
it
doesn’t
take
a
large
amount
of
wind
to
create
quite
a
lot
of
power.
In
addition
to
this,
new
techniques
like
variable
angle
propellers
maximize
the
wind
power
that
each
turbine
can
take
advantage
of.
Wind
turbines
also
take
up
small
amounts
of
land
and
are
relatively
affordable.
The
breakeven
time
for
turbines
is
usually
around
¾
of
a
year.
Finally,
once
the
infrastructure
is
in
place,
the
power
is
practically
free.
The
major
downside
of
this
technology
is
that
it
relies
on
wind,
which
is
inconsistent,
unsteady,
and
unpredictable.
This
is
a
major
drawback
to
having
wind
turbines
in
a
lot
of
areas
of
the
world
that
don’t
get
fairly
consistent
wind
throughout
the
year.
A
wind
turbine
without
wind
is
practically
a
very
expensive
stick,
so
the
systems
need
to
be
set
up
where
wind
is
guaranteed.
This
means
that
even
in
windy
areas,
wind
power
can
never
be
a
stand-­‐along
solution.
Instead
it
must
be
combined
with
a
base
load
system
so
that
there
isn’t
a
loss
of
power
when
the
wind
isn’t
blowing.
Also,
the
system
relies
on
good
energy
storage
when
the
wind
is
blowing
so
that
the
excess
energy
can
be
amassed.
In
addition
to
its
reliability
on
unreliable
wind
gusts,
windmills
are
also
considered
eyesores
in
usually
picturesque
areas
in
addition
to
the
fact
that
they
cause
noise
pollution.
Beyond
the
aesthetic
problems,
windmills
also
have
wildlife
impacts
by
killing
birds,
and
also
can
negatively
affect
temperatures
and
weather
in
the
surrounding
areas
by
causing
the
air
to
be
turbulent
where
it
might
not
usually
be
turbulent
on
its
own.
Wind
energy
will
be
a
very
important
piece
in
the
sustainable
energy
system
future.
Done
correctly,
wind
energy
can
produce
clean,
abundant,
and
practically
free
energy.
This
is
why
wind
energy
has
been
on
the
rise
and
will
continue
to
rise
in
the
next
100
years.
Even
though
there
are
some
disadvantages
to
the
technology,
the
benefits
far
outweigh
them.
The
only
thing
that
could
slow
down
the
wind
energy
craze
is
if
all
of
the
government
subsidies
are
removed,
and
the
cost
of
the
systems
is
prohibitive.
To
be
as
successful
as
it
can
be,
it
will
still
need
the
use
of
good
energy
storage
devices
and
a
solid
renewable
base
load
so
that
the
wind’s
intermittence
won’t
be
very
much
of
a
problem.

13. Nuclear Fission
Nuclear
fission
is
a
nuclear
reaction
in
which
the
nucleus
of
an
atom
splits
into
smaller
parts.
Nuclear
fission
extends
the
availability
of
existing
finite
energy
resources
namely
uranium.
Uranium
is
not
a
renewable
resource
and
Uranium235
comprises
only
0.7%
of
all
Uranium
on
the
Earth.
Nuclear
fission
has
the
benefit
of
having
an
incredibly
large
power
generation
capacity.
This
technology
is
used
as
a
base
load,
and
can
meet
industrial
and
city
needs
for
electricity.
In
comparison
to
fossil
fuel
burning
plants,
nuclear
plants
produce
less
carbon
dioxide
and
other
greenhouse
gasses.
Surprisingly,
during
normal
operation,
nuclear
plants
have
low
operating
costs
in
comparison
to
the
amount
of
electricity
produced.
The
system
is
currently
being
used
today,
which
makes
it
more
viable
than
some
unproven
technologies
including
fusion.
Finally,
waste
recycling
is
become
on
option
for
the
future.
This
recycling
of
the
waste
also
would
produce
more
energy.
To
begin
with
the
cons
we
must
start
with
the
extremely
high
construction
costs
needed
for
radiation
containment
systems
and
procedures.
These
costs
are
only
worthwhile
since
the
system
can
produce
such
large
amounts
of
energy.
The
only
way
these
plants
do
get
built
is
through
large
government
subsidies
and
loan
guarantees.
There
are
also
long
construction
times
needed
to
create
these
plants
because
they
need
to
be
done
so
well
to
mitigate
failure
possibilities.
There
are
known
risks
of
catastrophic
failures
if
something
were
to
go
wrong
or
if
a
natural
disaster
was
to
hit
i.e.
