Renewable energy

Define clean energy

Keeps the air clean- no carbon or ghg emissions

Define Green energy

Energy derived from natural sources

Define renewable energy

Energy from sources that are renewable/recyclable

What are some renewable soures?

• solar

• wind

• hydropower

• biomass

• geothermal

Is renewable energy always carbon free and vice versa?

No, most is generally interchangable but some are specific

Nuclear is not renewable, but is carbon free

Biofuels are renewable, but no carbon free

Why are windfarms on land and not all offshore?

Offshore is beneficial because of constant wind and lack of visual disturbance

However, many coasts have very agressive conditions where hurricanes would destroy turbines- also expensive to get energy back to land sometimes

How do turbines generate energy?

Conversion of kinetic energy in wind to mechanical power, which is then converted into high voltage electrical power

List issues with wind farms

• visual and auditory disturbance

  • hard to sell people on it

• expensive installation

• wind doesn’t always blow

• hard to wire generated power from rural/marine location to city that could use it

• impacts to local wildlife (birds, bats)

What are the issues with solar?

• weather dependent

• storage batteries expensive

• requires a lot of space (that can’t really be used simultaneously)

• Hazardous components (cadmium film on cells, telluride, sometimes lead)

• transport, manufacturing, and installation still creates emissions

Are solar panels toxic?

No, not terribly

very dependent on how the waste is manage but toxic elements are in solid form (minimal leaching), life span is long (>20 years) so less wasteful than phones

How efficient is hydro compared to fossil fuel?

Way more efficient, 90% compared to 60% of coal and fossil fuel

What are the two types of hydro plants?

• Dam- creates reservoir that allows regulation of power generation

• Run of the river- pulls some water from typical stream course through turbine

What are the pros and cons of run of the river hydro plants?

Pros- less environmentally damaging as it uses existing current for power, and doesn’t impact current stream course

Cons- less controllable amount of power generation, limited storage capacity, subject to seasonal flow changes

Which provinces are the most dependent on hydro?

Newfoundland - 97% of power generated

Saskatchewan- 96%

Quebec- 94%

BC- 90%

16 million people (40%) live in places where 90% or more of power comes from hydro

What are some issues with hydropower?

• issues for downstream communities

  • scarcity of water

  • impact water quality

  • alter habitat

• Can alter habitat above dam too (flooding of areas for reservoir)

• safety concerns and maintenance issues

• droughts or floods

What’s the difference between geothermal power plants and geothermal heat pumps?

Power plants use heat for earths core to generate steam (to turn a turbine and generate power) while heat pumps funnel the heat directly from the ground into buildings to be heated

What are some uses of geothermal heat?

• hot water for bathing/swimming

• space/district heating

• greenhouse heating

• aquaculture

What are some issues with geothermal heating?

• Some locations may cool over time

• production is limited to areas near tectonic boundaries (high seismic activity)

• drilling and exploration is expensive

• release potentially harmful gases (ex. hydrogen sulphide coming out of yellowstone)

• can sometimes be in nationally protected areas, so hard to work around those rules

What are some pros of using biomass power?

• Rich in hydrogen- good for fuel

• can be dried and stored for long periods of time

• more sustainable than fossil fuels as the carbon emitted is not from long term storage

• organic, so naturally and quickly regenerated

• widely available

• low transport costs (exists everywhere)

What are some sources of biomass?

• wood

  • forestry plantations

  • natural forests and woodlands

  • forestry residuals

• Agriculture residuals

  • straw

  • stover

  • cane

  • green wastes

• Agro industry wastes (rice husk, etc.)

• animal waste

• industrial waste (such as stuff from paper manufacturing

• sewage

• municipal solid waste

• food processing waste

What are some issues with biomass?

• costly to start

• large ghg emissions still

• odours

• concerns about pathogens from municipal waste

• destruction if habitats to fuel biomass (mass deforestation, etc.)

• low efficiency

• requires a lot of space

What are some pros of hydrogen power?

• versatile

• carbon free at point of use (creates water)

• produced from a variety of inputs

• transported long distance easily

• highest energy per mass

What is hydrogen power ?

it is the burning of hydrogen gas to produce energy

How can hydrogen be produced?

Amassed in water, hydrocarbons, and biomass - not a lot in atmosphere so one of those needs to be processed to produce it

Can be done using:

• thermochemical processes - energy from fossil fuel used to split h from h20

• biological process- microbes used to produce h2 as a byproduct of metabolizing biomass

• H20 splitting- electrolysis of water using high temps of solar collection (becoming more cost effective)

Define what a control rod is

A metal that is used to slow down the reaction by absorbing excess neutrons (typically cadmium or silver)

Define what a moderator is

A substance used to slow down neutrons bombarding the uranium (usually water, as its also a heat sink, but sometimes graphite)

Define what a containment structure is

The main plant

A building that houses the reactor core, reactor vessel, and steam generator (usually made of super thick concrete)

How do nuclear plants make power?

Works the same way that all energy generation does- capture energy by turning a turbine (steam in this case but also water, wind, etc)

When did nuclear start being used for electricity generation?

1950s

What are some cons of nuclear power?

• high cost to start up

• takes decades to build before becoming operational

• nuclear waste

What are the two types of nuclear plants?

Standard Pressurized Water Reactor (PWR) and Breeder reactor (CANDU)

How does the Candu reactor differ from the PWR?

Candu reactor uses heavy water as a moderator (opposed to regular water) and natural uranium (rather than enriched)

What is the advantage of a CANDU reactor?

Heavy water (2H2O) doesn’t absorb any neutrons so the system is more efficient

Can be refueled while operating at full power, doesn’t require a complete shutoff like most

Safer- not pressurized, natural uranium (safer for humans working there)

What are the two isotopes that are used for nuclear energy?

Uranium- 235 and Plutonium- 239

Uranium is more typical for power generation, plutonium is associated with weapons use

What are the mining methods for uranium?

• open pit

• underground

• in-situ leaching

• heap leaching

What are some issues with uranium mining?

• often stored in water to prevent oxidation, which then must be treated as nuclear waste

• contamination prevention is usually dependent on geological features

What are the main components of radioactive waste?

• spent fuel rods

• used ppe

• old equipment

• contaminated soil and water (potential leaking hazard)

What are the three categories of nuclear waste?

1. low level- requires less than 300 years to lose radiation

2. intermediate level- requires greater than 300 years to lose radiation

3. high level- spent nuclear fuel, so much energy left, uncalculatable amount of time left

How is low level waste disposed?

Usually stored on site, sometimes in a shielded area, until safe to handle or dispose of normally

How is high level radioactive waste stored?

Two step process

1. wet- held in water storage tanks for 7-10 years, cool water circulated to cool it down until cool enough to be moved (by robots)

   1. Dry- long term (up to thousands of years), usually in canisters of steel, concrete or a combination (issue- most dry storage contains have a lifepsan of 50 ish years

What is one proposed solution to this, and why are small towns interested in it?

Bury the waste!

Would need to be in a place that has metamorphic or sedimentary rock, low tectonic activity, easy access, and not far from where the nuclear waste is created

Towns want this as this storage would require secondary monitoring to ensure power, water supply stay connected- high qualification, high paying jobs, with an almost indefinite need (permanent good jobs)