Renewable & Clean Energy

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Energy and Power

Keywords: definition, energy, types, useage

What is energy? Why is it such a useful concept? How does it relate to power?

Energy is the capacity to do work (both are measured in Joules). Power is the rate at which energy is transformed from one state to another, often from a stored state into work (a Joule of energy transformed per second is a Watt of power). Subsistence living requires about 200 W per person. Western living requires about 10 kW per person. Humankind currently uses about 12.5 TW of power, most from fossil fuels. Ten billion people living a western lifestyle (the not-impossible goal of many futurists) would require 100 TW of power.

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5 years 36 weeks ago

Radioactive Milk

Keywords: activity, dose, nucleosynthesis, Radioactivity

Milk contains enough radioactive potassium-40 to set a Geiger Counter humming. But it didn't come from Fukushima, or any human activity.

Milk (and own bones) contains a lot of ancient radioactive potassium-40, which was made in a supernova explosion about five billion years ago.

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6 years 3 weeks ago

Why can't you just turn a nuclear reactor off?

Keywords: nuclear reactor, shutdown

When a nuclear reactor gets into trouble, what's wrong with hitting the off switch?

When a uranium nucleus fissions into two, the resulting nuclei are not stable; they continue to decay and generate heat long after the fission chain reaction has stopped.

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6 years 4 weeks ago

What is a millisievert?

Keywords: dose, human health, ionizing radiation

One Sievert means exposure to enough high-energy electromagnetic radiation to deposit one joule of energy in one kilogram of living tissue. A millisievert is 1/1000 of a sievert. But how dangerous is it?

The measure of ionizing radiation dose, as is applicable to human health, is the Sievert (Sv). One Sv implies a health impact equivalent to one joule of X-rays being absorbed by each kg of living tissue. Activity, the mean number of decay events per second, is measured in Becquerels (Bq). Knowledge of the activity, mean energy release per event, and exposure time, allows to estimate the dose.

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6 years 5 weeks ago

Heating Efficiency

Keywords: efficiency, electric, energy, gas, power

Which is better: gas or electric heat?

Calculating or measuring efficiency means tracking the power all the way from source to end-user.

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6 years 31 weeks ago

Comparing Energy and Heat Units

Keywords: BTU, cost, energy, greenhouse gases, oil barrel, quad, R-value, thermal conductivity, thermal resistance, unit conversion, Watts

How do I compare heat and energy values given in different units?

A look at how to compare the costs of natural gas, gasoline and electricity and how to convert between various heat units including R-values, U-values, BTU/h, W and more.

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6 years 42 weeks ago

Clean Coal

Keywords: energy, Fossil fuel, greenhouse gases, power

An oxymoron?

Calculating how much coal we have to burn in a typical large power station to produce 1 GWe for a year.

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6 years 46 weeks ago

Solar Energy in a Temperate Climate.

Keywords: photovoltaic cell, solar cells, solar energy, solar radiation

Does it pay to cover your roof with solar panels in Vancouver?

We show the example calculation of expected amount of energy, which can be obtained in Vancouver from a roof covered with solar cells.

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6 years 46 weeks ago

Hydro-Electric Dam Demo

Keywords: dams, hydro-electricity, power

Energy from Water?

An estimate of the power output from a model hydro-electric dam.

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6 years 46 weeks ago

Nuclear Energy Basics

Keywords: energy, health, ionizing radiation, nuclear, power, safety

What is the physical basis of nuclear power? Is nuclear power good or bad for the environment, safe or dangerous for us?

A look at the energy in the nucleus of a uranium atom, how this can be used to provide a reliable source of energy, and impact of this on the environment.

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6 years 47 weeks ago
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