At the heart of all our products is the paired rotor technology developed by Epicam. The rotors form a rotary displacement device. This is more efficient and scalable than a turbine, which harnesses energy from flow over its blades, and has fewer losses to friction than a reciprocating displacement engine with a piston.
The unique geometry of the paired rotors, one with lobes and a second with pockets, is protected by 6 worldwide patents.
The rotor pairs create multiple expanding or contracting chambers as they turn, with a complete pocket expansion or contraction occurring in only 90 o of rotation. The rotors are designed to spin at 10,000-20,000 rpm, with up to three cycles per rotation, allowing high throughout.
With very high compression/expansion ratios over very short times and distances, and machined to a high tolerance, the rotors do not touch and are therefore almost frictionless without any lubrication.
All of this results in gas compression or expansion with the following characteristics:
Very low friction
High power density
High compression/expansion ratio
Cryofuel Energy Systems is a company set up to exploit the paired rotor technology patented by Epicam, in all applications relating to methane. CES has a worldwide exclusive license to the technology for these applications.
We believe methane is a versatile and efficient energy carrier. Our products allow efficient production and use of methane in off-grid locations and at small scale.
We see the transition to a fully renewable gas grid as essential in the long term, and our products as a key enabler in that transition.
Virtual pipelines’ are increasingly used to transport either natural gas or biomethane from production site to the point of use. Typically the gas is compressed to 250 bar, loaded onto trucks, and then depressurised after transport for grid injection or use in CHP.
Significant energy is used to compress the gas to 250 bar, and given the high
pressure gradient, it should be possible to recover some of that energy when
that pressure is dropped again. However, due to the cooling effect of depressurisation (the ‘Joules Thompson effect’), currently available depressurisation units require energy input to stop the equipment freezing. (At large scales, turbines are used to recover some energy, but these are too inefficient to work at the scale of virtual pipelines.)
Cryofuel Energy Systems uses paired rotors to harvest energy from the flow of gas from high to low pressure. Some of this is used to heat the equipment, but a significant excess of energy is left over in the form of useful electrical energy. We are developing systems to handle varying throughputs of gas, from 250 scm/hr to 2,000 scm/hr, with the first of these commercially available from 2019.
Increasingly LNG is being recognised as a more economic alternative to LPG for off-grid gas applications. At the point of use, the LNG is passed through a heat exchanger to regassify it and bring it back to close to ambient temperature for use.
Significant energy is used to liquefy gas to LNG in the first instance, and the cryogenic state of the gas represents a usable energy store which is currently wasted in small scale applications.
Cryofuel Energy Systems is developing a unique small scale LNG vapouriser which generates energy from the expansion of LNG when it makes the transition from liquid to gas. First the LNG is passed through a heat exchanger causing it to warm significantly, but under restricted flow conditions, resulting in a high pressure supercritical gas. This is then allowed to expand through paired rotors to harvest energy from the flow of gas from high to low pressure.
Small scale liquefaction plants (2-25 tonnes/day) offer many advantages for the efficient distribution of small scale sources of natural gas and methane.
However, plants in this capacity range lack the efficiencies of scale achievable in large scale liquefaction trains, and are thus unattractive on grounds of both energy and operating cost.
Cryofuel Energy Systems is in the early stages of combining paired rotor technology with other best-in- class small scale liquefaction technologies. The patented rotors offer the capability to compress gas efficiently without the lubricants and filters needed with conventional screw compressors, and then to expand or ‘flash’ the gas in a final step while recovering energy for the rest of the process.
While most biogas upgrade plants make use of water scrubbing or membrane technology, one other approach is cryogenic upgrade. Biogas is cooled in three stages, the first to freeze out water, the second to freeze out carbon dioxide and the third to liquefy the remaining methane. This is most advantageous if the biogas source is remote from the gas grid, as the product, liquid methane, is easily transported (while the alternative, compression, would require additional equipment).
Cryofuel Energy Systems is in the early stages of combining its approach to small scale methane liquefaction with the developers of cryogenic biogas upgrading. The result will be the most efficient and cost effective biogas upgrade system on the market, for grid-remote biogas producers, or biogas producers interested in supplying liquid biomethane for the heavy duty transport fuel market.