Renewable Energy 2 – Solar Power  

In reality, nearly all energy on the planet is derived from solar radiation – You know, from that big fusion generator in the day sky, e.g. photosynthesis and wind currents from differential solar heating of the atmosphere and terrestrial surfaces (water, land and ice).  Energy can also be obtained from the planet’s volcanic activity, but while viable and used in some areas Is not a major source for the near future for most of the planet (this latter option will be discussed under geothermal in a later post).

The energy from the sun powers life on Earth and especially photosynthesis that allows life to exist (and a little chemosynthesis).  The potential for humans to capture this energy is immense – consider that each single day on Earth, enough sunlight is received to power human consumption for 27 years at current levels of usage.   Imagine being able to capture it all.  Obviously, we can’t capture it all with current technology, and we really don’t need to, because the sun shines every day, even when it is cloudy and the seasons make the days longer and shorter during the year.  Obviously, some places are better than others to capture sunlight and it goes without saying – yet I feel I need to admit it for those that insist on bringing up the limitation – that its use is limited to daylight hours.

Solar technology is not new. Indeed, people have been utilizing passive solar for thousands of years – Architectural Design uses exposure direction, windows, building materials, eaves and canopies in buildings to maximize capture of sunlight in winter; thermal mass materials that absorb, store, and release heat.  Yet, passive solar design keeps buildings cool in summer through window placement, absorbent materials, air flow, and sun shields to block the sun.  Passive energy is extremely cost effective since it requires no energy to use.  Active solar, as the name suggests, uses the sun in some technological way to focus, move, or store solar energy in some form.  Solar thermal Panels use dark, heat-absorbing metal plates, or heat absorbing solutions in tubes, within in glass-covered boxes, often mounted on roofs for maximum exposure.  Even on a cloudy day, thermal works since it is the ambient temperature that often heats the collection system, although direct sun does make it faster and more efficient.  Visit Scotland or northern Germany and you will see lots of solar thermal heating panels – countries not noted for their long sunny days, especially in winter when the panels still work well.  They use this to warm air within the house, but more often as solar water heaters.  Historically, the first thermal solar collectors were built in 1767 and the first commercial solar water heaters in 1890, so solar has been with us a long time already.

What we typically think about solar energy, we are thinking about active solar using Photovoltaic cells (PVs) that convert solar energy directly into electrical energy.  PV cells work by making use of the photoelectric effect: That is, when sunlight strikes a charged metal plate, the excited electrons migrate through a one-way membrane to another plate.  Like all electricity, electric current is produced by the movement of electrons, and in PVs, the electrons are forced to move along a wire to return to their original source.  One typical kind of PV is when light strikes negatively charged phosphorus, and electrons move from the phosphorus side of the silicon plate to the boron side, creating electric current.  A solar panel is a whole array of these small solar cells.  Since the individual PV cells are so small they can be built to any size ands scale.  You don’t have to cover a roof in Solar PV panels, you can use solar shingles – a form of building-integrated photovoltaics.  These solar roof shingles look like and function as conventional roofing materials, such as asphalt shingles or slate, but producing electricity as well as roof cover.  Commercially, California has been using a solar furnace by having 352,000 mirrors focus heat from the sun onto three water boilers mounted on a tower.  Water in these boilers is turned into steam that then turns turbines to generate electricity.

The biggest advantage of solar is that you don’t need an army to protect or acquire your resource.  It is totally local, and it is also very portable.  Backpackers can carry a small flexible roll-up panel that they can hang from a tree branch to charge small electronic devices they bring in to the wilderness.  In places like Nepal, locals carry fold out solar mirrors, which focus the sunlight onto a central spot to cook or heat a kettle of water.  In many remote rural villages and refugee camps around the world, locals use simple box solar ovens to cook their family meals.  In 2016, a European company used a solar PV powered set of electric motors to power a plane to fly around the world (even covering the long hop from Japan to Hawaii in one flight) at a top speed of 87 mph.  The solar technology for extended options is still in its infancy, but the potential for larger scale use is just waiting for R&D to make some strides forward.  The only drawback of Solar (besides needing sunlight to work) is that the technology has to be manufactured – hence mining, smelting and energy needed for active solar technology manufacture is still a requirement; however, a life-span of 25-35 years means the amount of front end costs (resource needs) is greatly minimized compared to current extraction energy technologies (i.e. Fossil Fuels).  At this time, the cost for solar is competitive to fossil fuels even without subsidies.

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