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UAU212F Spring 2012
Throstur Thorsteinsson ([email protected]) 1
Sustainable Energy Options
UAU212F
SOLAR ENERGY
Throstur Thorsteinsson [email protected]
2012 NASA's Solar Dynamics Observatory snapped this view of the powerful X1.7-class solar flare that erupted at 1:37 p.m. EST on Jan. 27, 2012.
http://www.space.com/14388-massive-flare-tops-sun-active-week.html - video
Solar energy - overview
⇨ Solar energy is intercepted by the Earth is
about 10,000 times greater than the rate at
which humankind consumes energy
⇨ The world installed capacity of solar thermal systems
at the end of 2009 has been estimated to be 180 GWth.
⇨ As of the end of 2009, the installed capacity for PV
power production was about 22 GW
Solar power potential - technical
For the minimum estimates, minimum annual clear-sky irradiance, sky clearance and available land used for installation of solar collectors are assumed
For the maximum estimates, maximum annual clear-sky irradiance and sky clearance are adopted with an assumption of maximum available land used.
Solar power potential Solar power
⇨ Use of Solar energy to heat houses, water or to
produce electricity - issues: ⇨ Solar energy is subject to daily and seasonal variations –
which necessitates a backup system driven by other fuels.
⇨ Is subject to geographical variation – the availability of
solar energy depends on latitude. Areas near the equator
get more solar energy than e.g. Canada.
⇨ Weather conditions: cannot collect solar energy if it is
cloudy, and the solar irradiance is diffuse requiring
significant land space.
⇨ Siting option: available land for large scale use of solar
power is limited by the current use of land – e.g. urban
areas, agricultural areas etc.
UAU212F Spring 2012
Throstur Thorsteinsson ([email protected]) 2
Sunlight Sun angle
Average annual
Annual average insolation
TOA
Ground
Average insolation Average
insolation
http://solargis.info/
UAU212F Spring 2012
Throstur Thorsteinsson ([email protected]) 3
Issues
Expensive
Need backup system
Land intensive
No carbon dioxide
emissions/nor other
air pollution
Local (domestic)
resources used …
Can be of small
scale - decentralized
Can connect to grid
Perpetual
Social
⇨ Solar technologies offer opportunities for positive social
impacts, and their environmental burden is small. ⇨ Solar technologies have low lifecycle greenhouse gas.
⇨ Potential areas of concern include recycling and use of toxic materials in
manufacturing for PV, water usage for CSP, and energy payback and land
requirements for both.
⇨ An important social benefit of solar technologies is their potential to improve
the health and livelihood opportunities for many of the world’s poorest
populations addressing some of the gap in availability of modern energy
services for the roughly 1.4 billion people who do not have access to electricity
and the 2.7 billion people who rely on traditional biomass for home cooking
and heating needs.
⇨ On the downside, some solar projects have faced public concerns regarding
land requirements for centralized CSP and PV plants, perceptions regarding
visual impacts, and for CSP, cooling water requirements. ⇨ Land use impacts can be minimized by selecting areas with low population density
and low environmental sensitivity.
⇨ Similarly, water usage for CSP could be significantly reduced by using dry cooling
approaches.
⇨ Studies to date suggest that none of these issues presents a barrier against the
widespread use of solar technologies.
Environment
⇨ Utility-scale solar energy environmental considerations
include ⇨ land disturbance/land use impacts;
⇨ potential impacts to specially designated areas;
⇨ impacts to soil, water and air resources;
⇨ impacts to vegetation, wildlife, wildlife habitat, and sensitive species;
⇨ visual, cultural, paleontological, socioeconomic, and environmental justice
impacts, and
⇨ potential impacts from hazardous materials.
Solar systems
⇨ Low temperature solar systems ⇨ Passive - no mechanical moving parts
⇨ Active – mechanical moving parts
⇨ High temperature solar systems e.g. ⇨ Solar tower
⇨ Parabolic trough, Parabolic dish
⇨ PV-cells
Passive Solar Heating
⇨ Passive solar heating is a technique for
maintaining comfortable conditions in
buildings by exploiting the solar irradiance
incident on the buildings through the use of
glazing (windows, sun spaces, conservatories)
and other transparent materials and managing
heat gain and loss in the structure without the
dominant use of pumps or fans.
Generation of Electricity
⇨ Solar thermal energy is used in a
concentrating solar power (CSP) plant to
produce high-temperature heat, which is then
converted to electricity via a heat engine and
generator
⇨ Solar energy is converted directly into
electricity in a device called a photovoltaic
(PV) cell
UAU212F Spring 2012
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Low T systems
⇨ Passive ⇨ Architectural designs. Capture solar energy and use to
heat or cool houses e.g. ⇨ Sunrooms
⇨ Solar cookers
⇨ Block high angle sunlight, but allow winter sunlight
through
⇨ Active ⇨ Solar domestic hot water heater system
⇨ Solar space heating- either water or air
Passive systems
⇨ Captures sunlight within
a structure and converts
to heat ⇨ Efficient windows
⇨ Thermal mass to absorb heat
(capacity to store heat)
⇨ Direct or indirect gain
Solar collector
Unglazed Solar Collectors are primarily used to pre-heat make-up ventilation air in commercial, industrial and institutional buildings with a high ventilation load.
