6. Active Solar Power
Energy from sun is
stored in a “thermal
mass”
When needed, heat
from thermal mass is
then pumped
throughout structure
7. Active Solar Power
This also refers to
electrical generation
using solar power
Two ways to do this are
photovoltaic cells and
huge commercial
electric facilities
This shows the diagram
for the house seen in the
previous slide. The PV
panels are on the roof
9. Large-scale Solar Electric Site
These facilities use solar power to heat
water to form steam. The steam goes to
generate electricity just as in fossil fuel or
nuclear electric plants.
No release of air pollutants
No electricity generated at night
They do work on cloudy days, though.
10. Passive Solar Power
Works on the
principle that hot air
rises and cool air
sinks (convection)
Solar heats air and it
moves through
convection through
the structure or to
thermal mass
12. Solar Power
Benefits
– Abundant
– No greenhouse gases,
few other pollutants
– Simple, minimal
repair needed
– Cheap over the long
term
Detriments
– Retrofitting needed if
structure is not already
designed as passive solar
– Has limitations, night,
some locations better
such as south rather than
north facing slopes
– Initial capital outlay can
be high
14. Wind Power
• Wind power is the conversion of wind
of wind energy into a useful form of energy.
• Most modern electrical wind power is
generated by converting the rotation of turbine
blades into electrical currents by means of
an electrical generator.
• Wind power is also used to propel ships
using sails.
• Windmills provide mechanical power, and
were originally developed for milling
grain for food production.
15. Wind power
Can be used for mechanical tasks, e.g.
pumping water
Areas where winds are
stronger and more
constant, such as
offshore and high
altitude sites, are preferred
locations for wind farms.
16. Electrical Power Windmills
High speed, low
torque machines
Will turn themselves
off if wind speed
exceeds their limits.
Used for generation of
electricity for direct
use or storage in
batteries
17. Effects of windpower
No greenhouse gases
Few other pollutants
Cheap
Abundant
Simple
Some noise pollution
Metal blades interfere
with TV & radio
reception
Aesthetic pollution
No evidence for bird
death, but can kill bats
Positive Negative
18. Where is wind power available?
Wind power not highly
suited to these areas
22. • The power of flowing water has been used for
hundreds of years to operate machinery. This power
can also be used to generate electricity.
• Large scale hydroelectric schemes involve building
a dam across the end of a river valley to create a
reservoir.
• This is done high up in a mountainous area.
• Once they are built, hydroelectric schemes provide
a cheap and reliable source of electricity.
Hydro Power
23. Negative effects of Hydropower
Flooding the land
Displacement of local inhabitants
Local climatic changes
Tectonic activities (Earthquakes)
Loss of species (aquatic & terrestrial)
Loss of normal nutrient flow down river
Changes temperature of water, too
24. Positive Effects of Hydropower
Can generate electricity
Can do mechanical work, e.g. grind grain
No greenhouse gases
Initial construction provides jobs
26. What Is Biomass Energy
• Biomass energy is the use of living and recently
dead biological material as an energy source.
• Ultimately dependent on the capture of solar energy
and conversion to a chemical (carbohydrate) fuel.
• Theoretically it is a carbon neutral and renewable
source of energy.
27. How It Works
• Traditional: forest management, using wood as
fuel
• Use of biodegradable waste
Examples: manure, crop residue, sewage, municipal solid
waste
• Recent interest in agricultural production of
energy crops
Should be high yield and low maintenance
Examples: corn, sugarcane, switchgrass, hemp, willow,
palm oil, rapeseed, and many others
Does not have to be a food crop
Recent interest in bioengineered (GM) plants as fuel
sources
Production of a liquid or gaseous biofuel
Biogas due to the breakdown of biomass in the absence of O2
29. Biomass Energy
Disadvantages
• Low energy density/yield
In some cases (eg, corn-derived
bioethanol) may yield no net energy
• Land conversion
Biodiversity loss
Possible decrease in agricultural food
productivity
• Usual problems associated with
intensive agriculture
Nutrient pollution
Soil depletion
Soil erosion
Other water pollution problems
30. Biomass Pros & Cons
Burning biomass gets
rid of solid waste
Creates energy
Creates new markets
for crops
Burning biomass
releases CO2 and
other gases associated
with combustion
Creates solid waste
from ash
May cause more
grasslands to be
planted to corn
33. How It Works
– Geothermal power plants
• Use earth’s heat to power steam turbines
– Geothermal direct use
• Use hot springs (etc) as heat source
– Geothermal heat pumps
34. Advantages
• Renewable
• Easy to exploit in some cases
• CO2 production less than
with fossil fuels
• High net energy yield
36. Conclusions
Major difficulties in attaining target of
10% of electricity generated by
renewables by 2010
Main contributors to this target will be :-
1)Offshore and Onshore
windfarms/clusters
2)Biomass/wood, straw, etc
3)Photovoltaic
But policies like Climate Change Levy
and the Renewables Obligation will help
establish renewables.
