Direct forms of solar energy
1
direct forms of solar energy solar
annual Sun’s radiation solar
Source: https://doi.org/10.1016/j.rser.2016.05.022
annual Sun’s radiation solar
June December
Source: PVGIS © European Communities, 2001-2008
Portugal: 7 - 7.6 kWh/m2 Portugal: 1.6 - 2.2 kWh/m2
2 times central Europe+30% central Europe
summerwinter
S
v v
S
N W
E
↵S
'S'S
↵S
N W
E
Sun’s path solar
mid latitude at North hemisphere
altitude azimuth
solar technologies solar
low temperature solar collectors
concentration solar power
solar photovoltaic
Low temperature solar collectors
6
Low temperature solar collectors solar
glazed flat plane collector solar
Pumped solar system solar
thermosiphon solar system solar
evacuated solar tubes solar
world thermal power capacity solar
world thermal power capacity solar
47
02
Source: See Endnote 7 for this section.
Source: See Endnote 7 for this section.
Source: See Endnote 9 for this section.
China 68%
Germany 4.6%Turkey 4.6%Brazil 1.7%India 1.5%Japan 1.5%Israel 1.3%Austria 1.3%Greece 1.3%Italy 0.9%Australia 0.8%Spain 0.8%
Rest of World 11.3%
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
250
200
150
100
50
0
Gigawatts-thermal
79
195223
68
255
171148
124
595144
91105
Note: Data are for glazed water collectors only. preliminary
Turkey 2.6%Germany 1.8%India 1.5%Brazil 0.7%Italy 0.6%Israel 0.5%Australia 0.4%Spain 0.4%Poland 0.4%France (mainland) 0.3%Austria 0.3%
Rest of World 7.9%
China 83%
TOTAL ADDED ~ 49 GWth
FIGURE 15. SOLAR WATER HEATING GLOBAL CAPACITY ADDITIONS, SHARES OF TOP 12 COUNTRIES, 2011
SOLAR THERMAL HEATING
FIGURE 16. SOLAR WATER HEATING GLOBAL CAPACITY, SHARES OF TOP 12 COUNTRIES, 2011
TOTAL CAPACITY ~ 223 GWth
FIGURE 17. SOLAR WATER HEATING GLOBAL CAPACITY, 2000–2012
Area: 70 x 106 m2
Ti
Tf
m
Flate plate collector solar
mass [kg]
fluid thermal capacity [J/(kgK)]
output temperature [K]
input temperature [K]
[J] Q = mc(Tf � Ti)Q = mc(Tf � Ti) [W]
m
c
m mass flow [kg/s]
Tf
Ti
heating energy/power solar
⌧↵
⇢
⇢
thermal lossesG
collector efficiency solar
thermal losses
thermal losses
optical losses
constituents, such as Fe2O3. Figure 4.81 gives an example of the wavelengthdependence of the transmittance, τλ, through ordinary window glass, definedas the fraction of incident light that is neither reflected [cf. (3.12)] norabsorbed,
τλ = 1− ρλ − αλ: (4.111)
For a collector of the type considered, multiple reflections may take placebetween the absorber and the cover system as well as within the cover sys-tem layers, if there is more than one. The reflections are mostly specular(angle of exit equal to angle of incidence) at glass surfaces, but mostly dif-fuse (hemispherically isotropic) at the absorber surface. Thus, the amount ofradiation absorbed by the absorber plate, in general, cannot be calculatedfrom knowledge of the total incoming flux but must be calculated for each
1
0.5
Abs
orpt
ance
al=
e l
00.5 1 2
Wavelength (10−6m)
5 10
FIGURE 4.80 Spectral absorptance (or emittance) of a commercial “black chrome” type ofselective surface. (Based on Masterson and Seraphin, 1975.)
0.50
0.5
Tran
smitt
ance
tl
1
1Wavelength (10−6m)
2 5 10
FIGURE 4.81 Spectral transmittance, (1 ρλ αλ), of 2.8 × 10−3 m thick glass layer with a Fe2O3
content of 0.1. (Based on Dietz, 1954.)
