California new tougher renewable energy goals

On Thursday September 23, 2010 CARB (California Air Resources Board) approved in a vote the new goal to raise the state's renewable energy target to 33 percent by 2020 from previous 20 percent by 2010.

As usually the new law impose some controversy. While environmentalists say the goals are too low, the large-scale developers say they are too high. Industry professionals indicate this target as more achievable than a prior goal, however it requires faster approvals for plans and ongoing governmental financing support. 

The new target would boost the renewable energy industry but is facing the significant challenges, as the new initiative in November election may revoke the new law and also the state's governor has the right to suspend provisions of the law for up to a year. 

Proposition 23 (Anti-Renewables Ballot), if approved, would suspend AB 32 CA State laws requiring major polluters to report and reduce greenhouse gas emissions that cause global warming until unemployment rate drops below 5.5% or less for full year. 

Supporters of the prop 23, including oil companies, fight for jobs and economic stability as a cover (but think and ask yourself could it be really true?) and don't care about the environmental protection as AB 32 "The Global Warming Solutions Act of 2006" was intended to protect California from human caused global warming. 

AB 32 is the first comprehensive climate change law in the United States that established the goal of reducing California's statewide greenhouse gas emissions to 1990 levels by 2020, a reduction of approximately 12.5% from current levels and 40% from business-as-usual in 2020.

"We must resist the efforts of out-of-state oil companies to roll back one of the most important environmental protection laws California has ever enacted and one that will serve to increase investment in energy efficiency, produce jobs, and stimulate growth within the state of California," said commission President Michael R. Peevey. "Suspending AB 32 would reverse the regulatory signal to invest in clean, environmentally friendly resources. If this were to occur, customers could face significant carbon abatement costs when AB 32 or federal regulation forces the inclusion of a carbon price into the price of the power. Delaying action now will make it more expensive to reduce greenhouse gases in the future."

The California Public Utilities Commission CPUC has voted to oppose Prop 23 on the following grounds:

1. California is a leader in economically viable environmental protection. AB 32 is one of the most ambitious climate change laws in the U.S. From energy efficiency to renewables, California has taken a leadership role in many of the technologies and strategies that will reduce greenhouse gas emissions, while providing secure, affordable power to its citizens.

2. Proposition 23 will suspend the implementation of AB 32 indefinitely.

3. The indefinite suspension of AB 32 will cause investment dollars currently being spent in California to retreat to other states halting the largest growth industries in the state and stunting job growth.

4. Regulatory uncertainty caused by the indefinite suspension of AB 32 will undermine energy markets, potentially increasing the cost of electricity for consumers.

5. The evidence of the predicted deleterious impacts of climate change is more conclusive than the purported injurious impacts of AB 32.

Read more at http://docs.cpuc.ca.gov/PUBLISHED/NEWS_RELEASE/123814.htm

On August 23, 2010 CARB also adopted goals for reducing greenhouse gas emissions in 2020 and 2035 associated with passenger vehicle travel, for more healthy and sustainable communities that improves the way we plan and promotes more transportation choices. 

Southern California will have to reduce emissions by 8% by 2020 and 13% by 2035, while the Sacramento Region will have to reduce emissions by 7% by 2020 and 16% by 2035. More at http://www.arb.ca.gov/newsrel/newsrelease.php?id=154

California's energy sources in 2008 according to California Energy Commission were: 

✓ Natural Gas 45.7% (with In-State generation 87%)

✓ Coal 18.2% (with In-State generation 7%)

✓ Nuclear 14.4%

✓ Large Hydro 11.0%

✓ Renewables 10.6%

Crude Oil In States source in 2008 was 38%

Forcing more renewable power to be generated in California, would decrease our dependency on foreign oil, reduce the greenhouse gas emissions, and promote the creation of green jobs in The Golden State--direct and indirect.

On September 23, 2010 CPUC (California Public Utilities Commission) took another step towards State's renewable energy goal.  

They approved a 25-year power purchase agreement (PPA) for PG&E (Pacific Gas and Electric Company) with First Solar, Inc. for generation from the 300 MW PV Desert Sunlight project that will deliver approximately 619 GWh of energy annually begining in July 2015, as well as 12 renewable energy contracts for SCE (Southern California Edison). 