Active system
⇨ Solar domestic hot water
heater system:
⇨ Consists of three
components: i. solar collector panel
ii. storage tank
iii. circulator system to transfer
the heat from the tank to the
use area.
⇨ Pump driven by electrical
power - thus active
High T power system
⇨ All rely on four basic elements: 1. collector/concentrator – captures and concentrates the
solar energy which is then transported to a....
2. receiver, absorbs the sunlight transferring the heat
energy to a working fluid e.g. steam
3. transport/storage passes the fluid from the receiver to
the power generation system. – and may be stored for
later use.
4. power conversion from AC to DC electricity.
Types
A) Parabolic trough: Solar farm. Consists of long
parallel rows of identical concentrator modules
concentrates solar radiation.
B) Central receiver/power tower: Huge arrays of
computer controlled mirrors called heliostats track
the sun and focus sunlight onto a fixed receiver
which is located on the top of a tower.
C) Parabolic dishes: Parabolic shaped focus
concentrator in the form of a dish that reflects solar
radiation onto a receiver mounted at the focal point.
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Examples CSP
CSP solar tower Parabolic solar concentrator
Solar Thermal Plants
Solar collectors capture and concentrate sunlight to heat a synthetic oil called therminol, which then heats water to create steam. The steam is piped to an onsite turbine-generator to produce electricity, which is then transmitted over power lines. On cloudy days, the plant has a supplementary natural gas boiler.
PV Cells
⇨ Direct conversion of sunlight into electricity
⇨ Sunlight falls on the solar cell –which is
either a transparent wafer thinner than a sheet
of paper or just thin film made of
semiconducting materials
⇨ When hit by sunlight, creates electricity
⇨ The simplest photovoltaic cells power watches
and calculators and the like, while more
complex systems can light houses and provide
power to the electrical grid.
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Throstur Thorsteinsson ([email protected]) 6
Advantages / Dis
Reliable
Quiet – no moving parts
Wafers composed of
silicon
Flexible.
No direct carbon
dioxide emissions
Land disturbance low if
this system is e.g.
placed on a roof.
Need large collection areas,
diffuse
Need storage systems
Geographically and
temporally variable
Need back-up systems
Cost is high – both in
operating cost and in the
investment cost.
Availability of the materials
in the cells (is a
nonrenewable resource).
PV solar cell
Photovoltaics is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.
http://science.nasa.gov/science-news/science-at-nasa/2002/solarcells/
PV
As light hits the solar panels, the solar radiation is converted into direct current electricity (DC). The direct current flows from the panels and is converted into alternating current (AC) used by local electric utilities. Finally, the electricity travels through transformers, and the voltage is boosted for delivery onto the transmission lines so local electric utilities can distribute the electricity to homes and businesses.
PV installed global
http://energyforumonline.com/657/world-installed-photovoltaic-capacity-2000-2009/ 20
11 in
stal
lati
on
s
27.7 GW
Solar cell efficiency spectrolab.com/
wiki/Organic_solar_cell
Cost ⇨ Over the last 30 years, solar technologies have seen very
substantial cost reductions.
⇨ The current levelized costs of energy (electricity and heat)
from solar technologies vary widely depending on the upfront
technology cost, available solar irradiation as well as the
applied discount rates. ⇨ The levelized costs for solar thermal energy at a 7% discount rate range
between less than USD2005 10 and slightly more than USD2005 20/GJ for
solar hot water generation with a high degree of utilization in China to more
than USD2005 130/GJ for space heating applications in OECD countries with
relative low irradiation levels of 800 kWh/m2/yr.
⇨ Electricity generation costs for utility-scale PV in regions of high solar
irradiance in Europe and the USA are in the range of approximately 15 to 40
US cents2005 /kWh at a 7% discount rate.
⇨ Current cost data are limited for CSP and are highly dependent on other system
factors such as storage. In 2009, the levelized costs of energy for large solar
troughs with six hours of thermal storage ranged from below 20 to
approximately 30 US cents2005 /kWh. Technological improvements and cost
reductions are expected
UAU212F Spring 2012
Throstur Thorsteinsson ([email protected]) 7
Cost of PV Photovoltaic costs (1985 Yen per Watt installed) as a function of cumulative installed capacity (in MW), Japan 1976–1995. Data source: [Watanabe, 1995] and Watanabe, 1997.
Energy Economics Volume 20, Issues 5–6, 1 December 1998, Pages 495–512
Cost
http://blog.cleanenergy.org/files/2009/04/lazard2009_levelizedcostofenergy.pdf
Lifecycle GHG Emissions of PV