Indirect vs Direct
Solar energy can be categorized into two: direct and indirect. Direct solar energy involves only one step between sunlight and functional use. For example, sunlight is processed by solar energy systems to produce electricity or heat. On the other hand, utilizing indirect solar energy involves a number of steps.
Technically, the fossil fuels we process to produce heat and electricity are forms of indirect energy resources. They are derived from ancient biological material which millions of years ago took energy from the sun. However, the carbon from these fossil fuel resources have been out of the carbon cycle for a long time. This is why indirect solar energy usually relates to resources like biomass, wind, and water.
Indirect Solar Energy / Biomass Energy
Biomass energy relies on biological material that use or recently used photosynthesis to produce chemical energy from solar energy. The chemical energy produced can then be used as fuel for electricity generation.
Materials used for biofuel technology include forest residue, biodegradable waste, and animal or plant matter. Some plants are even grown specifically for use in industrial biomass energy production. The biomass used to generate biofuel is not particularly important but it does affect the way it is processed.
The main advantage of using biomass energy is that it involves low levels of pollutants. However, processes to generate and distribute it involve high land and water use. It also increases risk of deforestation and desertification.
Indirect Solar Energy / Wind Energy
In wind energy systems, wind is processed through turbines whose blades rotate because of airflow. As the blades rotate, drive shafts are spun by gears and power a generator. The generator then sends electricity to nearby utilities.
Generating and utilizing wind energy does not involve harmful wastes or emissions. However, it does pose a threat to populations of birds and bats but this issue can be addressed by keeping turbines away from migratory pathways and turning them off during migration periods.
Indirect Solar Energy / Hydropower
Hydropower relies on water that precipitates into the Earth as rainfall because of evaporation from the sun’s heat.
Although hydropower is a renewable and sustainable source of energy, using it causes changes to the natural flow of rivers, disrupts migratory fish patterns, and keeps silt away from farmlands. It may also cause earthquakes because of reservoir-induced seismicity. Furthermore, it can become a source of water diseases that can easily spread downstream. Lastly, dams are expensive to build and maintain.
There are other indirect energy resources in use today and serve as better alternatives to fossil fuels. However, like biomass energy, wind energy and hydropower, the processes used to generate them pose some potential risks to the environment.
Direct solar energy, then, provides greater potential when it comes to renewable and sustainable energy resources as it does not produce harmful waste or emissions and it does not affect wildlife and natural processes. Furthermore, utilizing direct solar energy is more efficient and technologies are much easier to maintain.
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