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	1	+# Redundant thermal energy released by nuclear power plants vs. the thermal energy as provided by the sun
	2	+
	3	+This notebook is a first stab at an approximate calculation to get an idea of the magnitude of the redundant thermal energy that is released by nuclear power plants as compared to that which is supplied by the sun through irridiating Earth.
	4	+
	5	+## Calculate the incident infra-red solar energy at the surface of Earth.
	6	+
	7	+```python
	8	+import math
	9	+```
	10	+
	11	+Earth radius in meters is:
	12	+
	13	+```python
	14	+equatorial_radius = 6378e03
	15	+polar_radius = 6357e03
	16	+```
	17	+
	18	+Approximate Earth surface exposed to solar irradiance can be calculated from  $\pi\cdot r^2$. This can be though of as a disc (plane) facing the sun (i.e. perpendicular to the rays) that is illuminated by sunlight.
	19	+
	20	+```python
	21	+earth_disc_surface = math.pi * equatorial_radius**2
	22	+print('irradated surface area: ', earth_disc_surface,'m^2')
	23	+```
	24	+
	25	+ irradated surface area:  127796483130631.38 m^2
	26	+
	27	+Sunlight's composition at ground level, per square meter, with the sun at the zenith, is about 527 watts of infrared radiation, 445 watts of visible light, and 32 watts of ultraviolet radiation.
	28	+
	29	+<https://ag.tennessee.edu/solar/Pages/What%20Is%20Solar%20Energy/Sunlight.aspx>
	30	+
	31	+```python
	32	+infrared_sol_power = 527
	33	+```
	34	+
	35	+Total solar infrared power available at the surface is thus:
	36	+
	37	+```python
	38	+earth_sol_power = earth_disc_surface * infrared_sol_power
	39	+print('Total power: ',earth_sol_power / 1e12, 'Tera Watt' )
	40	+print('Total power: ',earth_sol_power / 1e15, 'Peta Watt')
	41	+```
	42	+
	43	+ Total power:  67348.74660984274 Tera Watt
	44	+ Total power:  67.34874660984273 Peta Watt
	45	+
	46	+Total energy delivered over a year is thus:
	47	+
	48	+```python
	49	+earth_sol_energy = earth_sol_power * 24 * 365
	50	+print('Total energy: ', earth_sol_power * 24 * 365 / 1e18, 'Exa Watt hour' )
	51	+```
	52	+
	53	+ Total energy:  589.9750203022223 Exa Watt hour
	54	+
	55	+## Calculate the total thermal energy released by all nuclear power plants on Earth
	56	+
	57	+Nuclear energy now provides about 10% of the world's electricity from about 440 power reactors. In 2018 nuclear plants supplied 2563 TWh of electricity.
	58	+
	59	+<https://www.world-nuclear.org/information-library/current-and-future-generation/nuclear-power-in-the-world-today.aspx>
	60	+
	61	+Nuclear power plants usually have efficiency about 33%. In modern nuclear power plants the overall thermodynamic efficiency is about one-third (33%), so 3000 MWth of thermal power from the fission reaction is needed to generate 1000 MWe of electrical power.
	62	+
	63	+```python
	64	+electric_energy = 2563e12
	65	+efficiency = 0.33
	66	+thermal_energy = electric_energy / efficiency
	67	+print('Initial thermal: ', thermal_energy / 1e12, 'Tera Watt hour')
	68	+```
	69	+
	70	+ Initial thermal:  7766.666666666666 Tera Watt hour
	71	+
	72	+```python
	73	+released_energy = thermal_energy - electric_energy
	74	+print('Released thermal: ', released_energy / 1e12, 'Tera Watt hour')
	75	+```
	76	+
	77	+ Released thermal:  5203.666666666666 Tera Watt hour
	78	+
	79	+## Ratio of solar infrared energy and heat released by nuclear power plants
	80	+
	81	+```python
	82	+ratio = released_energy/earth_sol_energy
	83	+```
	84	+
	85	+The ratio of thermal energy released by all nuclear power plants in the world over the period of a year, to the total delivered thermal energy by the sun over the period of a year is given below.
	86	+
	87	+```python
	88	+print(ratio)
	89	+```
	90	+
	91	+ 8.82014744285448e-06
	92	+
	93	+```python
	94	+
	95	+```