Japan.
Like
all
large
energy
production
plants,
these
are
targets
of
terrorism.
Large
coordination
with
utilities
in
the
surrounding
areas
must
happen
since
produced
power
is
so
large.
This
also
means
that
there
are
substantial
losses
in
the
transport
of
the
energy.
As
far
as
fuel,
most
of
the
remaining
uranium
in
the
world
lies
under
land
controlled
by
tribes
or
indigenous
peoples
who
don’t
want
their
land
mined.
This
poses
a
problem
for
future
fuel
since
it
is
not
a
renewable
resource.
Waste
is
one
of
the
largest
issues
of
nuclear
fission
currently.
Waste
is
usually
kept
in
metal
barrels
in
water
tanks
to
keep
from
overheating.
The
problem
with
this
is
that
there
is
currently
not
enough
room
for
all
of
the
waste,
and
it
lasts
for
200-­‐500
thousand
years
in
the
state
that
it
exits
the
reaction
at.
Recycling
the
waste
after
reaction
can
stop
this,
but
there
is
not
very
much
of
this
implemented
currently,
and
more
infrastructure
must
be
built
before
this
is
viable.
Nuclear
fission
will
be
a
part
of
the
transition
to
the
sustainable
energy
future,
and
will
most
likely
be
used
as
a
base
load
for
a
long
time
after
other
fossil
fuels
stop
producing
as
long
as
uranium
can
be
secured
and
recycling
of
the
waste
is
done
effectively.
The
power
produced
by
these
plants
is
crucial
to
the
US
currently,
and
that
will
not
change
overnight.
There
will
need
to
be
base
load
no
matter
how
large
the
intermittent
technologies
get
and
how
good
the
battery
storage
becomes.
Some
day
fusion
might
erase
the
need
for
nuclear
fission
plants,
but
until
then,
fission
will
continue
to
be
a
key
player
in
every
aspect
of
the
transition
to
a
sustainable
energy
future
over
the
next
100
years.

14. Nuclear Fusion
Fusion is the generation of incredible amounts of energy by a high-energy reaction where two
lighter atomic nuclei fuse to form a heavier nucleus. When they combine, some of the mass is
converted into energy in accordance with E=mc2
. Nuclear fusion is a technology that enables a
sustainable primary energy source to be better utilized. This is because once it is started, fusion
can happen continuously and uses deuterium and tritium as fuel, which can be distilled out of
seawater.
Nuclear fusion is the Holy Grail of energy conversion. If it were realized in its full capacity,
there would never be a need for energy production again. Just like the sun, we would produce
continuous energy from the fusion reactor’s thermonuclear reaction. This energy could boil
steam and generate electricity using conventional turbines. In addition to the benefit of limitless
energy, it would also be clean, carbon free energy. The fuels for the system, as stated before, are
deuterium and tritium. Deuterium can be distilled from seawater and tritium can be “bred” in the
reactor. This means that the fuel will never run out and is very cheap compared to the return in
energy. In comparison to nuclear fission, fusion is easier to control and stop once it’s reacting
since there are no chain reactions happening. Another benefit it has over nuclear fission is that
there is little nuclear waste that only stays radioactive for about 100 years as compared to the
200-500 thousand years of the fission uranium. Finally, cold fusion is being researched heavily
and is said to be much easier to implement.
The const to the system is that you have to over come the electrical repulsion of two hydrogen
atoms using temperatures of around 1 million degrees Celsius. This is hotter than any material on
Earth could possibly withstand. To overcome this issue, a gravity inertia or magnetism is
required to keep the super-hot plasma from melting everything. Unfortunately, both of these
options are extremely hard to create and control. On top of this, there is little room for error
when testing since something that hot would damage many things if not contained properly.
Also, each test is extremely expensive since you need to expend a large amount of energy to get
the system hot enough for a fusion reaction to occur. The earliest projected commercial facility is
not expected until around 2050. As can be expected, start up costs are extreme and will require
many sources of funding to get enough money for a plant.
The other cons are more on a societal and money-usage standpoint. First, the billions being
poured into this research could be put towards other renewables that are guaranteed to work,
while commercial nuclear fusion is still largely unproven. Also, the issue then comes with the
thought of the drawbacks of success if fusion becomes a reality. Is it a good thing to have an
unlimited power supply? Initially this only looks as though it could be a benefit of the
technology, but it has been shown that the more, cheap energy we have available, the more extra
material we will consume, which will deplete resources, and pollute more of the environment. So
a possible con for the future is the ecological impact a limitless energy supply could provide if it
isn’t well regulated.
