# Energy



## Engineer22 (Aug 12, 2017)

energy


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## Engineer22 (Aug 12, 2017)

energy


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## Sheshtawy (Aug 14, 2017)

Electricity used for heating water is an example of high grade energy used to produce low grade energy. High grade energy is the form of energy that can easily be transformed to another energy form. Electrical energy is considered high grade energy as it can be converted completely into thermal energy (a low grade energy). In example number 2, an electric heater can be used to heat water.

I don't thing electricity used in ground source heat pump is an example of high to low grade energy process as the main source of energy in that example is the ground thermal energy (still a low grade energy), the electricity is only used to circulate the water from the ground as in a typical heat pump.


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## Engineer22 (Sep 3, 2017)

Thank you!


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## Engineer22 (Sep 3, 2017)

I read the following:

*The electricity generated by natural gas is used to drive a heat pump and when the outdoor air is above freezing, 71% of the energy in the gas is delivered as space heat.”*


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## Engineer22 (Sep 3, 2017)

I believe this is what I meant.


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## Sheshtawy (Sep 5, 2017)

What makes a type of energy low or high grade is its ability to transform completely to another form. Electricity can be transformed 100% into thermal energy, thermal energy can't be transformed 100% into anything.

You got the general idea correctly. If the question read "high grade energy for a low grade task" then technically electricity is used to heat something (high to low grade), but I still think the ground source pump isn't the MAIN source of energy for heating. The main source is the thermal energy in the ground and the pump is used to circulate the fluid carrying that energy to the colder space. To put it another way, the amount of thermal energy required to heat the space is much larger than the work done by the pump alone, thus it's not the main source of energy and shouldn't be considered an example of high grade energy used for a low grade energy task.


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## Engineer22 (Sep 14, 2017)

This makes sense!!


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## Sheshtawy (Sep 15, 2017)

Yup! You're welcome!


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## Engineer22 (Sep 15, 2017)

Can you clarify


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## Sheshtawy (Sep 18, 2017)

Yes it would


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