Environmental Engineering Reference
In-Depth Information
Transmission of electricity allows the pooling of different renewable energy
sources, even on a transcontinental level, and can link areas with large renewable
energy resources to regions with high electricity demand. While conventional al-
ternating current transmission technology is not suited to transmitting electricity
across distances of more than 500 km, High Voltage Direct Current (HVDC) tech-
nology can be used to link, for example, the vast solar resources in the world's Sun
Belt to demand centers, thus facilitating the provision of dispatchable solar bulk
electricity.
A number of companies are seriously considering covering large areas of the
Sahara Desert with photoelectric cells and transmitting the electricity via HVDC
thousands of kilometers to Europe. Transference of electricity over such large dis-
tances is not unusual.
One of the advantages of HVDC is the low cost for transmission of very high
power over very long distances, in the range of 0.5-1.5 Єct/kWh. Losses incurred
in transmitting power over a distance of 1,000 km total around 3%. Today's HVDC
schemes have a maximum power of 3,000 MW and transmission distances of
around 1,000 km. A new type of converter, called HVDC Light, was introduced in
the late 1990s. Unlike AC cables, there is no physical restriction limiting the dis-
tance or power level for HVDC cables underground or under water. There is an
emerging market for this new technology in transferring power under the sea, for
example, from wind parks, to strengthen the electricity grid in areas where there
are no overhead lines.
Smart grids consist of an intelligent monitoring system that keeps track of all elec-
tricity flowing in a system. They are capable of integrating intermittent renewable
sources, such as solar and wind, and turning on home appliances, such as washing
machines or other electric equipment.
The power grids of the 20th century were only capable of sending electricity
from a few power stations to a large number of users. It was a unidirectional sys-
tem. Smart grids are bidirectional and can accept and reroute electricity to and from
many decentralized sources, including homes that have solar panels on their roofs.
During the day, when the sun is shining, the homes can send energy to the grid and
