Page 27 - Fundamentals of Ocean Renewable Energy Generating Electricity From The Sea

18 Fundamentals of Ocean Renewable Energy

1.3.3 Interconnectors and Grid Storage
In many regions, electricity grids do not function in isolation. For example,
there is an integrated North American grid, which links the United States and
Canada, and the UK grid has interconnectors that can import/export electricity
from/to France, Ireland, and the Netherlands. The French interconnector can
import up to 2 GW from France (e.g. during summer months when France
has a surplus of nuclear power), and export electricity during winter months.
This interconnectedness can help alleviate some issues associated with the
intermittency of renewable generation. For example, Germany currently has
7
around 45 GW of wind and 40 GW of solar capacity, and is on track to
increase its installed capacity to 59 GW (wind) and 62 GW (solar) by 2030
[12]. Germany’s electricity grid is very much interconnected with the neigh-
bouring grids of France, the Czech Republic, Norway, Austria, Switzerland,
and the Netherlands. Wind and solar power installations are, by their nature,
intermittent. Therefore, during hours of darkness or during times of low wind
speed, it will be necessary for Germany to import electricity under a scenario of
a high penetration of renewables. Increased interconnectedness could be one
way of coping with a high penetration of renewables. For example, over a
continent such as Europe, there will be significant geographical and temporal
(phase) differences in the wind resource. A large interconnected grid could help
smooth out such differences in generation, capitalizing on spatial differences in
the resource. Note that tidal energy, which has the major advantage of being
predictable, is a strong candidate for such geographical phasing of renewable
energy [13,14].
Another way to reduce intermittency in electricity generation is through
storage. At present, there is 193 GW of grid storage installed throughout the
world, with around half of this capacity fairly equally shared by China, the
United States, and Japan (Fig. 1.13). Within each of these countries, pumped
hydro accounts for the greatest contribution to grid storage (China: 99.6%,
United States: 90.4%, Japan: 99.1%), but the United States has a more diverse
blend of storage than either China or Japan, including substantial levels of
electrochemical (4.2%) and thermal (2.7%) storage. Clearly, increased grid
storage capacity would be consistent with a high penetration of renewables,
and would also provide a means of backup power, even in the context of
conventional (thermal) power generation.

1.3.4 Levelized Cost of Energy
A key factor that influences the development of (or the investment in) a
renewable energy technology is its cost compared with other, conventional,
power plants. Many policy discussions over the costs of different technologies
for electricity generation are based on the concept of levelized costs. Levelized

7. See https://www.carbonbrief.org/how-germany-generates-its-electricity.