Until recently, carbon dioxide (CO2) emissions were a fact of life for oil and gas facilities. Whether they operate refineries, liquefied natural gas terminals or gas pro-cessing plants, companies have long claimed that pollution is unavoidable.
But advances in technology mean that oil companies now have feasible alternatives to polluting the atmosphere. With the advent of integrated gasification combined cycle (IGCC) and discharged thermal energy conversion (DTEC) technology, the environmental impact of their operations can be minimised, and there are economic benefits too.
The two technologies are based on different concepts, but have one factor in common: they can substantially reduce, if not totally eliminate, harmful emissions.
IGCC’s scientific principle is based on converting coal, high-quality coke or oil to cleaner-burning gas for power generation purposes. Essentially, the feedstock in the Middle East this is most likely to be heavy oil residues is combusted with oxygen and steam to form synthetic gas (syngas). The syngas is cleaned and then used to drive turbines to create electricity.
‘In the Middle East, most of the technology has been thermal-based because of the abundance of natural resources,’ says Joe Anis, regional executive for the US’ GE Energy, which provides IGCC technology. ‘So in terms of technology and looking at diversifying fuel sources, IGCC is a good thing to implement.’
The technology could be an attractive solution for Gulf states where gas is in limited supply. Kuwait, which is increasingly suffering the polluting effects of its oil-burning power plants, says it is actively looking at building IGCC plants, possibly to be integrated with the planned Al-Zour refinery or its other existing refineries. Saudi Arabia is also understood to be seriously considering the technology.
‘IGCC is definitely one of the preferred options,’ says Khalad al-Mushailah, acting corporate planning manager at state refinery operator Kuwait National Petroleum Company (KNPC). ‘We have studied using different types of crude as feedstock, and three different locations, and now we are looking at incorporating an IGCC plant with a refinery to complement the refining process.’
A feasibility study conducted for KNPC by the US’ Foster Wheeler recommends an IGCC power plant with capacity of up to 3,000 MW. As this would be considerably larger than any other IGCC facility in the world, KNPC is more likely to go for smaller modules of about 1,000 MW and gradually expand them.
The next step is for the pre-front-end engineering and design (FEED) to be carried out, followed by a FEED proper. Only then will a final decision be made on what looks likely to be the first implementation of the technology in the region.
Whatever the decision, IGCC will not be a quick-fix solution. The addition of a gasification plant adds 12-18 months to the normal 24-month development cycle of a conventional combined-cycle plant.
Another problem is cost. With a power generating cost of up to $3,500 a kW, IGCC can be twice as expensive as conventional generation methods, and is less reliable. Of the handful of commercially sized IGCC facilities worldwide, few have been a resounding success.
The Middle East, however, has one notable advantage: cheap feedstock. With the low cost of supplying the oil offsetting the technology, utilities may find that IGCC is as competitive as importing gas, and certainly cheaper than renewable energies such as wind and solar power.
It is this advantage that makes the technology feasible, says Al-Mushailah. ‘Each country and each example are different. It is not possible to say that one technology is particularly more expensive than another. In our case, by using IGCC, we can free up more distillate for export [which is more profitable], rather than for fuel oil for power plants, so it is economical to develop.’
An added advantage of IGCC is that it can be fully implemented with carbon capture and storage programmes to effectively negate any pollution. Unlike conventional combined-cycle plants, where the low pressure and high particulate content of flue gas makes it hard to treat, CO2 can be removed from the syngas before it is burned. Additionally, as the syngas is at high pressure and contains a relatively concentrated amount of CO2, it is considerably easier to extract the pollutants.
Carbon capture does not come cheap analysis from the US’ Natural Energy Technology Laboratory shows that CO2 capture and compression using a glycol-based sorbent raises the cost of electricity from an IGCC power plant by $0.25 a kWh but it does open up the prospect of totally emission-free power generation.
DTEC technology offers a similar outcome. The process is a modification of ocean thermal energy conversion technology (OTEC), which is based on the temperature differences between deep and shallow seawater. Instead of seawater, DTEC uses the wasted heat and warm effluent wastewater to evaporate ammonia, the vapours of which can power turbines to generate elec-tricity at little cost and without pollution. The ammonia gas is then cooled using cold deep seawater to allow the ammonia to be re-used.
The amounts of electricity and water generated through this process are not huge, but they are significant. On an average world-scale refinery, the installation of DTEC technology can generate 1,000-10,000 kW of electricity and 1,000-10,000 cubic metres a day of drinking water, depending on the configuration. This amounts to a reduction of up to 100,000 tonnes of CO2 a year.
Unlike IGCC, DTEC is in the process of being implemented. Under the terms of a memorandum of understanding signed in April, Japan’s Xenesys, which has pioneered the technology, is designing a DTEC plant at the Mina al-Ahmadi refinery owned by KNPC. The facility will use the heat generated from the cooling processes at the refinery to create electricity and desalinated seawater.
‘The Middle East has a lot of waste heat discharged, without it being utilised,’ says Michinaga Takeda, head of Xenesys’ overseas business division. ‘We have had lots of enquiries from the region about the technology.’
According to Takeda, DTEC may be easier to implement than the more tried and tested OTEC technology because the high temperature of the discharged heat from the refinery means there is a greater temperature differential, and therefore higher pressure.
In theory, a technology such as DTEC makes sense for Kuwait. The state is undergoing a power crisis, with regular electricity outages during the summer months. By using the wasted heat and returning it in the form of electricity to the refinery, DTEC can help reduce the total demand load. If it is replicated at the state’s two other existing and one planned refineries, and at the Equate petrochemicals facility, it could potentially reduce demand by up to 30 MW a significant amount.
Again, the technology is not cheap and requires an outlay of about $10 million-20 million to install. But its proponents claim the savings on power and water will return that investment in five years. Al-Mushailah says if the Mina al-Ahmadi experience is a good one, then the technology can be rolled out to KNPC’s other facilities. Other Gulf states may follow Kuwait’s example.