Tidal power (tidal energy) facts

Tidal energy is the utilization of the sun and moon's gravitational forces - as the tide is the result of their influences.

Tidal energy is a type of energy that produces electricity and other forms of power through the use of water.

Tidal energy is energy that could be obtained from the changing sea levels. In other words, tidal energy is a direct result of tide shifting from low to high.

Tidal energy is one of the oldest forms of energy. Tide mills, in use on the Spanish, French and British coasts, date back to 787 A.D. Tide mills consisted of a storage pond, filled by the incoming tide through a sluice and emptied during the outgoing tide through a water wheel.

The tide moves a huge amount of water twice each day and although the tidal energy supply is reliable and plentiful, converting it into useful electrical power is not easy.

There are two basic theories on how to convert tides into power. The first involves converting the power of the horizontal movement of the water into electricity. The second involves producing energy from the rise and drop of water levels.

La rance tidal power plant.

Tidal energy is considered to be a renewable source of energy since it only uses the energy from the changing of the tides instead of burning or consuming any form of energy source.

Although the technology required to harness tidal energy is well established, tidal power is expensive, and there is only one major tidal generating station in operation. This is a 240 megawatt station at the mouth of the La Rance river estuary in France.

The major advantage of tidal energy is its economical benefits. For example, tidal energy does not require any fuel. Tides rise and fall every day in a very consistent pattern.

The technology required to convert tidal energy into electricity is very similar to the technology used in traditional hydro-electric power plants - dam, gates and turbines.

There are three prototypes of tidal energy devices: horizontal axis turbine, vertical axis turbine, and oscillating devices.

The cost of tidal energy is very site specific, and influenced by geography, distance to grid, and speed and volume of the current.

The altering of the ecosystem at the bay is the biggest drawback of tidal power. Damages like reduced flushing, winter icing and erosion can change the vegetation of the area and disrupt the balance.

Tidal energy underwater turbine.

Tidal energy is not on the list of sustainable energy technologies the UN agencies even though for islanders it is our best hope for large amounts of affordable clean power.

Stream tidal energy is harnessed from currents – horizontal water movement which is created by the rise and fall of tides.

Turbines, similar to wind turbines, can be anchored to the sea bed to generate electricity from tidal currents.

Tidal energy is at its most efficient where the height of the tide, mass of water being moved, and the speed of its movement are all at their optimum level.

Tidal energy is perceived as having the potential to provide a reliable source of green energy because it is predictable and guaranteed, unlike wind turbines, which are dependent on the weather.

Tidal energy has an efficiency of 80% in converting the potential energy of the water into electricity.

Tidal power can provide secondary benefits such as bridges and roads, which are built over the tidal generators.

Tidal power changes the sedimentation and turbidity (how clear the water is) of the water system.

US solar energy map

US solar energy map. Southeast states are most suitable for solar energy projects. Click on map for full size.

On the picture above is map of US with average annual direct normal solar radiation. If you want to see full size map you should click on this picture. Resolution of this map is resampled to 40 kilometers. Model estimates of monthly average daily total radiation using inputs derived from satellite and/or surface observations of cloud cover, aerosol optical depth, water vapor, albedo, atmospheric pressure and ozone. Dark red are areas with high average solar energy radiation, and those areas are perfect for exploitation of solar energy for generating electricity, warming water, etc. Dark red areas in average are receiving more then 9 kWh of solar energy per square meter per day and that amount of solar radiation is definitely enough for exploitation. Dark grey areas are receiving less than 2 kWh of solar energy per square meter per day in average, and that amount of energy isn’t acceptable for bigger solar energy projects.

