Electric Energy T&D - Index

Electric Energy T&D - EEMag May June 2008 - Index

The Smart Grid is a Green Grid by promoting
efficient use of electricity and increasing
the role of renewable energy in supplying
consumer demand. As a result, investments
in renewable energy sources have increased
significantly. The US Department of Energy’s
Office of Energy Efficiency & Renewable
Energy reported that global investments
increased by 41% in 007 reaching $117.
billion. Almost half of that amount ($54.5
billion) was invested in wind power and this
growth is likely to continue. Last summer, in
the Renewable energy country attractiveness
index, Ernst & Young predicted that
investments in this sector could top $750
billion within 10 years. The United States
was rated first in terms of attractiveness in all
categories. Wind power has proven attractive
to investors with a record 50 1MW installed
in 007, bringing the nation-wide total to
1 59 MW of installed wind power spread
across 34 states.
At present wind, solar power and biomass
make up only % of the installed generation
capacity in the US, with hydro bringing the
total renewable supply to 13% of overall
capacity. Yet in terms of net consumption,
renewables supply only 9% of the electricity
used by US consumers. Coal power on the
other hand accounts for 3 % of installed
capacity, but supplies 49% of overall US
demand. This apparent disparity underlines
three critical challenges facing the widespread
integration of renewable energy into the grid
of the future, namely reliability, economics
and location.
When the Wind Blows
Of the renewable alternatives in the supply mix,
wind has proven most attractive to investors,
yet there is often a large discrepancy between
nameplate capacity and generation output.
An industry standard suggests an efficiency
value of 30%, indicating that a 1 MW turbine
would likely generate on average 8 MWh
over a one year time period. The simple fact
is that despite the use of wind forecasting
to optimize wind power integration, the wind
itself is variable and as such, presents various
operational challenges .
1. Minimum Load: Times of high wind
production may coincide with minimum
load on the grid, requiring the system
planners to reduce production from
conventional power plants until supply
and demand is restored. In some instances
this may drop the spot price.
. Ramping: Variations in wind can ramp
up and down ±10 percent of capacity
much of the time over the hour. However,
variations are most prominent when output
is between 5% and 75%. The largest
variations are when the wind output is
storm driven, reaching maximum output
and reducing output quickly when the
storm has passed.
Solar power faces similar challenges.
Although the sun will always rise tomorrow,
variations in output due to cloud cover and
the changing seasons promote an efficiency
statistic of approximately 30%. The reliability
of hydro-electric resources has also been
questioned. Although historically reliable,
3 I May-June 2008 Issue
the threats of climate change and potential
shifting hydrological patterns have created
concern among system planners about hydroelectric
resources in the coming years.
The Colour of Energy
Power on Demand could be the slogan of any
system operator. Delivering electricity where
and when it’s needed is the mandate of
Independent System Operators across North
America. But just how much are consumers
willing to pay to clear the air? Nuclear and/or
coal power resources make up the base load
of many existing North American electricity
markets due to economics. Coal is cheap
and reasonably plentiful and can easily be
dispatched as demand increases. Yet coal
power generation is responsible for 59% of the
sulphur dioxide and 19% of the nitrous oxide
emitted annually not to mention the carbon
emissions. In an era increasingly dependent
on electricity for economic sustainability,
what price are consumers ready to pay for
increased environmental sustainability?
While renewable energy has attracted
much investment and federal, state and
provincial governments have provided
incentives to increase the percentage
of renewable energy alternatives in
the supply mix, this cost is ultimately
going to be passed on to the consumer.
How supply and demand will be
balanced with increased prices
for a resource seen as essential poses
a challenge for market planners. Will a
price for carbon offset the apparent price
discrepancy between coal and renewables?
If so, what criteria would be used to assign
a value the carbon commodity? What impacts
will such an action have on the economy and/
or the environment?