Lecture 15: Wind and Solar Flashcards
Why move to renewable energies?
- nonrenewable are finite and emit pollutants (health and climate risks)
What are the conventional renewables?
- renewables that are established
- hydro and biomass
Why are “new” renewables referred to as “new” ?
- they are not used on a wide scale yet
- they are still developing
- they will contribute greatly to meeting future energy needs
- they will contribute to a nation’s energy independence
How much of Canada’s energy comes from renewable forms
- over half of the renewable energy comes from hydropower, then biomass, then wind
is the EROEI higher or lower for renewable energies? Why?
- much higher EROEI: technology is efficient and cost effective
- but renewables must double
why does solar energy have so much potential?
- the energy of the sun daily is more than 1000 times the energy we use
- a single rooftop PV system could meet all energy needs
How has PV changed in price? Why is this useful?
- 2010-2021 prices fell 89%: may become cheaper than coal!
How much of power is supplied by solar in the US? Canada? Why might PV be more attractive to developing nations?
- 10% of power provided by the US
- Canada is less
- attractive in developing nations who do not have power grids and power lines already installed
What can solar energy be used for?
- everything: heating, electricity, plant growth, etc.
What is passive solar energy?
- the most common way to collect solar energy
- harnessing energy without the use of electrical/mechanical devices
-eg; house windows designed to warm in winter and cool in summer
What is active solar energy?
- uses tech. to focus, move, store solar energy
- uses electrical/mechanical devices to heat water/buildings, generate electricity
What are some technologies used to harness solar energy?
- reflectors focus sun
- or use PVs to directly generate electricity
- flat plate solar collectors
- solar hot water
- Solar wall
- PV technology
- concentrated solar power: similar to power plant, all energy directed to collect steam
How efficient are solar panels? How long do they last?
- most efficient is 46%, but most commercial are 15-20% efficient
- last ~25 years
What are some disadvantages of solar panels?
- requires minerals, space constraints, intermittent, electronic waste, energy storage, expensive start ups
What can wind energy be used for?
- electricity: minimal in Canada but on the rise
What is the source of wind?
- energy that drives wind comes from the sun
- energy form sun hits earth at uneven distributions causing areas of high pressure and low pressure
- air masses move from areas of high to low : forms kinetic energy
- kinetic –> mechanical –> electrical
Describe the structure of a wind turbine?
- scalloped, like a whale fin, to be more aerodynamic
What factors need to be known to calculate the energy from a wind turbine?
- density of air, wind speed, rotor area turbine design
- wind speed increases energy cubed (ie: double windspeed = 8 times more energy)
Describe the efficiency of the turbine
- a turbine can never convert all of the wind’s power: betz law says maximum 59.3% efficient,
- may be closer to 40%
- BUT it’s more efficient than solar!!
What are the benefits and challenges of offshore wind?
- offshore has higher wind speeds but costs more
- what are disadvantages of wind farms?
- space, intermittent, NIMBY, threatens wildlife, noise pollution/health impacts
What is an economy of scale?
- the more we make the cheaper it will become: research/development/efficiency contributes to a country’s energy independence
