Green Energy Sources

Environmentally friendly and non-polluting sources of energy are gaining a foothold in the international community’s efforts to plan for future electricity needs. Typically, the focus on green energy includes creating a renewable energy portfolio (e.g. bio-fuels, geothermal, wind, hydro power and its related wave and tidal technologies, and solar with some consideration for nuclear power) and energy efficiency. In developing both aspects of a sustainable energy policy the goal is to stabilize and reduce carbon dioxide emissions:

• The renewable energy portfolio provides the long-term solutions to reducing these emissions, and
• Energy efficiency initiatives slow energy demand growth, allowing the “cleaner” energy supplies the time necessary to replace fossil fuel use and avoid unnecessary energy consumption. Failure to place proper emphasis on efficiency will result in “chasing a receding target.”

Green Energy Portfolios

The recent increases in legislative and regulatory attention on green energy sources and energy efficiency has led to significant investments in new technologies that are now becoming main stream. These supply technologies include:

Bio-Fuels: Liquid fuel (Bio-ethanol) that originates from the sugar components of plant materials are becoming more viable as oil prices increase and the need for energy security increases.

Geothermal: Power extracted from the heat stored in the earth, geothermal plants around the world have the capacity to generate 10 GW of electricity or about 0.3 percent of the global electricity requirements. Generally considered cost-effective (once the plant is constructed and sources located), sustainable, and environmentally friendly, geothermal energy offers theoretically more than adequate resources to supply the world’s energy needs, . The costs for drilling and exploration will limit its practicality as a large part of the solution.

Wind: Using wind turbines to create electricity, wind-powered generators worldwide have over 121 GW of capacity (2010) and they satisfy over 1.5 percent of worldwide electricity usage. Wind power has grown rapidly and has doubled between 2005 and 2008. Over 80 countries around the world are using wind power on a commercial basis. Wind power offers an attractive alternative to fossil fuels (plentiful, renewable, widely distributed, clean and produces no greenhouse gas emissions), but due to its appearance it is not always welcomed by local residents.Additionally, the lack of storage and the inability to control poses a challenge as the output must be used as it becomes available, suggesting that wind power may be most optimally deployed as a relatively low proportion of the total demand for electricity.

Hydro power: Derived from the energy harnessed from moving water, hydroelectric power supplies over 19 percent of the world’s electricity. Except for a few countries that have an abundance of hydro power, this application lends itself to meeting peak load demand (easily stopped and started). It produces little (if any) carbon dioxide and its production costs can be far less expensive than other options (particularly fossil and nuclear). Its major challenges lie in the availability of appropriate sites, the cost of construction, and the potential environmental impact of major hydroelectric facilities.

Wave: Not currently a widely used commercial technology (Aqucadoura Wave Park in Portugal consists of just three 750 KW Pelamis devices), wave power involves the transport of energy by ocean surface waves and the subsequent capture of that energy for use.

Tidal: Derived directly from the relative motions of the Earth-Moon system, tidal energy is generated by the interaction between the motion of the water (currents) and gravitational forces. Though not used widely, its potential is vast as tides are more predictable than the sources of wind energy or solar power.

Solar: Either direct (photovoltaic) or indirect (concentrating solar power), solar power is the generation of electricity from sunlight. The power gained from solar power eliminates the need for electricity gained from fossil fuels and to the extent it exceeds residential requirements, can be sold back to the electric utility. Categorized as a predictably intermittent energy source (i.e. though not available at all times its availability can be predicted with a reasonable degree of accuracy), it also can be stored to ensure a level of availability overnight or during periods that sunlight is inadequate to produce electricity.

Nuclear: Nuclear power is viewed by some observers as a sustainable energy source, though the constant attention to avoiding major accidents and the challenges in safely disposing of nuclear waste creates controversy over its role as part of the green energy solution. At worst, nuclear power should be viewed as a hybrid, as it is at least as environmentally friendly as the traditional sources of renewable energy, producing little carbon dioxide emissions; and with continued investment in fusion-related technologies could eliminate a significant amount of concern over the disposal of high level radioactive waste (i.e. spent fuel).