>>In this video we will talk about energy.
What are our sources of energy? Well one of
our major sources are fossil fuels, which
come from the earth. What are these fuels?
Well, coal, which forms from plant material.
It's a major producer of electricity in the
United States. About 20 percent of our electricity
comes from coal. We have lots of reserves
of coal, but there are issues with coal. It
can be dirty, and burning of coal can produce
acid rain and releases CO2 into the atmosphere.
Peat can be another energy source. Peat changes
into coal when you bury it, but in some countries
they actually burn peat, as for example in
Scotland. Another major fossil fuel would
be hydrocarbons, like gas and oil. It forms
from organic-rich sediment or from source
rocks, like we saw the Woodford Shale on our
field trip to the Arbuckle Mountains. What
happens is the oil and gas is formed in these
source rocks and then it migrates into reservoir
rocks. But we now know that some source rocks
are also reservoirs, like the Barnett Shale
in Texas and the Woodford Shale in Oklahoma.
This is fairly new development. It's in the
last 15 years, and it has dramatically increased
our reserves of natural gas. Related to these
shale gas reservoirs is horizontal drilling
and hydrofracturing. 20 years ago if you wanted
to drill a well, you would drill a vertical
well, and you would intersect, let's say,
a 100 meter unit of rock that you could extract
hydrocarbons from. But now what happens is
we can drill horizontally. You drill down,
and then you drill laterally. So you can drill
through a reservoir unit for miles, so you
can encounter a lot more of the rock and therefore
extract a lot more hydrocarbons. The oil companies
use hydrofracturing to break the rocks up,
and that allows more gas and oil to be extracted.
This has been a major change in the oil business
because unproductive units, which didn't have
a lot of porosity and permeability and couldn't
produce much oil and gas, now we can get oil
and gas out of them because of horizontal
drilling and hydrofracturing. Another type
of fossil fuel would be oil shales and oil
sand. For example, there are major deposits
of oil sands in Canada.
So what are some of the negatives with extracting
fossil fuels? We mentioned a few for coal
already, but for hydrocarbons you have oil
spills, which can be a major problem. Another
issue is injection of wastewater, which can
produce earthquakes. And then there's CO2
release, which can influence global warming.
What about other energy sources, like renewable
energy sources? Perhaps many of you have noticed
there are many, many new wind farms all over
the Midwest. Those produce a lot of energy.
Another source is geothermal energy. That's
hot rock underground can heat rocks up, and
you can put water down there, and you can
produce energy from that. Hydroelectric power
provides 15 percent of the electricity in
the United States today on major rivers like
the Colorado. Tides can be another source
of energy. We currently don't have any plants
in the United States that use tides, but there
are some around the world. Solar energy is
gaining popularity, particularly as the costs
for solar energy have come down. It will probably
not be a major factor, however, for many decades.
And we have fission and perhaps fusion power
plants. Our current nuclear power plants are
fission power plants, and perhaps we will
have fusion power plants in the future.
