The Sun radiates 89 PetaWatts amount of energy at the Earth 24 hours a day, 365 days a year. It is enough to cover the total energy usage of the Earth 6000 times over. The key to endless energy is all around us in the form of sunlight, ripe for the taking. The ability to feasibly harness this energy would surely be the Holy Grail of all energy sources.
The Sun is of course responsible for almost all forms of energy on the earth. Wind and wave power are both driven by heating from the Sun. Fossil fuels contain energy from plants & animals that have soaked up juice from Solar rays. The same goes for Biofuels. About the only energy sources that aren’t derived from the Sun are nuclear, which harnesses atomic energy, and tidal, which harnesses the gravitational energy from the Moon.
Solar power, converting energy from sunlight directly into electricity, comes in two main forms: PhotoVoltaic & Concentrating Solar Power. I’ll explain the difference and talk through some of the considerations that need to be made when choosing one over the other.
Concentrating solar power uses arrays of mirrors to direct sunlight onto a very specific target in order to heat it up to very high temperatures. This is then used as a heat source for a conventional power station (whereby steam drives a turbine which generates electricity). It’s a very simple concept that has been around for more than a century. However, it is far from a simple technology. It requires detailed design to produce a system that is efficient as possible and the manufacture of the huge curved mirrors is quite an engineering feat.
PhotoVoltaic, on the other hand, uses a flat film of semi-conducting material. This has a special property whereby light shining on it will induce an electrical current, which can then be channelled off into the electricity grid. This method directly transforms the incoming sunlight into electricity although, as always, there is a loss.
Every solar power station varies, but in general the most efficient large scale power stations are built using Concentrating Solar arrays. It usually pips PhotoVoltaic cells in terms of energy efficiency for large arrays. However, Concentrating Solar can’t be deployed on a small scale – you need a conventional turbine driven power station that is driven by the solar heat. On the other hand the effectiveness of PhotoVoltaic solar energy is much more independent of size. You can have a 1m x 1m PhotoVoltaic panel and it will work in the same way as a 100m x 100m array. For this reason any small scale solar installation, such as those people often put on their roofs, are almost always PhotoVoltaic solar panels.
Hugely important in the development of solar energy is dealing with the irregularity of sunlight. At night time or when the sun is hidden behind clouds, the amount of solar energy available is vastly reduced. Therefore the ability to store the produced energy efficiently is extremely important. Small scale arrays often work by ‘Net Metering‘, or ‘Feed-In Tariffs‘ as they are known in Europe. The way it works is that the solar panels on your roof are connected to the energy grid. When there is excess energy to your requirements it will feed the grid and at night, when there is no solar energy, you can draw electricity back from the grid. You get paid for the energy that you supply to the grid and, depending on local legislation, its usually at a very favourable rate to encourage the uptake of solar energy.
There are various other types of solar power that are also important:
Solar Water Heaters are perhaps the simplest of all types of solar energy. The idea is simply to place a water tank/pipes in view of sunlight, usually on the roof, and then use this water for various heating functions in your house like showers and filling radiators. The most common user of Solar Water heating is Israel where it is estimated that they save over two million barrels of oil a year.
Another type of solar power is Solar Chimneys, where in effect you have a very large, thin greenhouse with a chimney in the middle. The air inside the greenhouse is heated by sunlight causing it to travel up the chimney (hot air rises, remember?). The hot air will drive a turbine in the chimney, or something similar, which can be used to generate an electrical current.
Update: Interested in Solar Panels? Check out our Win a Solar Panel Competition
The advent of 
Yes you read that correctly.
The REVA G-Whiz is currently the most popular batter powered electric car in the world. Manufactured in India, the REVA is a smart 3-door city car that will fit two adults in the front and two children in the back. A full charge will take around 6 hours and will cost less than $1.50 meaning running costs are an astounding 2c per mile. The newest version includes higher performing Lithium Ion batteries that extend the range to 75 miles.
The Th!nk City is another 3-Door Electric vehicle running on sodium or lithium batteries. A product of Norwegian firm Th!nk, the City car is available in Norway and European markets with plans to come to the US soon. It is one of only two crash tested and highway certified fully electric vehicles. (The Tesla Roadster is the other). The car is designed so that it can be recycled after it has been decommissioned helping to further reduce its environmental impact.
Available next year, the Smart ED is the first all electric vehicle from SMART, manufacturers of the pocket sized city cars that are ever more popular in Europe, and – believe me – they look even smaller in real life. The ED follows much the same design as other Smart vehicles, but behind the fuel cap is actually a standard mains plug. The Smart ED can fit only 2 passengers and will take around 8 hours to charge the batteries to capacity.
The Tesla Roadster is without doubt the cream of the crop of electric vehicles. With a stunning design and performance to rival some of the best fossil fuel powered sports cars, the Roadster is truly a break through vehicle that demonstrates that you don’t have to make cutbacks on quality if you want to go electric. It combines a 0-60 mph time of 3.7 seconds, with an efficiency that is up their with the best electric vehicles – achieving a breathtaking 120 miles per gallon equivalent (
Whilst not technically a fully electric vehicle, the Toyota Prius with its hybrid engine deserves a mention here. The greenest vehicle by the world’s largest automaker is an important milestone and a very advanced specimen of technology. The hybrid engine means the car will run on fuel but will also use advanced techniques such as regenerative breaking (which captures a vehicles kinetic energy whilst breaking) to charge an onboard battery. When the battery has sufficient power stored up, the engine can switch to EV mode, whereby it is propelled purely by electrical energy. This hybrid engine results in 54.7 mpg rating, although the 3rd generation models will bring this up to 60.3 mpg. Its no surprise to learn that worldwide sales of the Prius reached 1.2 million in early 2009.
The Lightening GT is in a similar mould to the Tesla Roadster. The British made Lightening features a sleek design and a 0-60 mph time of under 4 seconds. A killer feature is its fast charging lithium-titanate battery which, given the right high capacity power source, can charge in 10 minutes. On standard mains power this would be more like overnight. The lightning GT is a 2 seat convertible and is available to order now for 2009/2010 delivery in the UK and is set to reach the US market ’soon’.
The iMIEV from Mitsubishi Motors Company is due to start production in 2010. It can fit four full sized adults but has a greater efficiency than the G-Whiz, getting around 100 miles from 16 KWh and has an impressive top speed of around 80 mph.
The Mega City available from NICE (No Internal Combustion Engine) is a french made 2-seater city car. NICE also have a large truck version, the “Mega Mutitruck” and a pickup style version, the “Mega Worker”.
The Vectrix was the first high powered electric scooter available on the market. Its great design and 0-50 mph in 7 seconds made it very desirable. The company unfortunately went in to liquidation earlier this month and won’t be able to continue existing in its current form. However, Vextrix scooters are still readily available second hand and the technology could be given further life if a suitable company swoops in to buy the remaining assets.
The Cargo Scooter is a Dutch Made Electric Scooter that has been picked up by Domino’s Pizza to equip their fleet of delivery vehicles. Taking only 2-3 hours to charge, it is adept for traversing short distances quickly, cheaply and environmentally. It is available now in both European and North American markets.
