Introduction to Renewable Energy

Simply defined, renewable energy is energy that emanates from natural resources (e.g. sunlight, wind, and tides) which can be naturally replenished. There has been a significant push since the start of the 21^st century to incorporate these sources of energy into an overall portfolio. By 2008, 19 percent of global energy consumption was satisfied by renewable energy sources. The main drivers of the ongoing trend toward increased government spending and regulation to support the further development and commercialization of these technologies include:

• Concerns over climate change,
• High oil prices, and
• Current thinking with respect to peak oil.

Uses of Renewable Energy

There are a number of areas where renewable energy replaces the more conventional sources of fuel, namely:

• Generation of Electric Power. Renewable energy provides 18 percent of the generation of electricity worldwide.
• Heating. Over 70 million households worldwide have their hot water needs met by harnessing the sun, and in Sweden the use of biomass has surpassed oil as the primary source for heating.
• Transport Fuels. Bio fuels has replaced 5 percent of the gasoline, or 68 billion liters, produced to support transportation needs.

Forms of Renewable Energy

The following discussion summarizes some of the more traditional forms of renewable energy:

• Wind power, growing 30 percent annually, is generated from wind turbines where the most common ones have rated output between 1.5 and 3 MW, with wind speed being the primary variable in determining available power. There is every reason to further invest in this technology as current estimates state that potential for wind energy is five times that of global energy production or 40 times the current electricity demand. Of course, trade-offs regarding use of land or offshore locations will have to be made as the size of a wind farm footprint for comparable output is significantly larger than that of a conventional fossil or nuclear plant.
• Hydro power is generated from the harnessing power of water through dams or the natural movement of water in oceans and rivers. Though hydropower represents the largest percentage of renewable energy worldwide, from a future growth perspective, depending on the region, it is leveling off and even decreasing in its role as a major participant in the overall energy solution.
• Solar power. As it name implies, solar energy is derived from the sun and depending on the specific technology, can capture the energy either actively, using photovoltaic panels or passively by orienting the building to absorb / collect the sunlight.
• Biomass. The energy contained in plant material can be captured through the process of photosynthesis and stored for subsequent use. The main approaches in using these plants are to either grow them specifically for this application or use the residues of plants used for other purposes.
• Bio fuels. Liquid bio fuels are either bio-alcohol (e.g. bio-ethanol) or oil (e.g. bio-diesel). In the case of bio-alcohol, the source plant materials are typically sugar and starch crops, and the resulting ethanol is usually used more as a gasoline additive to increase the octane value and decrease emissions than as a primary fuel. The comparable product, bio-diesel, uses vegetable oils and animal fats, and like its ethanol counterpart, is typically used as a diesel additive, but to reduce levels of particulates, carbon monoxide and hydrocarbons.
• Geothermal energy. Obtained by using the heats at the earth’s core, geothermal power stations are expensive to build yet relatively inexpensive to operate. This core is closer to the surface in some areas than in others translating to higher feasibility in producing cost-effective power. Specific “Geothermal Friendly” areas include Chile, Ireland, New Zealand, the Philippines, and in the U.S. Yellowstone basin and Northern California.

Where as newer and emerging technologies are being explored for possible commercialization:

• Cellulosic Ethanol. Though the by-product is still ethanol, research and development is currently being conducted around shifting the focus from food crop to waste residues and grass, and producing enzymes that will enable cellulosic ethanol.
• Ocean energy. The potential to harvest electrical power from the ocean looks particularly promising on coasts facing the west within latitudes between 40 and 60 degrees. Technologies to harness tidal power or use the temperature differences between deep and shallow waters are in various forms of development and application.
• Enhanced Geothermal Systems. This developing technology does not require natural hydrothermal resources, and may therefore be possible anywhere in the world. There are still limitations, just not as many, as locations should be over deep granite covered by a fairly thick layer of sediments for insulation.
• Nanotechnology Thin-Film Solar Panels. With the ability to create circuits out of individual silicon molecules, this technology is still in the R&D stage, but if successful, may be half the cost of the more traditional PV cells.

Growth and Economics of Renewable Energy

In consideration of the main drivers for renewable energy, the variety of uses and the spectrum of technologies already developed and being developed, capacity related to renewable energy has grown significantly since 2007:

• Investment in new renewable energy generation was $150 billion worldwide in 2009, as compared to $107 billion in 2007.
• Overall capacity of renewable energy has increased 15 percent to 1,230 GWe, with significant increases of 70 percent in wind power, 300 percent in solar PV, and 50 percent increase in ethanol during this same 2-year period.
• Excluding large hydro power plants, the increase in renewable energy generating capacity has increased 27 percent to 305 GWe.

Though appearing initially expensive, with time renewable energy becomes less expensive while fossil fuel alternatives generally realize increases in costs:

• Once a renewable infrastructure is constructed, the source is virtually free.
• As renewable energy technologies improve, innovation inherent to these more vibrant capabilities will lead to increased efficiencies, thus reducing their cost.
• With overall increases in production volume, the unit costs of wind turbines and solar