Renewable Energy
Anthony Rommens
27-Nov-06
The energy sector has been featured in the press this year because of rising consumer electric and petroleum prices. There is much international speculation over securing supplies in the world markets. Sector investments may be of interest to business angels since demand is so massive. We explore Renewable Energy and answer the basic questions, “What is Renewable Energy?” and “What are the various types?”.
Renewable Energy is power from sources that are not destroyed when energy is released. Renewable Energies are usually harnessed from nature’s forces of Sun, Wind, Water, Plants and Geological Heat. Humans have utilised Renewable Energy for centuries but only recently produced electrical and automobile power with it. Renewable Energies are from largely sustainable sources rather than limited supplies. Fossil Fuels like Coal or Petroleum produce greenhouse gases and air pollution and thus are not considered “Renewable”.
Nuclear power is generally not considered because it does not meet traditional definition conventions. Some political advocates for nuclear power try to label it as ‘renewable’ but Nuclear by-products are hazardous and there are significant problems storing the radioactive waste for indefinite periods of time. The term “Renewable Energy” was created in the 1970’s to clearly exclude Nuclear power from the definition. No legislative body has yet included Nuclear power under any legal definition and also no Renewable Energy program has supported Nuclear power initiatives.
Categories of Renewable Energy are:
SUN
Solar power refers to that energy collected from the sun. The sun’s energy has historically not been harnessed by mankind until recent however various world cultures have taken advantage of it through proper orientation of walls, windows and architecture features (aka ‘passive solar’ power).
In recent times, sophisticated solar power consists of more scientific ‘passive solar’ power , ‘active solar’ power, and electrical conversion technologies. ‘Active solar’ refers to heat capture with mechanical systems. Examples of ‘active solar’ are homes water heated with water tubes circulating on roofs and also siding materials designed to attract and transfer air heat to the inside of buildings. Electrical conversion consists of Photovoltaic (PV) solar cells that transfer light to Direct Current (DC) electricity that can be used to run electrical devices or recharge batteries. Common solar powered pocket calculators are a simple example of PV technology.
Large applications require big solar cells to be put together in solar panels. Examples of large solar panel arrays are found on various watercraft and buildings. The Solar panels are manufactured by well know international companies such as BP, Shell, Sharp, and Kyocera.
It should be noted that the production of PV arrays are expensive. This makes the PV panels costly for the average consumer however UK residents can apply for grants to help offset the cost of a solar power system.
Applications for government grants under the Low Carbon Buildings scheme are assessed using criteria laid down by the Department of Trade and Industry. Most householders will have to achieve energy efficiency standards before they are eligible. The Energy Saving Trust, which administers government grants, calculates that a system for an average-sized house would cost between £8,000 and £18,000, and yield annual savings between £75 and £125.
Note that some electricity supply companies will buy back any excess electricity generated by the panels.
Although sales of home solar panels have increased in Britain especially over the last few years, they remain far behind that of other European countries.
The sun never provides constant energy exposure. For cloudy days or night use of electricity, the solar power needs to be stored in batteries. Energy loss occurs when storing. Using solar power for Alternating Current (AC) homes also requires solar electricity to be converted from Direct Current to AC currents.
As technology advances, more constant Solar Space power could be generated from satellites and sent to earth via microwaves. Solar power technology is rapidly being developed by start-up companies in America’s Silicon Valley. Progress in Solar power is predicted to be the next big technology wave. There are a variety of Photovoltaic methods for converting sunlight into electricity. Progress is required for low cost manufacturing of Solar Panels, increasing their efficiency, and also utilising advances with actual building materials.
Sun power remains an inexhaustible supply of energy with no environmental pollutants. There still is much potential to develop and grow the industry in Great Britain.
WIND
The suns heats up the earth unevenly and as a result winds are created. Wind Power has been used by man for several hundred years for milling grains, pumping wells, irrigation, and even drainage. New Windmills also create electricity and make Wind Power today’s fastest growing Renewable Energy. Wind can be used to turn power turbines, having two to three slow moving blades to produce electricity up to 5 MW. These turbines usually require a minimum wind of 20 km/h or 5.5 m/s to turn.
Wind strength tends to vary and is not consistent. There are only a few lands that have steady enough winds. Electricity can be produced on average only about 25 to 35% of the time. As a result a 1,000 MW wind generation capacity can be relied upon for 333 MW of continuous power.
At high altitudes and on the ocean, winds are much more consistent and can produce about 90% more wind power than on land. High altitude or airborne windmill technology thus should clearly be a future focus.
Wind Power alone is able to create over five times the Planet’s current energy consumption! To achieve maximum output, it would require about 13% of all land area having about six windmills per square kilometer and they would need to be located at high altitudes of at least 80 meters.
Wind power is an excellent compliment to existing electrical power grids. Many new projects for wind farms are being planned across the globe and the long-term potential of using today’s wind energy is 40 times that of current worldwide electrical demand. Great Britain has one of the highest Wind Power potentials in Europe. The UK has a total potential of 1,000 TWh (50TWh on land) of electricity each year which is about three times its current electricity usage.
WATER
Water energy can be harnessed by capturing its motion or temperature differences. Even slow moving water provides great amounts of electricity. Water energy includes:
Hydro Power This is power from damming up water and capturing its vertical flow. It has been exploited on a large scale around the world and thus probably is not a big option for future energy development. There are many concerns over environmental impacts in using this technology.