12 PPAs were executed as part of Edison's 2009 Renewables Standard Contract (RSC) Program for renewable energy projects under 20 MW to provide a streamlined procurement process for smaller renewable energy projects. The total renewable capacity will be approximately 180 MW. Two of the projects are existing landfill gas facilities, eight are new solar photovoltaic facilities, and two are new wind facilities. 

First Solar is pursuing a Department of Energy loan guarantee under the American Recovery and Reinvestment Act for the project. The proposals voted on are available at http://docs.cpuc.ca.gov/PUBLISHED/AGENDA_RESOLUTION/123619.htm (PG&E) and http://docs.cpuc.ca.gov/PUBLISHED/AGENDA_RESOLUTION/123743.htm (Edison).

The CPUC's Renewables Portfolio Standard (RPS) program requires investor-owned utilities, energy service providers, and community choice aggregators operating in California to obtain 20% of their retail sales from renewable energy sources by 2010 and 33% by 2020. 

In 2009, PG&E served 14.4% and Edison 17.4% of their retail sales from renewable energy sources. RPS Quarterly Report for the 3rd Quarter 2010 is available at www.cpuc.ca.gov/PUC/energy/Renewables/index.htm.

More at http://docs.cpuc.ca.gov/PUBLISHED/NEWS_RELEASE/123806.htm

CPUC authorized SCE (Southern California Edison), PG&E( Pacific Gas and Electric Company), and SDG&E( San Diego Gas & Electric Company) to own and operate solar PV facilities (UOG) as well as to execute SPPAs with IPPs (independent power producers) through a competitive solicitation process. These programs will provide up to 1,100 MW of new solar PV power in California over the next 5 years that will be RPS-eligible. More at http://www.cpuc.ca.gov/PUC/energy/Renewables/Utility+PV+Programs.htm

What Sustainable Means

"Sustainable" has such a comprehensive meaning. 

Among other means it involves:

- environment protection, including people, flora-green plants and fauna-animals, extinction of species; 

- water conservation and reservoirs protection; 

- air & environmental quality (indoor and outdoor); 

- land preservation, including land use, habitat destruction, and intensive farming; 

- pollution prevention (including air, water, soil and land, light, noise, thermal, radioactive, littering); 

- ozone depletion stopping; 

- GHG-greenhouse gas emissions decrease that leads to global warming, slowdown of thermohaline circulation - large-scale ocean circulation or global dimming - reduction of direct irradiance at the Earth's surface; 

- land preservation that covers urban sprawl, habitat destruction and fragmentation, desertification, soil erosion and contamination; 

- ocean protection against acidification, deoxygenation, dead zones, and sea level rise; 

- energy efficiency and conservation; 

- resources preservation (energy resources, such oil and other fossil fuels, but also fishing: overfishing, cyanide fishing, shark finning, whaling; logging: clear-cutting & deforestation; and mining); 

- renewables; 

- ecotechnology; 

- toxins production elimination (dioxin, toxic heavy metals, toxic waste, herbicides, pesticides, CFCs-chlorofluorocarbons, DDT-dichlorodiphenyltrichloroethane pesticide, PCBs-polychlorinated biphenyls);

- waste management (landfill, litter, marine debris, medical waste, leachate, incineration, e-waste, including computers, phones &TVs,  hazardous waste, such batteries, paints, motor oils, pesticides, aerosols, refrigerants, thermometers and fluorescent lighting);

- recycling and reusing;

- environmental health that involve airborne diseases, like asthma, chemical poisoning, radiation, sick building syndrome, and all kind of medical conditions;

- other human activities that encompass genetic engineering, nuclear issues, nanotechnology - nanopollution & nanotoxicology, and overpopulation. 

The list can go on and on with more details.

Let's not forget also about our consumerism, over-consumption and obsolescence.

With all the green trends nowadays I am sure we'll throw most of the non-green products right away, instead of trying to utilize it as far as possible, since we already have it. One of the eye-opening, simply said, and informative stories can be watched at http://www.storyofstuff.com

It took us years and years to get to the point we are now and we are unable to fix everything at once. That's why we all need to be cautious, aware, act with common sense and see a big (or even bigger) picture in order to sustain and survive.

US Largest 62MW Solar Power Development & Solar Ramp-Up Law Signed by IL Gov Quinn

Illinois Governor Patrick Quinn announced over $4 million stimulus grant award for 62 MW Rockford Solar Project, the largest photovoltaic (PV) solar development in the Midwest and one of the largest in the United States at the ribbon-cutting ceremony of Wanxiang America Corporation's newly built solar panel manufacturing plant in Rockford, IL on August 17, 2010.

