- Controllerstarts the wind turbine at speeds of 8 to 16 mph and stops the turbine at about
65 mph to prevent damage to the blades and components. An anemometer measures the
wind speed and transmits the data to the controller. - A brakestops the rotor in emergencies or high wind speeds. The brake is applied mechani-
cally, electrically, or hydraulically.
Ethanol and Biodiesel
Ethanol is an alcohol based fuel that is made from the sugars found in corn and barley.
Other sources such as rice, sugar cane, and potato skins are also used to produce ethanol.
Most of the ethanol used in the U.S. today is distilled from corn. You have seen E10 signs
at gas stations. This E10 designation refers to a fuel that is a mixture of 10% ethanol and
90% gasoline. Another renewable fuel that you may have heard about is Biodiesel. Biodiesel
is a fuel that is commonly made from vegetable oils or recycled restaurant grease, and can
be in diesel engines. The B20 designation refers to a blend of 20% biodiesel with 80%
petroleum diesel.
As we mentioned at the beginning of this section, as future engineers you are faced with
two problems, energy sources and emissions. The solutions to these problems require innova-
tive approaches, so, study hard as you take your engineering classes, prepare well, and along the
way think about ways that you might be able to solve these problems.408 Chapter 13 Energy and Power
Ming Dong
My name is Ming Dong. I am currently a
sophomore at Carnegie Mellon University.
I am double majoring in mechanical engi-
neering and biomedical engineering. I
came to the Unites States when I was 12,
and I have grown up in a traditional Chi-
nese family. My parents were hoping that I would major
in chemistry or biology. They felt that engineering is
too “boyish.” But I decided to major in engineering
because for me it is the combination of math, science,
and art — three of my favorite subjects.
Now I like engineering even more, it is an exciting
field. I learn something new every day. Engineering is
creativity, it is the combination of math and science,and how to apply them to real life. It is about creating
something that’s real and helps solve real problems. The
biggest challenge I faced was being comfortable in class
with males. There are about 15% of girls in mechanical
engineering class. It was hard at first, because I have to
prove that “I am not just a girl. I am as good as your
guys.” But once I got used to having classes with boys,
it seemed less obvious to me the difference between girls
and guys; we are all engineering students.
After graduation, I am hoping to find a job and
work for a couple of years, and then return to graduate
school to enter the joint PhD/ MD program, and con-
duct research that directs me toward neuroengineering.Student Profile
Source:Courtesy of Ming Dong
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