Isobarix: Unlocking constant-pressure gas storage
Lead Participant:
CHEESECAKE ENERGY LIMITED
Abstract
Those familiar with TV weather forecasts will likely have heard the term "Isobar", which is a contour of constant pressure.
Isobarix is all about storing energy gases in tanks at constant pressure irrespective of how full/empty the tank is. The gases of most interest in this project are (i) compressed air, (ii) pressurised hydrogen and (iii) compressed natural gas (CNG).
On weather maps, pressures vary by only a few tens of milli-bars between lowest and highest pressure points (<1% of 1bar). Hydrogen is typically stored at 700 bar (~700 times atmospheric pressure) and CNG is typically stored at 250 bar -- as is compressed air for energy storage purposes. The physical properties of the gas determine the optimal storage pressure in terms of carrying the greatest amount of energy for the lowest mass of tank - and correspondingly the lowest cost.
Storing gas at constant pressure has multiple advantages: (i) the compression/expansion machinery always operates at the same conditions so that performance can be optimised specifically for that one operating point, (ii) all of the gas present at full charge can be extracted, rather than having to stop withdrawing gas when the pressure in the tank gets too low, (iii) stresses in the tank walls do not cycle up and down, consuming fatigue life of the tank, (iv) it is not necessary for heat to flow through the tank walls in order to keep gas temperature constant and (v) the same hardware used for isobaric gas storage can serve directly to perform over-pressure tests at no additional cost.
Cheesecake Energy Ltd (CEL) is focused on developing energy storage systems especially suited to supporting electric vehicle charging stations and enabling high penetrations of solar power. Although two-thirds of the electricity is stored in the form of heat, these systems rely on storing pressurised air at constant pressure to hold the remaining third. These air stores are the single largest system cost.
If CEL can determine a full solution to the problems associated with isobaric storage, it will not only have found a major cost reduction for its energy storage systems but will also have solved problems for the emerging hydrogen economy and also for the CNG industry for refuelling low-emissions freight transport over the coming decade.
Isobarix is all about storing energy gases in tanks at constant pressure irrespective of how full/empty the tank is. The gases of most interest in this project are (i) compressed air, (ii) pressurised hydrogen and (iii) compressed natural gas (CNG).
On weather maps, pressures vary by only a few tens of milli-bars between lowest and highest pressure points (<1% of 1bar). Hydrogen is typically stored at 700 bar (~700 times atmospheric pressure) and CNG is typically stored at 250 bar -- as is compressed air for energy storage purposes. The physical properties of the gas determine the optimal storage pressure in terms of carrying the greatest amount of energy for the lowest mass of tank - and correspondingly the lowest cost.
Storing gas at constant pressure has multiple advantages: (i) the compression/expansion machinery always operates at the same conditions so that performance can be optimised specifically for that one operating point, (ii) all of the gas present at full charge can be extracted, rather than having to stop withdrawing gas when the pressure in the tank gets too low, (iii) stresses in the tank walls do not cycle up and down, consuming fatigue life of the tank, (iv) it is not necessary for heat to flow through the tank walls in order to keep gas temperature constant and (v) the same hardware used for isobaric gas storage can serve directly to perform over-pressure tests at no additional cost.
Cheesecake Energy Ltd (CEL) is focused on developing energy storage systems especially suited to supporting electric vehicle charging stations and enabling high penetrations of solar power. Although two-thirds of the electricity is stored in the form of heat, these systems rely on storing pressurised air at constant pressure to hold the remaining third. These air stores are the single largest system cost.
If CEL can determine a full solution to the problems associated with isobaric storage, it will not only have found a major cost reduction for its energy storage systems but will also have solved problems for the emerging hydrogen economy and also for the CNG industry for refuelling low-emissions freight transport over the coming decade.
Lead Participant | Project Cost | Grant Offer |
|---|---|---|
| CHEESECAKE ENERGY LIMITED | £355,631 | £ 248,942 |
Participant |
||
| INNOVATE UK |
People |
ORCID iD |
| Michael Simpson (Project Manager) |