Illinois Governor Pat Quinn has cut the ribbon to officially open the largest in the Midwest and one of the largest in the USA solar developments, 62MW Rockford Solar Project

62 MW PV system operating an average of 5hrs a day for 365 days will produce approximately 113,150,000 kWh of electricity and reduce the impact on the environment in comparison to traditional power plants burning fossil fuels.

62 MW Rockford Solar Project will generate enough electricity to power over 10,000 homes and reduce carbon dioxide emissions at a rate of 113,000 tons annually, equivalent to the emissions from nearly 12,000,000 gallons of gasoline consumed and the sequestration of 24,000 acres of established forest per year. The Project will decrease ultra-fine particulate emissions, such as Nitrous Oxides (NOx), Sulfurous Oxides (SOx), Mercury and Soot that cause adverse health effects and acid rain in the amount of 51 tons per year. Rockford Solar Project will also contribute to the fresh water conservation in the amount of about 113 million gallons annually. Moreover the project will significantly help utilities achieve the required 0.5% solar target by 2012.

Carbon dioxide (CO2) is one of the Green House Gases (GHG), main contributors to the global warming. GHG’s form in the atmosphere, trap the heat and the  infrared radiation and cause warming the earth like in a greenhouse. The majority of the GHG soar is from human activity, like burning fossil fuels, industrial production, transportation, deforestation, etc. The GHG emissions has to be seriously reduced to protect our environment, our health and economic well-being.

The reduction of 113,000 tons of carbon dioxide CO2 is an equivalent to an annual greenhouse gas emissions from circa 20,000 passenger vehicles, or carbon sequestered by around 3,000,000 tree seedlings grown for 10 years, or greenhouse gas emissions avoided by recycling nearly 35,000 tons of waste instead of sending it to the landfill.

More equivalents of the 113,000 tons of CO2 reduction:

CO2 emissions from 238,400 barrels of oil consumed

CO2 emissions from 1,369 tanker trucks’ worth of gasoline

CO2 emissions from 12,441 the electricity use of homes for one year

CO2 emissions from 8,724 the energy use of homes for one year

Carbon sequestered annually by 21,858 acres of pine or fir forests

Carbon sequestered annually by 973 acres of forest preserved from deforestation

CO2 emissions from 4,271,328 propane cylinders used for home barbecues 

CO2 emissions from burning 535 railcars’ worth of coal 

Annual CO2 emissions of 0.027 coal fired power plants 

The Project is an effort of Rockford Solar Partners, LLC, a joint venture between Wanxiang America, the U.S. subsidiary of one of the largest non-state owned companies in China with $8 billion in revenues worldwide, and Chicago-based renewable energy developer, New Generation Power to develop and operate an up to 62 MW photovoltaic solar generation facility in Rockford, Illinois.

“The state’s investment will help ensure Illinois remains a leader in renewable energy development, while continuing to build on the state’s energy independence goals,” said Governor Quinn. “With partnerships with companies like Wanxiang and New Generation Power, we’re creating hundreds of sustainable, green-collar jobs and providing an economic boost to the entire state.”

Illinois Governor Pat Quinn with Pin Ni, President of Wanxiang America and Dr. Chirinjeev Kathuria, President of New Generation Power

Earlier that day, Governor Quinn has signed House Bill 6202 into law, which establishes interim solar targets to help Illinois successfully scale up to reach the state’s solar renewable portfolio standard of 6% by 2015. The new law marks a landmark achievement for solar energy in Illinois and will create over 5,000 solar panel installation, manufacturing, and maintenance jobs and significantly reduce Illinois’ carbon footprint.

Illinois Governor Pat Quinn announces Solar Ramp-Up Law and $4 million federal grant awarded to our 62MW Rockford Solar Project

“We thank Wanxiang for their investment in its North American solar panel manufacturing facility,” said City of Rockford Mayor Larry Morrissey. “We are equally enthusiastic about New Generation Power’s potential Solar Farm at Chicago Rockford International Airport. Investments in green technology such as these will help reinvent Rockford’s economy.”

