Introduction to Energy Concepts

EnergyDerived from Green en (in) and ergon

(work) – “in work” “Forceful or vigorous language”

First definition - Aristotle “Capacity to do Work”

Modern accepted definition

“Energy is Eternal Delight” William Blake, 1757-1827

Four Basic Forms of Energy Kinetic = 0.5 x mass x speed2

Thermal – energy of vibrating molecules within a material

Electrical – force between electrical charges

Chemical – electrical energy that holds molecules together

Gravitational – also known as “potential energy” – force x distance = weight x height = m x g x h

Nuclear – forces that hold atoms together

Units of EnergyEnergy requires a force. Each form of energy

has it’s own force: gravity, strong & weak nuclear forces, electrical, and kinetic forces.

Kinetic Force = Mass x Acceleration Unit of force = 1 Newton = 1 Kilogram x 1 m/s

Energy is a measurement of work accomplished by a force

Energy = Force x Distance 1 Joule = 1 Newton x 1 Meter

Energy and PowerEnergy is a quantity, like distance.

1 kilowatt-hour = 1000 Watts x 1 hour 1 kilowatt-hour = 3.6 x 106 Joules

Power is a rate, like speed, it is the rate that energy is converted from one form to another. 1 Watt = 1 Joule / Second

Laws of Thermodynamics First Law: In any transformation of energy

from one form to another, the total quantity of energy remains unchanged. “Energy is neither created nor destroyed, it only changes forms.”

Second Law: In all energy changes, the potential energy of the final state will be less than that of the initial state – (useful energy is always lost.) “Lost” energy is usually energy that has been

converted to heat, but it could be noise (kinetic energy of air), or other forms of wasted energy.

EfficiencyThe ratio of the amount of useable

energy obtained to the amount of energy input is the efficiency of a process. This is usually expressed as a percent and

it is always less than 100%.

Energy definitionsPrimary Energy – amount of energy

contained in the initial source of energyDelivered Energy – amount of useable

energy delivered to the customerUseful Energy – amount of energy

attributed to the amount of work accomplished

Where do we get energy from and what do we use it for?

Renewable vs Non-Renewable Solar Wind Biomass Hydro Ocean

Coal Oil Gas Nuclear

Fuel is not getting any cheaper..

1000 years of CO2 Concentration

1000 Years of Temperature Changes

Edgartown, MA - today

Edgartown with 1 m sea level rise

Edgartown with 1 m sea level rise and storm surge from Cat. 2 hurricane

Every Year an Average Coal Plant Releases 3,700,000 tons of CO2 10,000 tons of SO2. 500 tons of particulates 10,200 tons NOx 720 tons of CO 220 tons of volatile organic

compounds (VOC) 170 pounds of mercury 225 pounds of arsenic 114 pounds of lead

And there are over 600 of them in the US.Source: Union of Concerned Scientists: www.ucsusa.org

Types of Pollutants CO2 – Global Warming

CO – Health problem PM –Respiratory and

heart disease, haze SOx – Acid Rain,

respiratory illness, haze NOx – Ozone

formation, acid rain, smog, nutrient loading, global warming

Mercury – Neurotoxin Lead – Neurotoxin Arsenic - Poison VOCs – Numerous

health problems Ozone – Health

problems, damage to flora & fauna

Hundreds of other toxic chemicals