284
in the process. Can require a large amount of water for cooling, unless “dry cooling”
systems are installed—and these cost more money. Thermoelectric solar power
uses the sun’s radiation and heating energy to make steam or otherwise turn a
turbine- linked generator. It can require some water for washing solar panels and
for steam cycles. Wind power uses a simple air turbine to turn a generator when the
wind blows, and uses no water. Tidal power uses tidal ocean flows to turn a turbinelinked generator. Photovoltaic solar power uses the sun’s radiation to directly create a voltage using silicon chips. This is the only production source that is often
distributed in small units on rooftops; other production mechanisms are usually
implemented at the much larger “utility scale.”
Electricity is transported by the Power Grid. High-voltage AC lines are used to
transport electrical power from large power plants to cities. Sometimes these lines
are hundreds of miles long, and incur significant voltage losses in transmission.
High-voltage transmission lines are vulnerable to damage by storms and fires.
Because these lines are expensive and difficult to site, power production facilities
are usually built along existing transmission lines. Power Grids are among humanity’s most complex machines, and they involve countless power plants, transmission
systems, transformers, substations, distribution systems, and organizations. A power
grid can be any size, but they tend to be regional in scope and tend to loosely obey
national boundaries. It is economical to transport electrical power within a power
grid, and harder to transport it between power grids. Failures can cascade across a
Power Grid’s transmission lines but stop at a grid’s boundaries; historical cascading
failures in the USA have tended to affect one or two balancing regions within a grid,
but not the whole grid. The USA and Canada share two grids, the Western
Interconnection and the Eastern Interconnection. The Western Interconnection also
serves a small part of northwestern Mexico. Texas maintains its own power grid that
stops at the state’s borders but can selectively interconnect using transformers.
Electricity is distributed using substations and mid-voltage distribution circuits that
are normally less than a mile long.
Electrical energy has historically been very difficult and expensive to store,
which requires producers to be extremely agile and “ramp” their production rates
rapidly to match supply with demand at every moment. Failures to match supply
with demand during peak demand periods is a common cause of failure in these
systems, because when insufficient or excessive voltage is available at any point in
the system, breakers trip to shut off power and protect the power grid from damaging itself. “Baseload” power plants using coal and nuclear technologies are difficult to ramp, and are normally operated at a constant rate. But demand for power
goes up and down by a factor of 2–3 in most cities, peaking seasonally in the summer and daily in the late afternoon and early evening, so the gap between the peaks
and valleys of demand must be filled with a combination of storage, demand
response, and ramping power production. Grid-scale battery technologies and thermal storage technologies are beginning to become cost-effective. Electric cars are
increasingly storing power in their batteries. An excellent technology both for storage and for ramping production is the “pump and store” hydroelectric facility that
pumps water uphill to store energy and/or releases water and high-demand times to
B. L. Ruddell et al.
in the process. Can require a large amount of water for cooling, unless “dry cooling”
systems are installed—and these cost more money. Thermoelectric solar power
uses the sun’s radiation and heating energy to make steam or otherwise turn a
turbine- linked generator. It can require some water for washing solar panels and
for steam cycles. Wind power uses a simple air turbine to turn a generator when the
wind blows, and uses no water. Tidal power uses tidal ocean flows to turn a turbinelinked generator. Photovoltaic solar power uses the sun’s radiation to directly create a voltage using silicon chips. This is the only production source that is often
distributed in small units on rooftops; other production mechanisms are usually
implemented at the much larger “utility scale.”
Electricity is transported by the Power Grid. High-voltage AC lines are used to
transport electrical power from large power plants to cities. Sometimes these lines
are hundreds of miles long, and incur significant voltage losses in transmission.
High-voltage transmission lines are vulnerable to damage by storms and fires.
Because these lines are expensive and difficult to site, power production facilities
are usually built along existing transmission lines. Power Grids are among humanity’s most complex machines, and they involve countless power plants, transmission
systems, transformers, substations, distribution systems, and organizations. A power
grid can be any size, but they tend to be regional in scope and tend to loosely obey
national boundaries. It is economical to transport electrical power within a power
grid, and harder to transport it between power grids. Failures can cascade across a
Power Grid’s transmission lines but stop at a grid’s boundaries; historical cascading
failures in the USA have tended to affect one or two balancing regions within a grid,
but not the whole grid. The USA and Canada share two grids, the Western
Interconnection and the Eastern Interconnection. The Western Interconnection also
serves a small part of northwestern Mexico. Texas maintains its own power grid that
stops at the state’s borders but can selectively interconnect using transformers.
Electricity is distributed using substations and mid-voltage distribution circuits that
are normally less than a mile long.
Electrical energy has historically been very difficult and expensive to store,
which requires producers to be extremely agile and “ramp” their production rates
rapidly to match supply with demand at every moment. Failures to match supply
with demand during peak demand periods is a common cause of failure in these
systems, because when insufficient or excessive voltage is available at any point in
the system, breakers trip to shut off power and protect the power grid from damaging itself. “Baseload” power plants using coal and nuclear technologies are difficult to ramp, and are normally operated at a constant rate. But demand for power
goes up and down by a factor of 2–3 in most cities, peaking seasonally in the summer and daily in the late afternoon and early evening, so the gap between the peaks
and valleys of demand must be filled with a combination of storage, demand
response, and ramping power production. Grid-scale battery technologies and thermal storage technologies are beginning to become cost-effective. Electric cars are
increasingly storing power in their batteries. An excellent technology both for storage and for ramping production is the “pump and store” hydroelectric facility that
pumps water uphill to store energy and/or releases water and high-demand times to
B. L. Ruddell et al.