“Thank you to Wanxiang and New Generation Power for its investment in our region. This is the perfect example of how the city and county came together to create jobs and promote the renewable energy industry. Currently we have locally made Wanxiang solar panels, purchased by Winnebago County, producing energy at Freedom Field,” said Winnebago County Board Chairman Scott Christiansen.

The Rockford Solar Project not only creates jobs in construction, installation and servicing but also countless additional jobs are generated in the sale and marketing of green power. The Project will also source PV solar panels locally from the Wanxiang solar panel plant.

“We are helping to establish Illinois as one of the largest producers of solar energy in the country and generating much-needed jobs for the Rockford area” said Dr. Chirinjeev Kathuria, President of New Generation Power.

Production has already started on Wanxiang’s solar panels in the flagship manufacturing facility located in the Rockford Global Trade Park adjacent to the Rockford International Airport. Rockford officials have indicated the facility is designed for expansion on the 10-acre Wanxiang campus.

“Solar energy is becoming more and more popular in America, and in the world as well. We believe the market is poised for rapid growth,” said Pin Ni, President of Wanxiang America. “We appreciate the State and City governments to support the solar business. Our goal is to expand the plant threefold to meet the demand of Illinois’s new solar energy mandate.”

In March 2010, the Illinois Department of Commerce and Economic Opportunity (DCEO) awarded a grant of $4,025,000 to Rockford Solar Partners, equivalent to 1.26% of the Project’s total cost. 68% will be financed by nongovernmental sources. The federal funding was awarded pursuant to the American Recovery and Reinvestment Act (ARRA) Community Renewable Energy Program to create and retain jobs.

ILLINOIS SOLAR RAMP-UP LAW

House Bill 6202, the Solar Ramp-Up Bill, passed the Illinois General Assembly on May 27, 2010 and established interim solar targets to help Illinois successfully scale up the solar portion of Illinois’ Renewable Portfolio Standard: 0.5% in 2012, 1.5% in 2013, 3% in 2014 to reach 6% in 2015.

WANXIANG AMERICA

Wanxiang America Corporation, headquartered in Elgin, IL, is the U.S. subsidiary of Wanxiang Group Companies, one of the largest companies in China with $8 billion in revenues. Wanxiang currently has 4,100 employees in the U.S. and over 45,000 worldwide. Wanxiang Solar is a major player in renewable energy production, including wind and solar, and is the largest manufacturer of medium/large size silicon ingot and wafer cutting in China. http://www.wanxiang.com/

NEW GENERATION POWER

New Generation Power is a renewable energy company that develops and manages projects across the USA. Headquartered in Chicago, New Generation Power was founded by renewable energy experts and experienced entrepreneurs to expand clean energy generation in the United States and increase access to alternative power in response to the growing need for green energy solutions. Committed to meeting our country’s energy needs, New Generation Power supplies affordable green energy to commercial, utility and REIT customers with an abiding sense of our environmental responsibility for future generations. http://www.newgenerationpower.org/

New Generation Power

How solar panels are made

The sun is able to produce electricity. Solar electric panels are made of photovoltaics cells--PV for short. PV stands for photo (light) and voltaic (electricity). PV technology enables to create electricity using sunlight. 

This great video shows how solar panels are made.

How Wind Turbines Work?

Wind turbines and windmills uses wind energy to produce electricity. They are mounted on a high tower--100 feet (30 meters) or more, to to have a good exposure to the wind and to harvest the bulk of energy. At height they can benefit from the faster and less turbulent wind. 

The heart of a wind turbine is the rotor. The rotor is aligned into the wind by the tail manually or via a computer-controlled tail-fan tail.

Source U.S. Department of Energy at http://www1.eere.energy.gov/windandhydro/wind_how.html

The wind's energy is captured with the blades, that look like propellers, but narrow. Typically there are 2 or 3 blades mounted on a shaft to form a rotor. A blade acts almost like an airplane wing. Wind is caused by differences in pressure. When the wind blows on a blade a low-pressure air forms a pocket on the downwind side of the blade. Since the wind always blow from high to low pressure, air from downwind side of the blade rush in to equal the air pressure. The blade is pulled toward the low pressure starting the rotor to turn. The process is called a lift. The lift force is much stronger than the wind force acting on the front side of the blade, called the drag that exerts a force which increases as the square of the wind velocity.

The combination of lift and drag causes the rotor to spin like a propeller and then the spinning of the turbine’s shaft. The rotary force produced by the turning shaft subsequently drives an electrical generator that converts the force into electricity.

