Letter to the Editor: An explanation of energy conservation

DEAR News of the Area,

YOUR correspondent Wayne Duesbury asks for an explanation on how “renewable energy systems do not contribute to climate change”.

As a retired teacher of physics and astronomy (including planetary atmospheres), allow me to acknowledge his first three points.

Energy is indeed conserved but convertible in form.

Atmospheric energy contribution is central to analysis of climate and climate change.

Solar irradiance (energy) at the top of the Earth’s atmosphere is 1.36 kilowatts per square metre but this falls due to atmospheric absorption to about one kilowatt per square metre at the Earth’s surface.

His three misconceptions are that:
1. The millions of solar panels absorbing energy to produce electricity would prevent this energy from being absorbed by the atmosphere.

However atmospheric absorption of solar energy begins at the top of the Earth’s atmosphere.

This is generally agreed to be about 100 kilometres above ground.

Solar panels are mounted approximately five metres above ground.

In fact some heat energy is returned to the environment from the solar panels.

Place your hand on the top of a solar panel at midday.

2. Wind energy is also collected from the lowest part of the 100 kilometre thick atmosphere.

Remembering that energy is conserved we find that any losses in the conversion of rotational (kinetic) energy to electrical energy is also returned to the environment as heat from the generator, through heat through current losses in the power lines or used in the home.

3. The vibrational behaviour of the carbon dioxide molecule in the atmosphere causes reflection of the heat from the Earth back to the Earth.

My students compare carbon dioxide in the atmospheric evolution of the planet Venus.

The discussion of this is well beyond the scope of your correspondent’s letter or indeed this response.

I would like to offer your correspondent a place in the current class, ‘An Investigation of the Physical World’, offered by the University of the Third Age at Cavanbah Village (Wednesday mornings weekly).

We are about to begin the study of heat and energy.

We will proceed to energy (kinetic and potential, mechanical, heat, electrical, chemical) then storage including conservation.

The classes feature hands-on exercises and demonstrations every week.


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