4.4 Solar Radiation Conversion 455
espectral absorptivity of selective surfaces solar
decreasethermal losses
decreaseoptical losses
constituents, such as Fe2O3. Figure 4.81 gives an example of the wavelengthdependence of the transmittance, τλ, through ordinary window glass, definedas the fraction of incident light that is neither reflected [cf. (3.12)] norabsorbed,
τλ = 1− ρλ − αλ: (4.111)
For a collector of the type considered, multiple reflections may take placebetween the absorber and the cover system as well as within the cover sys-tem layers, if there is more than one. The reflections are mostly specular(angle of exit equal to angle of incidence) at glass surfaces, but mostly dif-fuse (hemispherically isotropic) at the absorber surface. Thus, the amount ofradiation absorbed by the absorber plate, in general, cannot be calculatedfrom knowledge of the total incoming flux but must be calculated for each
1
0.5
Abs
orpt
ance
al=
e l
00.5 1 2
Wavelength (10−6m)
5 10
FIGURE 4.80 Spectral absorptance (or emittance) of a commercial “black chrome” type ofselective surface. (Based on Masterson and Seraphin, 1975.)
0.50
0.5
Tran
smitt
ance
tl
1
1Wavelength (10−6m)
2 5 10
FIGURE 4.81 Spectral transmittance, (1 ρλ αλ), of 2.8 × 10−3 m thick glass layer with a Fe2O3
content of 0.1. (Based on Dietz, 1954.)
4.4 Solar Radiation Conversion 455
espectral transmissivity of the glazing surface solar
opaque tolongwaveradiation
transparent toshortwaveradiation
GAcQu
optical losses thermal losses⇢GAc + (Tabs � Tamb)UAt
Qu = GAc � ⇢GAc � (Tabs � Tamb)UAt
collector useful energy solar
available solar energy
usefulenergy
losses
⌘ = ⌘0 �↵1�T
G
⌘0
�T
G=
⌘0↵1
�T
G
⌘ ⌘ = (1� ⇢)� UAt
Ac
�T
G Tabs ' Tf
Tamb ' Ti
�T = Tf � Ti
dU
dT= 0
Assumptions
collector efficiency solar
�T
G
⌘
Optical efficiency
Saturation temperature efficiency
collector efficiency solar
�T
G
⌘
optical losses100%
thermal losses
collector efficiency solar
solar collector efficiency solar
water-to-external air temperature difference
effici
ency
⌘ = ⌘0 � ↵1�T/G� ↵2�T 2/G
(G=800 W/m2)
Ti
Tf
Qu
useful energy
solar collector efficiency solar
• solar collector efficiency • pipes thermal losses • storage tank thermal losses
QuQ
sol
system efficiency solar
Qi
Qf
Qaux
Qu
= Qf
�Qi
�Qaux
Qsol
⌘ =Q
u
Qsol
system efficiency solar
Qi
Qf
Qaux
Qsol
FS =Qu
Qn
Energy needsQn = Qf �Qi
solar fraction solar
low water temperature for swimming pools (no storage tank needed) evaporator component of heat pump
unglazed solar collectors solar
installed solar collectors by type solar
55
02
Notes: Costs are indicative economic costs, levelised, and exclusive of subsidies or policy incentives. Several components determine the levelised costs of energy (LCOE), including: resource quality, equipment cost and performance, balance of system/project costs (including labour), operations and maintenance costs, fuel costs (biomass), the cost of capital, and productive lifetime of the project. The costs of renewables are site specific, as many of these components can vary according to location. Costs for solar electricity vary greatly depending on the level of available solar resources. It is important to note that the rapid growth in installed capacity of some renewable technologies and their associated cost reductions mean that data can become outdated quickly; solar PV costs, in particular, are changing rapidly. Costs of off-grid hybrid power systems that employ renewables depend largely on system size, location, and associated items such as diesel backup and battery storage. Data for rural energy are unchanged from GSR 2011, with the exception of wind turbines. i Litre of diesel or gasoline equivalent Source: See Endnote 99 in Wind Power section for sources and assumptions.
