Wind, solar and hydropower are by far the
most common and popular sources of renewable energy. However, as the definition
of renewable energy includes sources that can be narually replenished on a
human timescale. So even though some of the below mentioned sources of
renewable energy are known to emit greenhouse gasses GHGs, the fact that they
are not reintroducing fossilised carbon into the atmosphere means that they are
still considered renewable.
Biomass
By producing electricity by burning wood
and other organic matter, biomass energy is very carbon intensive. However, the
carbon that is released can also be re-absorbed quickly and re-burned in the
same generation plant completing a renewable cycle.
Biowaste
Biowaste energy is created during the
processing of household and other industrial wastes. In the most common form,
methanol or ethanol is produced through natural decomposition processes which
in turn can be captured and burned.
Pumped Storage
Pumped storage power can blur the lines
between renewable and non renewable energy. In essence, water is pumped to a
higher elevation, only to be released through turbines during times of peak
electricity consumption as the system demands it. Pumping the water initially
requires more energy than is reclaimed during the generation phase, so there is
a net loss of energy. However, if energy from renewable sources is used during
times of low demand, when there would otherwise be a surplus of produced
energy; these systems can be fully renewable and an effective means of
balancing grid supply and demand on grids with a high penetration of
renewables.
Ocean Tidal
This form of renewable energy is still very
much in a development phase, though there are already commercial, grid
connected plants in operation or planning. Using the tidal currents and flows
in areas where this can be strong such as in inlets and estuaries, the power of
the sea can be used to power the electrical grid. There are numerous challenges
which still need to be overcome to successfully deploy this power source on a
wide scale, but the potential is great.
