Chapter 15!Non renewable Energy

Net Energy

• 1st law of thermodynamics: it takes high quality energy to get high quality energy e.g. Before oil becomes useful it has to go thru several steps, each of which uses energy

• 2nd law of thermodynamics: some of the high quality energy used in each step is automatically wasted.

• Some is unnecessarily wasted

• Net energy = useful energy available - energy needed to make it available

• E.g. it takes 9 energy units to make 10 units = net energy ratio of 10/9 or 1.1

• Conventional oil has had a high net energy ratio because it's been found in large deposits. As those are depleted, net energy ratio decreases

54 of the 64 major oil fields are in decline

Energy resources with low or negative energy yields are subsidized in order to compete in the

marketplace • e.g. nuclear power

• Low net energy ratio -

• lots of energy to extract, transport and convert uranium

• build and operate nuclear power plant

• store radioactive materials

• dismantle plant

Reducing energy waste increases net yields !

84% of commercial energy in US is wasted !

41% is automatically wasted !

43% is unnecessarily wasted

we know how to fix it and cut energy waste

Oil

• OIL:!

• 1/3 of world's commercial energy is from oil

• 40% is used by US

• Grow food, transport people, transport goods, make plastics, make asphalt, paint, medicines, cleaning fluid, pesticides, synthetic fibers

• - a.k.a. Petroleum, crude oil, sweet crude, light crude

• Black, gooey liquid

• Hundreds of hydrocarbons

• Trace amounts of S, O, N , impurities

Conventional oil

Unconventional Oil• Molasses

• Some is left behind in wells

• Some is extracted from oil shale rock and tar sand

• Lots of energy to extract which decreases its net energy yield

• 70%of world's supply

Oil Refining

How long will supplies last?• Demand has been increasing since 1950

• Prices will rise

• US is largest consumer

• China expected to surpass

• Conventional oil - 2050-2100

Oil reserves• Potential - not necessarily proven; may be difficult, i.e. Costly to

extract!

• Possible sources - global consumption grows 2% each year

• Saudi Arabia - 7 year supply

• Alaska's North Slope - 6 mos (US <3y)

• Alaska Arctic National Wildlife Refuge - 1-5 months (US 7-24 mos)

• BP Deepwater Horizon - amt. was only enough for 5 days for US

Options?

• Find more

• Use less

• Waste less

• Alternative energy sources Toronto Canada

Advantages to using conventional oil

• Ample supply for decades

• High net energy yield

• Low land disruption

• Efficient distribution system

Disadvantages to using conventional oil

• Water pollution

• Environmental costs not reflected in price

• Releases CO2 when burned

• Vulnerable to international supply interruptions

Unconventional Oil: Tar Sands

• Mixture of clay, sand, water, bitumen

• Bitumen- thick, sticky, high sulfur

• Alberta, Canada has 75% = state of NC

• Major harmful impacts to land, air, water, climate to produce oil from this region

Problems with tar sands• Some is close enough to surface to strip mine

• Cut forest, drain wetlands, divert rivers

• Huge air pollution

• More earth is being removed in Canada's Athabasca Valley than anywhere on earth

• Requires large amt water

• Lots of waste water and toxic sludge ponds

Shale Oil• Source of heavy oil locked up in rock and ore

• Lots of energy to extract and convert to shale oil so low energy yield

• Fracking and horizontal drilling

• Requires lots of water

• lg amts in CO, WY, UT (dry)

• Potentially 4x Saudi Arabia

• 11x Alberta's tar sands

Natural Gas• Mixture of gases

• 50-90% methane

• Propane, butane

• H2S which is highly toxic

• High energy yield

• Lies above crude oil reservoirs

• When nat gas field is tapped, propane and butane are liquified (LPG) under high pressure for transport

• Methane is purified and pumped into pipelines

• It can be liquified too (LNG)

• By 2025 US largest importer of LNG

Coal• Ancient swamps

• 42% of world energy

• US has most

• Coal reserves should last 250 y

• Dirtiest fossil fuels

• Land degradation

• Air pollution

• Water pollution

• Trace amts of radioactive materials

• Toxic ash

Coal ash• Arsenic, cadmium, chromium, lead, mercury, radium (heavy metals)

• Can be used in concrete and drywall

• Fertilizer

• Most is buried or in holding ponds. Potential groundwater contamination

• EPA (2007) toxic metals and other harmful substances in coal ash ponds have contaminated groundwater in 63 communities

• Little or no regulations

• Knoxville, TN

• 2008 spill 1 billion gallons

• Pond rupture

• 300 football fields of toxic sludge

• $1.2 billion to clean up

Nuclear Power: !clean but expensive!

Nuclear Power• Uses nuclear fission to generate heat to

boil water, produce steam to turn turbines, to run generator to make electricity

• Fission: splitting of an atomic nucleus into two smaller parts

• Small amount of mass releases a HUGE amounts of energy

• Chain reaction

• 20% of electricity

• U-235

• Takes place in a reactor

• Most are light water reactors LWRs which are highly inefficient. Lose lots of heat to environment

• Energy also used to mine, upgrade and transport uranium, deal with waste

• Total net energy loss is 92%

Each pellet contains energy = a ton of coal

• Control rods are moved in and out of the reactor to absorb heat and regulate the rate of fission

• Water is used to remove the heat to prevent a meltdown which would release radioactive materials into the environment

• All of this is stored within a containment shell of thick concrete to contain radioactive materials in case of a meltdown or partial meltdown

Storing nuclear waste• Radioactive waste must be

stored

• Most stored on site

• Yucca Mountain

• Need to be stored safely for 10,000 y

• Vulnerable to terrorists

Chernobyl

• Worst nuclear disaster in history until Fukushima

• 1986

• 2 explosions in reactor

• Meltdown, fire that burned for 10 days

• Radioactive cloud over huge area and eventually spread worldwide

• Cancers, death, immune system problems, birth defects

Fukushima

• Earthquake 9.0 caused tsunami 3/11/11

• Knocked out power to cooling pumps resulting in meltdown in three reactors

• Leaking radiation into ocean which is expected to reach US 4/2014

• Cesium plume

• Fisheries still closed off Fukushima because of cesium

• Under reported then and now

Nuclear Fusion: the power of the future

• Two nuclei of a light element such as H are forced together at an extremely high temps until they fuse

• No meltdown risk

• No large release of radioactive materials

• Not feasible yet...no research has been able to create more energy than what is used