Cracking an oil supply

A US company has discovered a way of processing ultra-thick oil buried in tar sands to make a product that could supply worldwide industries. Siobhan Wagner reports.

Useful oil is becoming increasingly hard to find. As global reserves deplete, producers are looking to other, previously untouchable sources, such as tar sands, to refine into petroleum products.

In the tar sands of Alberta, Canada alone, there is an estimated 2.5 trillion barrels of ultra-thick oil. The bitumen in these sands is neither oil nor tar but a semi-solid, degraded form of oil that does not flow at normal temperatures and pressures, making it difficult to extract.

An American technology company, however, has developed a way to transform these ultra-thick oils into oils, gasoline and other petroleum products thin enough to pump through a pipeline.

The technology developed by PetroBeam is called cold cracking, which uses beams of high-energy electrons to transform the molecular structure of ultra-thick oil. This promises to be less expensive and more energy-efficient than traditional refining methods that involve intense heat and pressure, which breaks some chemical bonds, making the oil less viscous. The cold cracking approach cracks the heavy oil with standard industrial irradiation equipment at room temperature and atmospheric pressure.

Cold cracking is sometimes confused with a radioactive process but Walter Chappas, a nuclear engineer and co-founder of PetroBeam, said: ‘There are no radioactive materials involved with cold cracking. What we’re using is electrons, or you could even say electricity, right out of the electrical lines. We have a transformer, which takes those electrons coming out of the wall socket and increases their voltage from, in the US about 120V, or about 220V in Europe, to 1MV or 5MV. We then spray that electricity on to our product. In the oil, these electrons cause many of the same chemical changes that you would get from gamma rays or X-rays.’

PetroBeam has been researching the use of cold cracking for the oil industry for 15 years. One problem the engineers faced was the oil’s malformed molecular structure after irradiation. Oil molecules are mostly made of long chains of hydrocarbons. Generally, the longer the chain, the higher the viscosity and the less valuable oil becomes.

When a high-speed electron hits a hydrocarbon chain it sometimes breaks in two but more often, the chain will bond to a neighbouring chain in a process called cross-linking. Then the sticky molecules will transform into a mess of interconnected chains. That outcome is necessary for applications such as heat-shrinkable bags but not for energy-producing purposes.

Early in 2005 PetroBeam, with partners in Kazakhstan, found a way to crack the crosslink bonds (and keep them cracked) without extra heat and pressure. The method is a secret but the company says it required no adjustments to its irradiation equipment.

Now it must demonstrate that the technology creates a product with long-term stability. ‘We’ve done a lot of stability tests, and we’re pretty confident this is not a problem but there are many kind of technologies where you treat it one day and then the next day it goes back to where it started from or perhaps even a bit worse,’ said Chappas.

Engineers are testing small amounts of oil using electron guns. They are in talks with ‘several large oil companies’ but Chappas said the technology must first demonstrate it meets ‘the scale-up test’. PetroBeam is operating out of a small private plant in Alabama, US but is now constructing a 1,000-barrel-per-day pilot plant that should be finished by mid-year.

Chappas admits developing a technology that meets the needs of the worldwide oil industry will not be easy. ‘When we talk about scale-up, very few people have experience of taking a process that can work on a gramme to 100,000 barrels a day,’ he said. ‘It’s mind-boggling how much that really is.’