Blades, like wings of an airplane, are called airfoils, because with their curved surfaces their shapes--designed to give the most favorable ratio of lift to drag, are very efficient in converting the wind energy into rotational energy. In wind turbine design, the objective is to have a high lift-to-drag ratio. This is accomplished by twisting the blades. The blades are twisted so that the wind hits them at the correct angle of attack. This twist is known a pitch.

The blades rotate at 10-22 revolutions per minute. At 22 rotations per minute the tip speed exceeds 300 ft per second. A gear box is commonly used to step up the speed of the generator, although designs may also use direct drive of an annular generator. Some models operate at constant speed, but more energy can be collected by variable-speed turbines which use a solid-state power converter to interface to the transmission system. All turbines are equipped with shut-down features to avoid damage at high wind speeds. Tip speeds of over 200 miles per hour (320 km/h), high efficiency, and low torque ripple contribute to good reliability. The ratio between the speed of the wind and the speed of the blade tips is called tip speed ratio. High efficiency 3-blade-turbines have tip speed/wind speed ratios of 6 to 7.

According to the Albert Betz' law and the hypothetical ideal wind-energy extraction machine, no more than 16/27 (59.3%) of the kinetic energy of the wind can be captured. Modern turbines may reach 70 to 80% of this theoretical limit.

Wind turbines come in various sizes. Normally for the commercial production the rotor diameters range from 130 to 300 ft (40 to 90 meters). Offshore turbine have larger rotors up to 370 ft (110 meter) diameter. Small wind turbines intended for residential or small business have rotor diameters of 27 ft (8 meters) or less and would be mounted on towers of 130 ft (40 meters) in height or less. The blade length range from 65 to 130 ft (20 to 40 meters) or more. Tower heights for horizontal-axis wind turbines (HAWT), as the balance of costs versus efficiency, are approximately 2 to 3 times the blade length and range from 200 to 300 ft (60 to 90 meters). 

The towers are mostly tubular and made of steel. The blades are made of fiberglass-reinforced polyester or wood-epoxy. The blades are usually colored light gray to blend in with the clouds.

There are 2 types of wind towers: floating towers and land-based towers. Floating towers are mounted on a floating structure that allows the turbine to generate electricity on the water. The electricity generated is sent to shore through undersea cables. The initial capital cost of floating turbines is competitive with bottom-mounted, near-shore wind turbines while the rate of energy generation is higher out in the sea as the wind flow is often stronger, steadier and unobstructed by topographic features.

Source http://www.windaction.org/pictures/2942

The output of a wind turbine depends on the turbine's size and the wind's speed through the rotor. Wind turbines  now have power ratings ranging from 250 watts to 5 megawatts (MW). Utility-scale turbines come typically in the range of 700 kW to 2.5 MW. As of 2010 the most powerful turbine is rated at 7 MW.

Wind turbines can be used as stand-alone, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. 

Utility-scale (megawatt-sized) turbines are usually installed in groups called windfarms. Several electricity providers today use wind plants to supply power to their customers. Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines to cut their electric bills. Small wind systems have potential as distributed energy resources. It refers to variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system.

An average U.S. household uses about 10,655 kilowatt-hours (kWh) of electricity each year. 1MW wind energy can generate from 2.4 to more than 3 million kWh annually. Therefore, a megawatt of wind generates about as much electricity as 225 to 300 households use. Wind energy cannot be, however, the only power source, since the wind does not blow all the time. The other energy sources are required. No power plant is 100% reliable.

Wind turbines produce some noise. The turbine blades produce a whooshing sound as they hit turbulence in the air, but most of this noise tends to be masked by the background noise of the blowing wind. An operating modern wind farm at a distance of 750 feet - 1000 feet is no more noisy than a kitchen refrigerator.

At the end of 2009, worldwide nominal capacity of wind-powered generators was 159.2 GW. Energy production was 340 TWh, which is about 2% of worldwide electricity usage; and is growing rapidly, having doubled in the past few years. 

Inside a Wind Turbine

Wind energy basics

While fossil fuels continue to diminish and negatively effect out environment, as their burning process produces around 21.3 billion tones of carbon dioxide per year, scientists around the world are searching for new and more efficient methods of generating energy.

