gathering humen energy from body heat

Thermal heat production in humans

Energy in the human body comes from the food consumed . Human daily energy intake nearly equals the daily energy production because there is negligible storage of energy in terms of fat or in growth processes such as that of bone or muscles

After food ingestion , catabolic processes associated with digestion will increase energy production for up to six hours after the time of ingestion . Only digestible food rich in protein and carbohydrates contributes to this increase

The amount of heat produced by an individual depends on

the calories consumed subtracting any mechanical work done . For example 2400 kilocalories can produce 116 watts of energy in a single day

The greatest amount of heat in the body comes from muscle activity . Most of this heat comes from the larger muscles like those of the arms and the legs . For instance during cold seasons this heat is utilized by poikilotherms to warm themselves

The temperature at the body surface of the human being is strongly associated with heat generation

The human body can be compared to a machine which converts fuel into energy to do work . The more active the body is the more energy it will produce . Metabolic rates are used to measure the amounts of heat produced by the body as a result of various chemical reactions . The table below provides examples of activities that generate heat . The figures

are in watts

ACTIVITY WATTS

SLEEPING 81

STANDING 128

WALKING 163

SPRINTING 1 ,630

LONG DISTANCE RUN 1048 On average the human body is capable of producing 11 ,000 watt hours from 15 of fat . The amount of energy produced by an individual is sufficient enough to power electronics if a suitable device is used to convert a fraction of that energy into electrical energy

Heat gathering

Since human bodies eliminate energy inform of heat it then follows that this lost heat can be harnessed and converted into other useful forms of energy using appropriate devices

Thermoelectric materials are capable of converting body heat into electricity by using a combination of materials . In this technology we have poor thermal conductors and good electrical conductors . When these two materials come into contact at different temperatures electrons migrate and this can be used to charge a battery

Thermal energy scavengers

These are electrical generators which can transform the temperature difference between the human body and the environment into electricity

Scientists have come up with the idea of tapping energy from the body and utilizing that energy to power electronics . The energy tapped can be used to charge ipods and mobile phones . The technology involves the use of silicon nanowire- converters whose energy conversion efficiency has been increased by some considerable factor of 100 .The concept emerged from the US Department of Energy Lawrence Bekerly National Laboratory

The major component is created by the process of electroless etching which involves synthesis of arrays of silicon nanowires in aqueous solutions on wafer surfaces . On this surface silicon ions are displaced by reduction of silver ions . The final product of this process is silicon nanowires which have characteristic roughness that is associated with high thermal efficiency

There is also another technology which aims at tapping the heat generated by human beings who are in movement . People moving especially in crowded public places can form a good source of renewable energy

References

Cain , D .F . and Davies , R .E (1962 . Breakdown of adenosine triphosphate during contraction of working muscle . Biochem . Biophys . Res . Commun . 8 361-366

Paul , R . J , Ferguson , D .G , and Heiny , J . A (1993 . Muscle physiology molecular mechanisms . In Physiology (N . Sperelakis and R .O . Banks Eds , pp .189-208 . Little , Brown and Co ...