Uncertain project pipelines and project-by-project budgeting in the GCC are leading to the capital expenditure-driven procurement of temporary power and resulting in the use of inefficient generator combinations in applications such as the powering tower cranes, say industry experts.
During an industry roundtable conducted by PMV Middle East, experts from Himoinsa, JCB and GENAVCO, the UAE distributor for SDMO, tower cranes were highlighted as an example of a typical rental application where contractors frequently opt for inappropriate genset specifications.
In a typical application, a contractor might set up a 200kVA to 250kVA generator for a tower crane, but as Daniel Crossan, project manager at Himoinsa Middle East, explains: “Tower cranes is a really difficult application, because that generator is generally between 60% to 80% oversized for the job.
“You only need that power when you’re given a big hoist lift, but it will be running idle or on a low load for long periods of time. It’s a nasty combination that results in the coking and shock-loading of the engine, and electromechanically, it’s not what you want to be doing.”
Faisal Hamze, Middle East manager for JCB Power Products, concurs: “Running generators at low power and low load is not good for long life and the performance of the engine, and the same is true for high load. So you need to be running it in a continuous application at around 75% of its capacity.”
This is far from an ideal scenario for rental operators, as Crossan notes: “For a six month contract, they might be spending a quarter of the revenue from that job on the maintenance and the overall procedure, so it’s always a difficult trade-off with getting the right product application.”
And while the rental operator will be burdened with the service of the machine, including the filter and oil changing, Hussein Elkashef, sales manager for SDMO at GENAVCO, notes: “The contractor only have to pay for the operational costs, so the diesel, and they will not even necessarily feel that expense that much.
“For a 200kVA, the governor will link the fuel consumption to how much you are loading your machine. The diesel consumption for 25% of the output is not like it would be for 50% or 75% of the output, but there is a base of consumption of not less than 25% of the maximum fuel consumption.”
Low diesel prices also mean that fuel is still not a leading driver in the Middle East, and Crossan adds: “Even when the fuel price was really high, this was still the model. A lot of engineering can go into these applications, but it just doesn’t seem to be something anybody is looking at.”
But the situation is environmentally problematic, as Crossan notes: “Over and hour period, the crane might do five or six lifts in that hour, but you’re running that genset continually, and a 200kVA genset might burn 100 litres an hour – so you can imagine how much can burn over an entire project.”
The irony of such problems in the construction-oriented rental sector is that an efficient and cost effective solution does exist – it’s just not necessarily economically viable with the context of the current norms of project and procurement budgeting in the region.
In the case of tower cranes, a 120VA generator set might be paired with a battery pack to provide a boost of energy as and when required for lifting operations. Instead of shock-loading the generator, the crane can simply draw that extra capacity required for its intermittent lifts from the battery pack.
The caveat is that such solutions come at a cost, as Crossan notes: “That special application of the genset is probably 70% more expensive than what you’d have for a standard genset.”
Elkashef explains: “The procurement guy will only be looking to the price; he’s not going to be looking to how much he’s going to save in terms of the total cost of ownership later on whether it’s in terms of the fuel consumption, the service costs or the lifetime of the engine.”
To read the full discussion on temporary power, see October’s 2017 issue of PMV Middle East.