I believe that fusion will be the ultimate energy source 100 years from now. All signs point to the
fact that with enough funding being poured into it, there should be a realizable solution within 50
years. There are many obstacles along the way, but there is enough time, money, and brainpower
to overcome them in 50 years. Implementation and copying the systems will take time, but 100
years is a long enough time to get the infrastructure in place. This will solve one of the biggest
issues facing the world right now, and will realize the potential of the sustainable energy future.

15. Again the question arises if we can limit ourselves and not over-indulge on our usage, but
regardless, this technology has a very promising chance of ending our need for fossil fuels
completely.

16. Summary and Conclusions
As
can
be
read
in
the
previous
15
pages
of
information,
there
is
quite
a
diverse
landscape
of
energy
conversion
technologies
being
used
today.
Some
of
these
technologies
are
being
efficiently
used,
some
are
in
need
of
improvements,
and
others
have
not
yet
been
realized.
Regardless,
it
is
clear
that
in
the
next
100
years,
there
will
be
many
necessary
changes
being
made
to
energy
system.
I
believe
that
a
sustainable
energy
system
is
very
likely
within
the
next
100
years.
My
vision
for
the
transition
starts
with
batter
improvement.
Of
all
of
the
energy
storage
devices,
batteries
seem
like
the
most
viable
to
push
forward
the
sustainable
energy
future.
Other
storage
devices
will
be
used
in
addition
to
batteries,
but
batteries
have
the
benefit
of
being
efficient,
quickly
discharged,
easily
integrated
in
the
grid,
and
scalable.
This
versatility
makes
it
critical
for
the
sustainable
energy
future.
Battery
improvements
will
push
forward
many
other
technologies,
especially
the
intermittent
renewables.
PV
solar,
solar
thermal,
and
wind
all
stand
to
gain
from
improvements
to
battery
technology.
These
systems
will
be
integral
in
the
transition
away
from
fossil
fuels
into
sustainable
energy.
In
addition,
they
will
also
be
crucial
in
decentralizing
the
grid
so
that
there
is
less
need
for
base
load
systems
to
be
as
large.
This
will
take
time
and
government
subsidies
to
correctly
implement,
but
eventually,
these
renewable
energy
devices
will
be
widespread.
While
improvement
to
the
renewable
energy
infrastructure
is
happening,
optimization
of
the
use
of
fossil
fuels
will
need
to
happen
as
well.
Technologies
like
MHD
and
thermoelectric
generators
will
be
implemented
in
specialized
areas
along
with
the
implementation
of
highly
efficient
combined
cycle
plants
to
make
sure
that
we
are
getting
the
most
energy
out
of
the
remaining
fossil
fuels.
This
will
allow
more
time
for
renewable
energy
to
take
hold
as
well
as
battery
technology
to
improve.
Base
load
systems
will
still
need
to
be
around
though,
and
correctly
done
fuel
cell
plants
could
turn
fossil
fuel
burning
base
load
plants
into
clean,
renewable
fuel
burning
plants.
This
movement
away
from
fossil
fuels
in
base
load
will
come
when
fossil
fuel
reserves
get
depleted
and
cost
of
the
fuel
become
too
high.
If
it
isn’t
fuel
cells,
then
we
will
lean
more
heavily
on
nuclear
fission
plants
and
plants
that
will
recycle
all
of
the
uranium
waste
coming
out
of
the
nuclear
fission
plants.
All
of
this
work
will
act
as
the
transition
period
before
nuclear
fusion
is
realized.
Once
nuclear
fusion
is
perfected
and
made
viable
for
commercial
applications,
there
will
be
no
need
for
energy
conversion
sources
except
turbines
for
the
steam
that
is
produced
and
batteries
to
store
the
excess
energy.
At
this
point
though,
renewable
technology
like
solar
will
be
so
widespread
that
people
will
opt
to
keep
their
decentralized
grids
running
and
use
fusion
as
a
new
base
load.
This
will
allow
people
to
continue
to
be
self-­‐reliant
energy-­‐
wise
and
pull
from
fusion
when
needed.
100
years
from
now
the
sustainable
energy
system
will
be
realized
and
we
will
be
able
to
share
electricity
with
those
who
have
never
had
it
since
it
will
be
in
such
abundance.
At
the
same
time
though,
there
will
have
to
be
limits
on
consumption
so
that
our
advances
don’t
doom
our
planet.
What
a
bright
future
indeed!
“All
pun
intended”