Electric Energy T&D - Index

Electric Energy T&D - EEMag March / April 2008 - Index

It’s possible to calculate what this means
in dollar terms by looking at the difference
between the amount of electric energy
generated and the amount actually sold at the
retail level. According to data from the Energy
Information Administration, net generation
in the US came to over 3.9 billion megawatt
hours (MWh) in 005 while retail power sales
during that year were about 3.6 billion MWh.
T&D losses amounted to 39 million MWh,
or 6.1% of net generation. Multiplying that
number by the national average retail price
of electricity for 005, we can estimate those
losses came at a cost to the US economy of
just under $19.5 billion.
Congestion charges represent another
significant cost of inefficiency in the T&D
system. Congestion is the result of a number
of factors, notably a lack of adequate
transmission investment and an increase
in bulk power transactions in competitive
energy markets.
The California Independent System Operator
reported congestion costs of $1.1 billion in
004, $670 million in 005, and $476
million in 006. So, despite the progress
being made, the cost of inefficiency in the
T&D system is still quite significant. However,
a more robust T&D system can provide a
level, congestion-free playing field on which
generators can compete.
EET&D: What is demand-side (i.e., as
opposed to supply-side) energy efficiency, and
how successful have demand-side efficiency
measures been in your experience?
Scheu: The average person would likely
point to energy consumption as the point
where efficiency measures can be applied.
Most of these discussions are on the supplyside,
but there are definitely demand-side
energy efficiency efforts as well.
Most people are probably familiar with the Energy
Star program, or with the increasing popularity
of compact fluorescent light bulbs. But the
single largest consumer of electric power is the
industrial motor, which is used to run everything
from assembly lines to compressors to the fans
that blow air into the combustion chamber of a
coal-fired generator.
EET&D: It’s estimated that fully 65% of
industrial power is used in motors of various
sizes, most of which run at full speed whenever
they are turned on. What can be done to alter
that huge operational inefficiency?
Scheu: The vast majority of industrial
motors are controlled by fixed-speed drives
that cannot alter the speed of the motors
they control. Variable speed drives ramp
the motor’s speed up or down to meet the
requirements at a given moment in time. The
resulting energy savings can be enormous.
VSDs can reduce consumption by as much
as 60%, which in energy-intensive facilities
can equate to millions of dollars a year in
energy costs.
EET&D: What can you tell us about some of
the newer, more advanced technologies and
measures that have the greatest potential
for improving efficiency in the transmission
environment?
Scheu: One efficiency measure aimed primarily
at the utilities is a US Department of Energy
initiative aimed at implementing new efficiency
standards for distribution transformers. There
are over 40 million distribution transformers in
service today in the US and are among the most
ubiquitous and the most standardized pieces of
electrical equipment.
The proposed standards will have a relatively
modest impact on the efficiency of a given
transformer, around four percent over current
models. However, when this incremental
gain is multiplied across the thousands of
units operated by even a small utility, the
result is impressive.
Barnoski: At the transmission level,
there are numerous technologies that are
already being applied to boost efficiency in
transmission, and still more that have yet to
reach full commercial implementation. Some
of these technologies include:
• HvDc: Most of the transmission lines that
make up the North American transmission
grid are high-voltage alternating current
(HVAC) lines. Direct current (DC)
transmission offers great advantages over
AC, however: 5% lower line losses, two
36 I March-April 2008 Issue
to five times the capacity of an AC line at
similar voltage, plus the ability to precisely
control the flow of power. In addition HVDC
underground applications eliminate the
issue that many environmentalists have
with overhead AC lines.
• facTS Devices: FACTS – a family of power
electronics devices known as Flexible AC
Transmission Systems - provides a variety
of benefits for increasing transmission
efficiency. Perhaps the most immediate is
their ability to allow existing AC lines to be
loaded more heavily without increasing the
risk of disturbances on the system. Actual
results vary with the characteristics of
each installation, but industry experience
has shown FACTS devices to enhance
transmission capacity by 0-40%.
• gas-Insulated Substations (gIS): Gasinsulated
substations essentially take all of
the equipment you would find in an outdoor
substation and encapsulate it inside of a
metal housing. The air inside is replaced
with a special inert gas, which allows all of
the components to be placed much closer
together without the risk of a flashover.
The result is that it is now possible to
locate a substation in the basement of a
building or other confined space so that
the efficiency of high-voltage transmission
can be exploited to the fullest extent.
EET&D: The Business Roundtable’s Energy
Task Force T&D Working Group, chaired by
ABB, recently published a list of energyefficient
actions and technologies. Can you
share what some of those technologies are?
Scheu: This working group recently
published a summary of efficiency-enhancing
actions and technologies. Technology options
for improving effects of T&D may be classified
into three categories:
1. Technologies for expanding transmission
capacity to enable optimal deployment
and use of generation resources
. Technologies for optimizing transmission
and distribution system design and
operations to reduce overall energy losses
3. New industry standards for energy
efficiency power apparatus.