When you think about it, the sun is probably the biggest reason we exist and the only reason we have fuel to supply our insatiable rate of development. For one, if it wasn't for the heat of the sun, fossil fuels wouldn't have been formed. And we have been using it to our advantage in some way or the other, like drying clothes or building houses according to the sunrise to optimize the amount of light that enters our home.
We are now in an era where if we do not manage to harness this solar energy to the max, we will face severe setbacks. This leads us to three questions:
- Of the 5700ºC on the sun's surface, we get only 20ºC (the average temperature of the earth's surface). How do we intend to make the most of this?
- The sun shines only in the day. How do we make the energy last us through the night?
- With current methods, we cannot manage to harness the entire energy falling on a particular surface. How do we concentrate all this energy into one spot?
The answers to these questions lead us to think about the future of solar energy. Leaders in energy management predict that it will soon be introduced as a fully competitive energy source along with all the ones currently used. Shell predicts that 50% of the total energy intake of the earth will be from solar energy by 2040. Learn more on how they intend to do that.
Today's Solar Energy
One of the main ways to harness solar energy is photovoltaic (PV) cells. The other sources are water and air. Photovoltaic cells simply convert light to electricity, which is then supplied to wherever it's needed. Once used as the power source for satellites (as long ago as 1958), these cells are today used in the many common sources like calculators. The main setback with these cells is that they shut down if they receive little or no sunlight, which is why they can't be used at night. The other problem is concentration of light. The cell cannot manage to concentrate all the light into one spot for a strengthened effect, and instead has to rely on whatever falls on its surface. This means if we have to use PV cells, we need massive amounts of space to feed a single functional building. So you end up having huge arrays of cells, all rotating according to the angle of the sun with the earth's surface.
The final setback is due to the chemical properties of the cell. No matter how efficient a PV solar cell will be, there will always be the factor of band gap energy that restricts its total output. It is the amount of energy required to knock an electron out of its orbit, which basically is the electron that runs through the wires, what is called electricity. There are many advances in high efficiency solar panels that are trying to minimize this as much as possible (the preferable band gap energy coefficient being zero). Till recently, solar energy has been dealing with these problems.
The Future of Gathering Solar Energy
Validity of Photovoltaic Cells
They may not be perfect, but PV cells are widely used across the globe. The main reasons for this are:
- The sky high price of crude oil
- The solar panel's guarantee of being cheap to buy and lasting for at least 25 years
- Government incentive schemes, like the one in California where you get an incentive of up to $4500 for converting to a solar grid system
Also known as Solar Updraft Towers, these man-made structures are massive in size and span for miles. There is one such solar tower proposed for Arizona. To be built by the Australian company EnviroMission, the tower will be 2,625 feet tall. That's twice the size of the Empire State Building and 30 meters short of Burj Khalifa, the tallest building. It will be completed by the year 2015. The tower is said to be able to produce a peak power output of 200 MW, which is enough to supply 100,000 to 150,000 homes. What's more, the $750 million structure will need have to be maintained for at least 80 years from its first functional date, and boasts an efficiency of 60%; that's more than what most other energy sources offer. The tower works on the concept of temperature differential and so should be able to generate power even in the night.
Space-Based Solar Power
Man often shows the tendency to think far ahead of his own time. An example for this would be a space-based power plant (SBSP). The idea was thought of and has been researched on since 1970. It involves installing a satellite or a tower outside the Earth's atmosphere that can collect solar energy at a much higher efficiency than solar cells down on Earth. This bypasses all the losses incurred in gathering solar energy due to atmospheric interference and the Earth's rotation. The obvious problem in the plan is the transmission of the generated energy by the satellite to Earth. Recent studies include wireless transmission in the form of microwaves towards a receptor on the ground. This would, again, increase transmission losses. Another problem would be to successfully build a large enough satellite to generate sufficient power, but also be able to avoid all the floating space debris.
Thermal Energy From the Ocean
The temperature differential created in the ocean by the sun is another large source of untapped energy. The idea is to be able to cycle the hot water on the surface and the cold water below the surface through tubes fitted with turbines. Since this would also be based on temperature differentials, it may be just as efficient in power production in the night too.
Solar Energy in Daily Life
It is intended to integrate solar energy into almost all electrical gadgets. This includes your cell phones, laptops, home appliances and building lights. The energy harnessing devices include:
- New "plastic" solar cells
- Ultrathin dye-sensitized solar cells (said to be the most efficient)
- Carbon nanotubes embedded in the cells
The future of solar energy, for now, is all about enhancing whatever we have made so far. Technological advances can go only so far ahead. But with the present rate of fuel consumption, more and more minds are turning towards the sun as the ultimate source of energy, just like the days of old.