Wind energy is an attractive alternative to fossil fuels. It's plentiful, clean, renewable, widely distributed, and produces no greenhouse gas emissions. Wind power is produced by harnessing the kinetic energy of wind and converting it into a useful form of energy by 

- wind turbines to make electricity, 

- wind mills for mechanical power, 

- wind pumps for pumping water and drainage, or 

- sails to propel ships.

Wind power don't consume fuel and don't produce pollution, such as carbon dioxide, sulfur dioxide, mercury or particulates, including aerosols, during normal operation, but still may be hazardous to the environment. Wind farms have an impact on wildlife. The main complaint against the wind turbines is danger to birds and bats. They may be injured by direct impact with turbine blades, towers, or transmission lines. Bats may also be killed when suddenly passing through a low air pressure region surrounding the turbine blade tips. Even so the number of birds killed by wind turbines is insignificant compared to the number that die as a result of exploitation of fossil fuels or other human activities. More research is needed in relation to the bats. The construction of wind farms is not commonly appreciated also due to their visual effects.

Wind power is non-dispatchable, that means that all of the available output must be taken when it's available. It's becoming more popular worldwide as a large scale energy source, although it still provides only less than 1% of global energy consumption. 

How PV cells produce electricity

Solar electric panels made of cells PV cells generate electricity from sunlight.

Watch this video to see how photovoltaic (solar) cells transform light energy into electrical energy.

How Solar Energy Panels Work

Solar electric panels are made of photovoltaics cells--PV for short. PV technology enables to create electricity using light. The light that hits the panel is converted into clean electricity.

Solar cells produce direct current electricity from light, which can be used to power equipment or to recharge a battery. Solar panels convert sunlight into direct current (DC) electric power. DC power is then converted by inverter into alternating current (AC), to be compatible with power appliances and synchronized with utility power whenever the electrical grid is distributing electricity.

The amount of electricity consumed from the grid is measured by the utility meter. It also measures the amount of electricity we put back in the grid, depending on the direction of the flow of electricity. If more electricity is generated than consumed then the utility meter actually spins backward, sending unused power back to the electric supplier for credit.

Utility Power is automatically provided at night and also during the day when the demand exceeds the solar production.

PV technology generates electricity directly from electrons freed by the interaction of sunlight with a solar panel made of semiconductor material. The basic building block is known as a cell. PV cells have at least 2 layers of semiconductor, one is positively charged and one negatively. When the light shines on the semiconductor the electric field across the junction between these 2 layers causes electricity to flow. The greater intensity of light the greater the electricity. There are no moving parts, so this is a silent operation. Many cells put together are known as a module, and many modules assembled together form an array. A single module is enough to power an emergency telephone, but for a house or a power plant the modules must be arranged in multiples as arrays. PV system consists of an array of modules generating DC electricity, an inverter, and sometimes battery storage back up with charge controller.

The amount of electricity available depends on the geographic location. The amount of electricity generated is proportional to the number of panels and the type/efficiency of the panels. In California the average residential customer purchases 6,500 kWh per year. Economically the optimal solar system size is usually between 50% - 75% of the annual household needs. Typical residential solar PV systems range in size of 50 - 600 square feet. A system composed of the highest efficiency monocrystalline cells will produce 1kW per hour for every 60 square feet. Less efficient polycrystalline cells will require 90 - 130 square feet, while thin-film systems need the largest area, up to 300 square feet to generate 1 kW.

A significant market has emerged in off-grid locations for solar-power-charged storage-battery based solutions. There is a market for off-grid power for remote dwellings, boats, recreational vehicles, electric cars, roadside emergency telephones, remote sensing, and cathodic protection of pipelines.

What is solar radiation?

Solar energy is created at the core of the sun by nuclear fusion, where millions of tons of hydrogen are converted into helium. The process generates enormous heat that causes atoms to discharge photons. Then photons are being absorbed by gas molecules, causing nearby atoms to re-emit other photons. After countless repetitions the photon finally reaches the sun’s surface. The last 20% of the journey to the surface of the Earth the energy is transported mostly by convection. It takes a photon approximately 100,000 years and circa 10²⁵ absorptions, and re-emissions to travel from the sun’s core to the surface. To reach the Earth sun’s ray takes about 8 minutes.