Near midday on a clear day, about 25 percent of the solar radiation is scattered and absorbed as it passes through the atmosphere. As a result about 1000 w/m2 of the incident solar radiation reaches the earth's surface without being significantly scattered. This radiation, coming from the direction of the sun, is called direct normal irradiance or direct normal solar radiation. Some of the scattered sunlight is scattered back into space and some of it also reaches the surface of the earth. The scattered radiation reaching the earth's surface is called diffuse radiation. Some radiation is also scattered off the earth's surface and then re-scattered by the atmosphere to the observer. This is also part of the diffuse radiation the observer sees. This amount can be significant in areas in which the ground is covered with snow. The total solar radiation on a horizontal surface is called global irradiance and is the sum of incident diffuse radiation plus the direct normal irradiance projected onto the horizontal surface. If the surface under study is tilted with respect to the horizontal, the total irradiance is the incident diffuse radiation plus the direct normal irradiance projected onto the tilted surface plus ground reflected irradiance that is incident on the tilted surface.

Mojave Desert is the best part of US for solar energy utilization. Click on picture for full size.

From this map we can clearly see that some US states are in very good position for solar energy exploitation. Arizona is without doubt the best located US state for solar energy projects. US states with great solar radiation levels are also California, Nevada, Utah, New Mexico and western parts of Texas. Best parts of California for utilization of solar energy are southeast regions with San Bernardino County as best placed County in California. Southeast California, south Nevada, southwest Utah and east Arizona are in fact the Mojave Desert. The Mojave Desert receives less than 10 inches (250 mm) of rain a year and is generally between 3,000 and 6,000 feet (1,000 and 2,000 m) in elevation. New Mexico is also located on very favorable position for solar energy, but states around Mojave Desert are receiving considerably more solar radiation per square meter than New Mexico. East parts of Texas are also located well for exploitation of solar energy, especially Mexico bordering Rio Grande area. If you look whole US map, then you can see that best solar energy areas are southwest parts of the country. One would think that Hawaii are best placed, but that is not true. Hawaii are receiving half of the amount of solar radiation that are receiving best parts of southeast US per square meter per day in average.

Solar energy – More advanatges than disadvantages

Solar energy is renewable energy source that is expected to become one of the most important renewable energy sources in years to come. Solar energy efficiency depends on available sunlight which varies considerably, not only because of differences in cloud cover and latitude but also with the seasons as in the summer significantly longer daylight hours combined with higher sun angle provide much more solar power than in winter when day is short and sun is positioned low in the sky. Through this article I will compare advantages and disadvanages of solar energy.

Solar dish system used for water heating. Click on picture for full size.

Solar energy has rather large investment costs because of the high cost of the semi-conducting materials that are used for building solar energy systems and therefore its investment costs are significantly larger compared to for instnce, electricity that is gained from non-renewable energy sources. Thre's also the great problem in required area for this installation since solar panels require very large area in order to achieve optimum efficiency. With size of the area, there's also the problem of location, since system efficiency also depends upon sun location.

Another problem can be clouds or even air pollution since both of them influence intensity of sun's energy. Another problem is nightime of the day when there's no sun in the sky. These look to be serious disadvantages but what about advantages of solar energy, are they big enough to justify installment of solar energy system?

First of all solar energy systems are almost maintenance free and in corelation with free sun energy make excellent long term investment once they start refunding. The recovery sometimes isn't that long as many predict and depends on on how much electricity your household uses. In many countries there are also significant financial incentives that are quite helpful in reducing your investment costs. There's no more electricity bills coming each month and solar energy doesn't require any fule to operate and this is in fact double advantage since it's not affected by the supply and demand of fuel that is now more expensive than ever before. Once you install solar energy system savings are immediate and for manymore years to come.

But not only you will benefite from solar energy, but also your surrounding environmnet since solar energy is clean renewable energy source unlike coal and oil, and isn't causing worsening of global warming problem like non-renewable energy sources do, on the contrary it contributes to decrease of greenhouse gas emissions. There's also none waste disposal problem that is typical for some other non-renewable energy sources.

Solar power plant. All mirrors reflect solar radiation to the top of the tower. Click on picture for full size.

