cive230 lec13 - fossil fuels

sustainable energy components

safe, affordable, abundant, minimum negative impacts, available to all

energy poverty

an economic condition under which families are unable to access or afford commercially provided energy. The families rely on gathered biomass or on limited purchases of kerosene, charcoal and batteries

energy security

the ability of a nation to protect itself from the economic, political, and social disruptions of an interrupted supply of a critical energy resource

is this US energy secure?

historically no, their oil consumption is far greater than their domestic oil production therefore putting themselves at risk of interrupted supply of a critical energy source due to dependence on foreign countries. however in the past decade, their production of oil has increased significantly, significantly reducing their reliance on imported oil. with an increase in domestic renewable energy sources, the US could become energy independent in the near future.

what does solar heating do

drives convection currents that can be harvested as wind energy – or as wave energy in the oceans

convection

a movement within a fluid or gas due to temperature variation - by the external heat, fluids become less dense and rise, and colder, denser fluids sink under the influence of gravity

energy cycle

the path from extraction to consumption (considers the total path of energy from its extraction in raw form to its processing and distribution and finally to its point of consumption) - extraction, distribution to processing, converting to consumption form, distribution to consumers, infrastructure for consumption

net energy

the amount of usable energy at the final step, less the energy used in production and transport

energy density

amount of energy (MJ) produced per unit mass of fuel (MJ/kg) - amount of energy available from unit of an energy source

energy ladder

developed by the International Energy Agency (IEA), describes how both the quality and quantity of energy used in a household changes as income rises

four sectors of of energy end-users

transportation (human and freight), industrial (manufacturing, mining, construction, agriculture), electric power generation (coal and fuel oil power plants), commercial and residential (Business, government, nonprofit enterprises, houses)

finite energy sources

those that took million of years to form and can only be generated on a geological timescale, if at all (ex. fossil fuels, uranium)

renewable energy sources

those that are replenishable within a human lifetime (ex. biomass)

infinitely renewable energy sources

those that derive from planetary processes,

and are never ending in their supply (ex. wind, solar)

examples of energy sources

oil (and derived products: gasoline, diesel, heating oil, etc.), coal, natural gas, biomass, thermal, geothermal, hydro, solar, photovoltaic, nuclear, wind

energy reserve

represents the availability of resources that are recoverable (extractable and usable) using existing technology and the recovery is economically profitable

reserve-to-production ratio

the time (years) it would take to deplete current proved reserves based on the current consumption/production

Canada’s main source of energy production

hydro

fossil fuel advantages

• High energy content

• Available infrastructure to support processing / consumption

fossil fuel disadvantages

• Finite supply (not infinite)

• Environmental Impacts – GHG, particulates, damage to environment during extraction

• Political insecurity – supply is limited by “ownership” or lands from which supply is derived

renewable energy advantages

• Unlimited supply

• Fewer environmental impacts

• Better distributed globally

renewable energy disadvantages

• Lower/variable energy content

• Lack of supporting infrastructure and higher start-up costs

peak oil

for any geographical area, production rate for a finite resource (e.g., oil) tends to follow bell-shaped curve - Oil production increases as exploration uncovers new sources and improved technology extracts more oil. Oil production then declines, as oil is a finite resource – less new reserves are uncovered, and old fields are exhausted

has Canada reached peak oil

Canadian oil production (via standard deep drilling) peaked in the mid-1970s, but due to the new offshore basins being exploited in Atlantic Canada and the boom of the Alberta Oil Sands overall production will not peak until the late 2020s

influences on peak oil

global demand, energy transitions, and climate policies

canadian energy security (oil)

very energy secure, domestic oil consumption is much lower than domestic oil production

mathematical model of sustainable energy

𝑅(𝑡)= 𝑅₀ − 𝐺𝐸(𝑡) + 𝑌(𝑡) or 𝑅(𝑡) = 𝑅₀ − 𝐺𝐷(𝑡)/η + 𝑌(𝑡)

where 𝑅₀ represents the reserves of a fuel source at the beginning of the year, GE(t) represents the global extraction rate, Y(t) represents additional reserves of that fuel source found during the year, GD(t) represents demand for energy, and η represents the efficiency coefficient, converting total energy production to demand

negative environmental impacts of coal

• the most co2 of any energy source

• acid rain

• mercury

• arsenic

• heavy metal contaminated ash and sludge

Reductions in coal consumption - Canada

24% since 1990 and 41% since 2000

Natural gas negative environmental impacts

• slightly lower carbon emissions than other fossil fuels

• shale gas has higher carbon emissions than conventional gas

• fracking fluids (organic chemicals, etc.) can leak into water sources and cause water contamination

total efficiency of electricity generation

product of efficiencies of three energy changes: combustion energy to steam energy in boiler, transfer of energy stored in steam to mechanical energy within a turbine, transfer of turbine mechanical energy to electricity

total efficiency of contemporary fossil fuel power plants (FFPP)

32-35%

Brayton cycle

uses natural gas as the combustion material and uses air in place of water to store and transfer energy to the turbine

Combines cycle

The combined cycle combines the Rankine and Brayton cycles by using the waste heat of one cycle as input heat of the other. The Brayton cycle is a gas turbine that produces a high-temperature exhaust, which is then used to heat water for the Rankine steam turbine.

Combined heating and power/cogeneration

CHP simultaneously generates electricity and heat from a single fuel source by using the heat lost from electricity generation to provide heat for buildings or drive cooling systems.

enthalpy

energy stored in the steam

specific enthalpy

amount of steam energy per unit mass