Environmental Engineering Reference
In-Depth Information
TABLE 3.3
Albedo of Some Surface Types
Surface
Albedo (% Reflected)
Water (low sun)
10-100
Water (high sun)
3-10
Grass
16-26
Glacier ice
20-40
Deciduous forest
15-20
Coniferous forest
5-15
Old snow
40-70
Fresh snow
75-95
Sea ice
30-40
Blacktopped tarmac
5-10
Desert
25-30
Crops
15-25
of forage base could result in reduced grazing, which would disrupt the longstand-
ing economic and cultural characteristics of ranching operations. Potential direct
impacts include conversion of land to provide support services and housing for
people who move to the region to support the solar development, with associated
increases in roads, traffic, and penetration into previously remote areas. The addi-
tional transmission infrastructure associated with solar development could create
various impacts as well.
These are merely examples of the types of impacts that may be associated with
solar development. For an exhaustive discussion, see USDOE (2010c) and other
detailed environmental-impact studies. Less well-studied impacts are also important
and must be evaluated as solar development progresses. For example, the local and
global climate effects of changes in albedo due to widespread PV and CSP deploy-
ment are not well studied.
Albedo
is the ratio between the light reflected from a sur-
face and the total light falling on it. Albedo is a surface phenomenon—basically a
radiation reflector. Albedo always has a value less than or equal to 1. An object with
a high albedo, near 1, is very bright, while a body with a low albedo, near 0, is dark.
For example, freshly fallen snow typically has an albedo that is between 75% and
90%; that is, 75% to 95% of the solar radiation that is incident on snow is reflected.
At the other extreme, the albedo of a rough, dark surface, such as a green forest, may
be as low as 5%. The albedo values of some common surfaces are listed in Table 3.3.
The portion of insolation not reflected is absorbed by the Earth's surface, warming it.
This means that Earth's albedo plays an important role in the Earth's radiation bal-
ance and influences the mean annual temperature and the climate on both local and
global scales. One study evaluated the net balance between the greenhouse gas emis-
sions reduction resulting from PV replacing fossil-fuel-based power generation (with
PV growing to meet 50% of world energy demand in 2100) and a decrease in desert
albedo due to PV module covering, concluding that the PV albedo effect would have
little impact on global warming (Nemet, 2009).