TABLE 2. STATUS OF RENEWABLE ENERGY TECHNOLOGIES: CHARACTERISTICS AND COSTS (CONTINUED)
Technology Typical Characteristics Capital Costs Typical Energy Costs (USD/kW) (LCOE – U.S. cents/kWh)
Transport Fuels Feedstocks Feedstock characteristics Production costs (U.S. cents/litre)i
BiodieselSoy, rapeseed, mustard seed, palm, jatropha, waste vegetable oils, and animal fats
Range of feedstocks with different crop yields per hectare; hence, production costs vary widely among countries. Co-products include high-protein meal.
Soybean oil: 45-90 (Argentina/USA) Palm oil: 30–100 (Indonesia/Malaysia/Thailand/Peru)Rapeseed oil: 120–140 (EU)
EthanolSugar cane, sugar beets, corn, cassava, sorghum, wheat (and cellulose in the future)
Range of feedstocks with wide yield and cost variations. Co-products include animal feed, heat and power from bagasse residues. Advanced biofuels are not yet fully commercial and have higher costs.
Sugar cane: 45–80 (Brazil)Corn (dry mill): 60–120 (USA)
Biogas digester Digester size: 6–8 m3 n/a
Biomass gasifier Size: 20–5,000 kW LCOE: 8–12
Solar home system System size: 20–100 W LCOE: 40–60
Household wind turbine Turbine size: 0.1–3 kWCapital cost: 10,000/kW (1 kW turbine); 5,000/kW (5 kW); 2,500/kW (250 kW) LCOE: 15–35+
Village-scale mini-grid System size: 10–1,000 kW LCOE: 25–100
Technologies Typical characteristics Installed costs (USD/kW) or LCOE for Rural Energy (U.S. cents/kWh)
Hot Water/Heating/Cooling (continued)
Solar thermal: Domestic hot water systems
Collector type: flat-plate, evacuated tube (thermosiphon and pumped systems)Plant size: 2.1–4.2 kWth (single family); 35 kWth (multi-family)Efficiency: 100%
Single-family: 1,100–2,140 (OECD, new build); 1,300–2,200 (OECD, retrofit) 150–635 (China) Multi-family: 950–1,850 (OECD, new build); 1,140–2,050 (OECD, retrofit)
1.5–28 (China)
Solar thermal: Domestic heat and hot water systems (combi)
Collector type: same as water onlyPlant size: 7–10 kWth (single-family); 70–130 kWth (multi-family); 70–3,500 kWth (district heating); >3,500 kWth (district heat with seasonal storage)Efficiency: 100%
Single-family: same as water onlyMulti-family: same as water onlyDistrict heat (Europe): 460–780; with storage: 470–1,060
5–50 (domestic hot water) District heat: 4 and up (Denmark)
Solar thermal: Industrial process heat
Collector type: flat-plate, evacuated tube, parabolic trough, linear FresnelPlant size: 100 kWth–20 MWthTemperature range: 50–400° C
470–1,000 (without storage) 4–16
Solar thermal: CoolingCapacity: 10.5–500 kWth (absorption chillers); 8–370 kWth (adsorption chillers)Efficiency: 50–70%
1,600–5,850 n/a
costs solar
OUTROS SISTEMAS SOLARES
DESTILADOR SOLAR
PAREDES DE ACUMULAÇÃO
FORNO SOLAR
BIBLIOGRAFIA
Ehrlich, R. Renewable Energy, a first course Solar Thermal (10.1 a 10.5, 10.8, 10.11)
Boyle, G. Renewable Energy, Power for Sustainable Future Solar Thermal Energy (2.6, 2.10)