What exactly are the limits to the power of renewable energy sources, asks Ekaterina Tikhoniouk
Energy comes just a little too easily these days. We switch on the ignitions of our cars without thinking about how much oil there is left in the world. We often turn on the light switch or plug our phone charger into the wall without even wondering where all this electricity is coming from. Is it coming from renewable sources? Or are we thoughtlessly destroying the last reserves of fossil fuels that will certainly not replenish themselves anytime soon?
Most of us seem to take it for granted that these fossil fuels of oil, gas and coal will last forever, while in reality at the rate that we’re burning up fuel, it’s estimated that we would have fully depleted our planet’s oil reserves within the next 15 years and its turf and coal reserves by 2020.
Humans have been deriving energy from the things around them for millennia. Prehistoric man built fires from tree branches for warmth. Around the year 8,000 BC, man discovered coal. Farmers began cutting turf on their bogs, to burn during the winter months.
A great leap forward was made with the discovery of the steam engine at the start of the 18th century. Steam-powered trains, their furnaces fed with enormous amounts of coal allowed for great transportation networks to spring up all over the globe, which marked the beginning of the industrial revolution.
Thales of Miletus had known about electricity in 600 BC, but Otto von Guericke did not build the first static generator until 1675 AD. Electricity had very little use until the invention of the telegraph around 1840. It was quickly followed by the telephone, radio and television. Edison added lighting in 1880. Successful batteries had begun appearing in the 1840s and onwards.
But there is evidence that batteries have actually been around for much longer than previously thought.
In 1936, controversy was sparked by the discovery of the so-called ‘Baghdad Battery’ that was discovered during the excavation of the ruins of a 2,000-year-old village near Baghdad. Believed to date back to Parthian times, this particular find has been baffling archaeologists and scientists for years.
The ‘battery’ consists of a bright yellow clay urn sealed with an asphalt plug. The urn contains a sheet-copper cylinder with a narrow iron rod struck through the asphalt stopper and hanging down the centre of the copper tube. The inside of the asphalt stopper bears the undeniable marks of acid corrosion. The whole mechanism bears undeniable similarity to a modern-day battery.
Experiments with the Baghdad Battery have determined that, if filled with acid, it can generate between 1.5 and 2 volts. Although this is quite a small amount of power, there’s a possibility that many of these primitive ‘batteries’ could have been linked together to achieve higher voltages. But what was its purpose? Was this small clay urn used for electroplating (gilding a material in gold), or possibly for the treatment of pain? No one knows even now in the 21st century the ‘Baghdad Battery’ remains a mystery.
In the 2,000 years since then, our society has become completely and utterly dependent on energy and now, dwindling fossil fuel resources have forced us to come up with alternative solutions for powering our cars, buildings and factories.
The most common mainstream forms of alternative energy are wind, hydro and solar power. But traditional wind and solar sources are usually low intensity sources, with large areas of land needed to collect enough energy to power a densely populated area.
But what other options do we have? Surely, there must be more inventive and efficient ways to generate energy.
In fact, more and more bizarre but plausible energy solutions have been arising in recent years, from things such as viruses, alcohol or even man-made tornadoes. There is even the possibility of deriving energy from fruit.
Creating a battery from a lemon is a common science project for kids. A metal nail galvanised in zinc and copper penny are stuck into a large fresh lemon, creating a weak single cell battery. The nail and coin work as electrodes, while the lemon juice is the conducting electrolyte and four lemons linked together can actually create enough current to light an LED bulb for a surprising amount of time.
Potatoes, tomatoes and other fruits or vegetables that contain acids can also be used to light LED bulbs. It would take over 9,000 lemons to power a single flashlight bulb, but it’s a start.
Another bizarre source of energy are onions. Californian onion farmers Bill and Steve Gill have discovered a way to turn onion juice into fuel. An anaerobic digester converts treated onions into biogas, which is then turned into methane. This methane is pumped into a 600-kilowatt fuel cell to make electricity.
Common viruses that are harmless to humans can be harnessed to create batteries that have the same capacity and performance as typical rechargeable batteries. Researchers at MIT are currently genetically engineering viruses that build cathodes and anodes, creating prototypes the size of a coin.
Scientists in California have genetically engineered bacteria that excrete renewable petroleum when fed agricultural waste. The company LS9 claims that this new oil will be carbon negative.
Natural tornadoes contain vast amounts of energy. The average tornado contains as much energy as a typical power plant. This prompted Canadian engineer Louis Michaud to create a way of harvesting all this potential energy by creating man-made tornadoes in a controlled environment using a prototype he calls the Atmospheric Vortex Engine. He claims that with a proper facility, he could extract as much as 200 megawatts of electricity that is enough to power a small city.
Alcohol may play an important part in future energy production. In Sweden, hundreds of thousands of litres of confiscated alcohol are shipped to waste-fuel plants in Linkoping, where they are added to other waste and turned into methane. Several Scottish whiskey distilleries run their own plants on by-products of the distilling process.
Meanwhile, in countries such as Brazil and America, alcohol is being used more and more as fuel. Bioalcohols are alcohols obtained from biological sources. Bioethanol is an alcohol made by fermenting the sugar components of plants. It is made mostly from sugar and starch crops. Ethanol can be used to fuel vehicles in its pure form, as in Brazil that has an ethanol fuel programme, which means that many of its vehicles run efficiently on this biofuel, or added to gasoline in order to improve emissions.
It sounds quite bizarre, but with this rate of advancement, one day we may all live in a world where you can fill your car with beer, and plug your television into the nearest piece of fruit.