1.6.1 Sources of Renewable and Non-Renewable Energy
Renewable and non-renewable energy are of two types, in general, on the planet earth used by living organisms.
Renewable energy sources: Renewable energy sources are defined as the energy achieved from natural sources that are continuously produced by themselves for a day-to-day activity usage in a periods of time. These energy systems comprise sun, ocean waves, biomass (wastage of vegetable materials), hydel-power plants, and also some other such resources. This type of energy is also stated as green or sustainable or nonconventional energy sources.
Non-renewable energy sources: Non-renewable energy sources are defined as the fuel that do not rejuvenated itself continuously once utilized on the scale of levels that sustain its rate of consumption. These resources are presented in a larger amount of fixed quantities and used quickly as faster than nature could produce. Some best suitable instances are coal, nuclear energy, fossil fuels, natural gas, petroleum products, uranium, etc.
1.6.2 Differentiate Between Renewable and Non-Renewable Energy Sources
The difference in renewable and non-renewable energy sources was explained in Table 1.5.
Table 1.5 Difference in renewable and non-renewable energy sources.
| S.No | Aspects | Renewable energy | Non-renewable energy |
| 1 | Origin | Earth’s atmosphere— Not human made | Underground layers of Earth-Natural resources |
| 2 | Restrictions | Eco-friendly to use | Serious impact on environment leads to climatic change |
| 3 | Skills | Interdisciplinary | More awareness link with engineering terms |
| 4 | Life of Resources | Finite | Infinite and vanish |
| 5 | Scale | Small | Large |
| 6 | Impacts on environment | 3%–4% of CO2 | 91%–94% of CO2 |
| 7 | Harmful to environment | Less harmful | More polluted to air, water |
| 8 | Requirements of area | Larger | Smaller |
| 9 | Maintenance cost | High | Low |
| 10 | Safety Precaution | Less | More |
| 11 | Examples | Solar, tidal energy, ethanol, biofuels, methanol, biodiesel, etc. | Oil, natural gas, minerals, etc. |
1.7 Photo-Thermal Conversion System
A photothermal system is the direct method where solar energy helps to transfer as incident radiation into heat. Some of the solar collection systems are designed based on this concept that are flat plate collector, evacuated collector, solar air collector, etc.
The basic principles involved in this energy conversion are absorption, reflection, emission, and transmission.
1.7.1 Flat Plate Collector
In any solar collection energy systems, flat plate collector plays an eminent role which absorbs the solar energy and then converted as heat. The heat source may be transferred into the line of a gas or a fluid. Generally, flat plate collector has the following components: absorber, transparent, cove, and frame. Heat passes through the inlet and outlet pipe lines.
Absorber plate: The plate is made up of aluminium, copper, polymeric materials, steel, and duct materials. Some of the basic materials are used with black painted on the radiation receiving sides. The function of absorber plate is to convert heat from short wavelength radiation to minimize the heat loss in a system.
Cover: Cover is made up of materials such as one or combination of more sheets, synthetic foils (i.e., Teflon and Polyethylene). It also helps to arrest the convective heat transfer loss to surroundings.
Collector box: It contains various parts which need for the radiating transmission, absorption, thermal insulation, and energy conversion from a source. The materials used for these elements are aluminium, galvanized steel, wood, and synthetic materials.
The collector designs are categorized into various types that depend upon the