Cutaway - The three major zones of the Sun's internal structure. The core (temperature of 15 million degrees). In the large radiative zone the plasma and energy are gradually moved outwards from the core over a period of thousands of years. Finally, the hot plasma is cycled through a convection process (represented by the series of circles) in the convection zone up to the surface and out into space. SOHO

Outside the Earth at the average earth-sun distance at the top of the atmosphere, solar radiation is calculated to has an intensity of circa 1367 W/m², defined as the Solar Constant, but only about 40% of the solar energy caught at the top of Earth's atmosphere passes through to the surface. Still this amount of energy is thousands times more than all energy generated on the Earth.

Solar radiation is the range of all possible frequencies of electromagnetic radiation emitted by the sun. Infrared radiation (IR) emitted by the Earth's surface and its atmosphere is called terrestrial radiation. Components of solar and terrestrial radiation and their approximate wavelength ranges are as follows:

Ultraviolet: 0.20 - 0.39 µm

• 0.20-0.29 µm (UVC), 
• 0.29-0.32 µm (UVB), 
• 0.32-0.39 µm (UVA).

Visible: 0.39 - 0.76 µm

Infrared: 0.76 - 100.00 µm (near-infrared: 0.76 - 4.00 µm)

The electromagnetic spectrum (specific distribution of electromagnetic radiation emitted or absorbed by the object) extends from below frequencies used for radio to gamma radiation, covering wavelengths from thousands of miles down to a portion of the size of an atom. Picture by Inductiveload.

Gamma rays, X-rays, and ultraviolet radiation < 0.20 µm are selectively absorbed in the atmosphere by oxygen and nitrogen and turned into heat energy.

The sun emits 7% of ultraviolet radiation in the range of 0.20 - 0.39 µm. UVC is absorbed by the concentration of ozone (O₃) gas in the stratosphere, while UVB and UVA can be responsible for sunburn.

The colors within the visible light are violet, blue, green, yellow, orange, and red. Visible light stimulates the perception of color, and regulates the timing of animal activities such as migration, or photosynthesis of plants. In this zone the sun emits nearly 44% of its radiation.

Infrared solar radiation is emited in 49% by the sun. Almost 37% is radiated between 0.76 and 1.5 µm (near IR) and only 12% at far IR. Infrared solar radiation with wavelengths greater than 700 nm is partially absorbed by carbon dioxide, ozone, and water present in the atmosphere in liquid and vapour forms. Roughly 30% of the sun's visible radiation (wavelengths from 400 nm to 700 nm) is reflected back to space by the atmosphere or the Earth's surface. 

Nearly 99% of solar, or short-wave radiation is in the range of 0.3 - 3.0 µm and the bulk of terrestrial, or long-wave radiation in 3.5 - 50 µm.

Every location on Earth receives sunlight at least part of the year, but the  amount of solar radiation varies and depends on geographic location (including latitude and elevation), time of day, season, landscape, and weather, such as cloud cover.

Since the Earth is round, the sun strikes the surface at different angles ranging from 0º (just above the horizon) to 90º (directly overhead and gets all the energy possible). The more inclined the sun's rays are, the longer they travel through the atmosphere, the more scattered and diffuse. Polar regions never get a high sun.

The total quantity of energy emitted from the sun's surface is approximately 63,000,000 W/m². As solar radiation passes through the atmosphere some of it is absorbed, some diffused, and some reflected by gas molecules and suspended particles. The solar radiation that reaches the Earth's surface without being scattered is called direct beam solar radiation. Atmospheric conditions can reduce direct beam radiation from 10% on clear, dry days to 100% during cloudy days.

Direct sunlight has a luminous effectiveness of about 93 lumens per watt of radiant flux and if not blocked by clouds, is experienced as sunshine. Bright sunlight provides illuminance of approximately 100,000 lux or lumens per square meter at the Earth's surface.

Almost all of the energy that drives the various systems (climate systems, ecosystems, hydrologic systems, etc.) found on the Earth originates from the sun. The interest of solar energy is continuously growing, and professionals recognize it’s immense energetic perspectives. 

From sustainable point of view solar energy is the most attractive from all of the renewables. Solar power is free and clean. There is no side effects from obtaining it, no harmful emissions, no natural resources reduction, no waste production, and installation of the solar systems, in most cases on architectural structures, do not affect the scenery.

We can capture and convert solar radiation into useful forms of energy, such as heat and electricity, using a variety of technologies. The technical feasibility and economical operation of these technologies at a specific location depends on the available solar radiation or solar resource.