Tidal Power Electricity can be produced by two different types of motion. The Vertical push of water from rising and falling tides can turn turbines that let water escape inland basins thus generating electrical power.
Tidal Streams also move underwater horizontally and this motion can be captured via underwater propellers and therefore generated into electricity.
Tidal Power requires significant development capital and there are already some pilot projects operating with current electrical grid systems.
Wave Power Electricity can be created from up and down wave movements with large pontoons floating on the water surface. There are some small projects in operation world wide and further development is required.
Blue Energy Developed largely in the Netherlands, Blue Energy is electricity made by removing salt from seawater through a special electric producing membrane via reversed electro dialysis that separate positive and negative ions. Less salty brackish water is produced. Electricity has been produced on small scale and is still being researched. Further large scale testing of low cost membranes is required. Over one third of the Netherlands power may be produced from Blue Energy if tests and research prove successful.
Ocean Thermal Energy Conversion
OTEC uses cyclic heat engines to make power by taking advantage of temperature differences of the warmer top ocean and the much cooler bottom. This technology has not been tested on large scale.
Lake Water Cooling
This is not really an energy production method but saves power by utilising cold lake bottoms that can be used to cool summer houses via water circulation systems.
BIOMASS
Biomass is living or recently living biological material that is burned or combusted to produce energy. It is originally sun energy converted by plant photosynthesis into chemical energy and may be usable in several forms; Solid Bio-matter, Liquid bio-fuels, and Bio-gas.
Solid Bio-matter
Mankind has used solid bio-matter in fire for centuries. Common examples are charcoal, wood or dried dung. Solid biomass may be burnt to drive generators to produce electricity. Dried Peat is often burnt in the UK but is not considered a renewable energy because it is essentially a fossil fuel that pollutes similar to burning Coal where Carbon Dioxide is released into the atmosphere. Solid biomass can be somewhat harmful to the environment because a lot of input can be expended to create it.
Liquid Bio-fuels
Liquid Bio-fuels may be from bio-alcohol (ethanol from corn), bio diesel and virgin vegetable oils. These can all run with little or no modification on diesel engines. The first autos were actually made to run on vegetable oils. The European Union plans to add 5% bio-ethanol to Petrol by 2010.
Bio-diesel is an alternative to petroleum for diesel engines. It can be made from vegetable oils, soy, sugar beets, and/or corn. Bio-diesel can also be made from soybean or Canola oils, animal fats, waste vegetable oils, or micro algae oils. Bio-diesels are nontoxic, biodegradable, and tend to burn up to 40% cleaner than petroleum. Growing crops require significant time and investment. It is still more expensive than petroleum to produce.
Bio-gas
Bio-gas is produced from decaying organic materials (anaerobic digestion or fermentation). Garbage landfills need to vent this landfill gas to prevent explosions. Animal manure releases methane gas from anaerobic bacteria. Many organic materials like wood can also produce gas under high pressures.
Bio-gas can be produced from current biodegradable waste in pulp & paper manufacturing, animal waste, landfills, and sugar production. Bio-gas can also be produced from combining various wastes. Current sewage plants can be modified into bio-gas plants. After processing methane from plants, the remains are often better fertiliser than the original biomass. Upgraded bio-gas may be added directly to existing natural gas grids.
GEOTHERMAL
Geothermal is that energy from the heat of the earth. This can be obtained just bellow the surface or many kilometers underground. There are several ways to harness this heat.
Geothermal Heating and Cooling (AKA: geoexchange, heat pump, ground-source heating) of buildings can be accomplished by exchange pipes in the ground just bellow the frost line. Over 50% of the sun’s heat energy is constantly absorbed bellow the ground surface. The temperature of the earth crust has a constant 45 to 58 degrees Fahrenheit so fluids can be circulated and pre-cooled or heated through underground pipes providing cooling in the summer and heat in the winter. This technology is constant, renewable but has not been taken advantage of in the UK as there are only about 50 systems installed (thousands are operating in other countries with similar climates).
Heat from the inner core of the earth can be made into usable power and electricity by harnessing underground steam or water. This type of geothermal power is popular in geologically unstable parts of the world where the earth’s core heat is closer to the surface. Examples are found in Iceland, New Zealand, parts of the United States, the Philippines and Italy. Volcanic Iceland heats 86% of all its homes and there is still much potential to be exploited. It also produces just under 20% of its electricity from Geothermal plants.
There are varied methods used to produce electricity, depending on locale. They range from extraction of energy at both shallow and deep drilled depths. There are several types of power plants that include: Dry Steam, Flash and Binary. Dry Steam takes steam from escaping ground fractures to drive turbine generators. Flash plants turn rising hot ground water to steam driven turbines. Binary power plants produce electricity from generators turned by hot water heat exchanges of boiling liquids. The earth has so much heat that no more than a tiny fraction of it is removed even if most of the world’s energy came from geothermal sources.
In conclusion, the key to using sun, wind, water, biomass, and geothermal renewable energy sources is to initially supplement damaging fossil fuels and to not only utilise the technologies together but to also strive towards greater overall energy efficiency as well