Also if you're looking for indepenent system then solar energy system must be your first pick since solar energy system can operate completely independent, not requiring a connection to a power or gas grid at all which means that this system can be even installed in remote areas where other energy sources aren't neither practical nor available.

So what's the conclusion? There's definitely lot more advantages than disadvantages, not only from efficiency and cost reduction but only in form of preserving the environment, and since the global warming problem started environment became hot issue.

Biomass energy facts

Biomass is all plant and animal matter on the Earth's surface. Biomass is anything that is alive. It is also anything that was alive a short time ago.

Biomass gets its energy from the sun. Plants store the sun’s energy in their leaves and roots. Then animals eat plants and other animals to move and grow. The energy of the sun is 'captured' through the process of photosynthesis in growing plants.

Biomass energy is renewable, which means we can make more biomass in a short time. We can always grow more plants.

Biomass can be used to make electricity. Many towns burn their garbage in waste-to-energy plants. Instead of putting the garbage in landfills, they burn it to make electricity.

Biomass can be used to make an energy-rich gas called biogas. Biogas is like the natural gas we use in our stoves and furnaces.

Biomass is found in forests, fields and barns, in industrial and manufacturing facilities, and in landfills. Click on picture for full size.

Biomass can also be turned into a fuel like gasoline. Just as apples can be made into cider, corn and wheat can be made into ethanol. Ethanol is a fuel a lot like gasoline.

Biomass is part of the carbon cycle. Carbon from the atmosphere is converted into biological matter by photosynthesis.

Biomass is a sustainable and potentially environmentally sound resource.

Biomass is considered to be one of the key renewable resources of the future at both small- and large-scale levels. It already supplies 14 % of the world’s primary energy consumption.

With increases in population and per capita demand, and depletion of fossil-fuel resources, the demand for biomass is expected to increase rapidly in developing countries

Growing biomass is a rural, labour-intensive activity, and can, therefore, create jobs in rural areas and help stem rural-to-urban migration.

Extracting energy from biomass is an ancient practice, dating back to when people first burnt wood to provide heat and light.

Most biomass is in solid form, but it can also be a liquid. Biomass usually consists of a complex polymer of carbon, hydrogen and oxygen with small amounts of nitrogen and inorganic elements.

Biomass is not fossilised material (like oil, coal and gas) but fresh material that can grow again after having been harvested.

Modern biomass is used to produce power and heat in large-scale facilities: solid biomass, biogas, biofuel or biodiesel.

Using biomass as a fuel means that carbon dioxide (CO2) which was absorbed from the air while the plant was growing, is released back into the air when the fuel is burned. The system is said to be carbon neutral.

Biomass power or biopower is the use of biomass to generate electricity, or heat and steam required for the operation of a refinery. Biopower system technologies include direct-firing, cofiring, gasification, pyrolysis, and anaerobic digestion.

The forest biomass is currently the most expensive fuel for the power plants and the market structure will not support transport of much more than 50 miles from the forest to the biomass powerplant.

Geographic Distribution of Biomass Crops in the US. Click on picture for full size.

Example of biomass energy usage in US: Washington biomass is already producing electricity, steam and fuels while creating jobs from clean, sustainable sources of energy.

Biomass is the top candidate for oil equivalents, and indeed biodiesel has been getting more attention of late as a renewable and low-net-carbon method of fueling vehicles.

Biomass is becoming increasingly interesting as a source of heating for rural districts. Biomass will be the most important fuel for rural households particularly in their cooking and agriculture activities such as crop drying.

Like crude oil refining, it is expected that plant biomass will be fractionated into its different component parts, which will then be used for the production of a wide variety of fuels, materials and fine chemicals.

According to trials happening in Japan, if the biomass is going to be transported in from 200 km away, the amount of energy needed to transport the biomass is going to be larger than the energy that can be produced.

The manufacturing related to biomass is going to happen where biomass occurs. Biomass occurs in rural areas meaning more manufacturing jobs in rural areas.