Peter Kearl, an engineer who once worked at Oak Ridge National Laboratory in Tennessee, believes that microwaves may be the answer to our energy worries. It is an ongoing global debate as to whether fracking for gas and oil is a godsend or an environmental nightmare. However, Kearl believes that by zapping the ground with microwaves, we may be able to achieve a cleaner way of retrieving those valuable fuels. It could be a tough sell though, as he admits, “We’re still trying to convince people that this is not something out of Star Wars”.
The idea behind this technology can probably be replicated in your kitchen. Imagine putting your cold mug of tea in your microwave oven. The mug itself doesn’t heat up, however the water in your tea does. The plan is to replicate this tea effect, only 6,000 and 10,000 feet under the ground. When the emitter is lowered down the well, it will heat up all the trapped water, but the rocks will remain unaffected by the microwave’s rays. The boiling water will liquefy the surrounding solid hydrocarbons and the water will then become steam, hopefully allowing everything to flow through the cleared pores and collect at the surface. The effect produced will be very similar to fracking, but it avoids the use of harmful chemicals and avoids contaminating water. As well as this, the use of steam ensures the oxygen does not become easily flammable and will help to avoid underground fires.
There is some worry of the potential damage to microorganisms but, despite this, big companies such as ConocoPhillips and BP are warming to the concept as it provides a cheap alternative to previous fracking and has the potential to bridge the energy gap until renewable sources truly take off. Also, it could store carbon, keeping us from destroying pristine areas and even generate water clean enough to drink. Microwaves can exploit an under-appreciated feature of most hydrocarbons: although they can be a solid, like tarmac derived from bitumen, at room temperature with just a little heat, long chain hydrocarbons can easily become considerably less viscous liquids. This frees the pores, so allowing the oil or trapped gas to be released.
This could not be more dissimilar to fracking as it stands. Fracking is a violent and corrosive way of retrieving these fuels, but only because it has to be. The technique, formerly called hydraulic fracturing, involves injecting the ground with water and chemicals, collectively known as fracking fluid. This, combined with horizontal drilling, has drastically transformed the geology where fracking occurs and the release of greenhouse gases from poorly sealed wells has a huge environmental impact.
Yet this is not a new idea. In fact, the idea of using a microwave antenna has been around for a while, but the equipment required to produce, guide and stabilise the high power beam was far too bulky to be lowered down the narrow wells. But the technology is now almost ready, and there are lots of emerging designs which will make this technology cheap and accessible, including the one Kearl set up for use by the defence industry. Naturally, Kearl believes his technology could be used for more than just harvesting oil from new wells. He believes that, if correctly applied, it could be used to unblock existing wells which have become too sluggish to be worth operating. Hence the financial and environmental advantages of this cannot be underestimated.
Still, despite all the good theory behind using microwaves to zap stubborn oil and gas deposits out of the ground, the technique is yet to be employed on a full-sized deposit. Extensive small scale lab experiments, despite proving very positive and being a step in the right direction, are a long way from the real thing. Also, so far a complex mix of chemical agents has been required to get the hydrocarbons to flow over such a vast distance. Kearl insists, however, that the the technique will scale up. However, for now, the beam only has a range of around 25 meters. But the far larger hurdle which has been left untouched is the energy usage of the technique. In principle, microwave zapping “uses less energy than conventional extraction,” says John Robinson from the University of Nottingham, UK. However, the saving is lost as soon as the inefficiencies of running a microwave antenna on electrical power are factored in.
So, who knows. Maybe the future of microwaves is to provide us with a green fracking alternative. But for now, I think they are best suited to warming up my tea.
Original illustration by Euan Jarvis.