Chapter 5:

Alternative Energy Sources

Today we hear endless discussions about “Alternative Fuels”, “Renewable Energy” and Sustainable Energy. 

What are they and how do they differ?

Nations around the world are transitioning to “alternative” or “renewable” energy sources. What are our options on Hawai‘i Island, and which are better than others?

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Hawai`i has mandated that 100% of the power used in the state be generated from renewable resources by 2045. This mandate applies exclusively to electricity and does not include transportation power. Of course, the preference is for as much of our transportation to also be powered by renewable energy. This would come largely from electricity, as well.

We tend to think of renewable power primarily coming from solar panels, wind turbines or giant hydroelectric dams with their water filled spillways. But there are more ways to generate renewable power than those, alone. With fossil fuels ceasing to be a viable option for the future, let’s look at what replacement options are on the horizon moving forward:

Solar Power - is energy derived from the sun. It is the most abundant source of energy found on Earth. Panels made from specialized silicon-based material is able to convert sunlight into electricity. The amount of electricity generated is dependent on weather conditions. The time of day is also a factor as it can only produce during daylight hours; the greatest amount being produced on a clear day, when the sun is directly overhead (around noontime).

Wind Power - is electricity generated when wind is used to cause a large windmill to spin a turbine generator mounted behind its giant fan blades. This method for generating electricity is also weather dependent. Wind turbines are increasingly productive the faster the wind is blowing. If the wind is not blowing or is blowing very slowly, wind turbines will produce little, if any power.

Biomassused for millennia prior to the expanded use of fossil fuels, was the primary fuel source for generating heat. Coming in many forms such as trees, grasses, and other carbon-based plant materials, biomass is a fuel source that collects and stores the energy contained in sunlight. That energy is released in the form of heat when burned. That heat can be used to boil water, creating steam which then serves to spin a turbine power generator that produces electricity.

Hydropower - uses a combination of gravity and the downhill flow of water to spin a turbine generator. Typically, this involves building a dam across a river which stores large quantities of water on one side of the dam. With precisely controlled release, the water passes through a turbine generator to steadily generate electricity as needed over time.

Nuclear Power - plants generate electricity by splitting heavy atoms in a controlled atomic chain reaction to produce heat. The heat is used to make steam that powers conventional turbine generators which produces electricity as its output.

Geothermal - is another natural heat source used for creating steam to generate electricity. In this case, heat is found below the Earth’s surface where the core of our planet remains at temperatures equal to the surface of the sun (6,000o C). Unlike It therefore does not need any external fuel to create its heat.

Biogas - is a byproduct that comes from decomposing organic waste such as food scraps and animal waste. The result is a blend of gases much like common natural gas and is primarily composed of methane and carbon dioxide. Biogas is produced in an anaerobic environment (oxygen free) and therefore can be captured, stored, and used for various purposes including producing heat for electricity or serving as a feedstock for producing hydrogen. Common locations where biogas would be found are landfills and industrial farming operations.

Tidal Power - or tidal energy converts kinetic energy (energy due to motion) obtained from tides into useful forms of power, mainly electricity. The tidal energy is a product of the Earth’s rotation and the gravitational forces exerted upon our oceans by the Moon and the Sun.

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