Energy Management and Operational Efficiency
Has the scope 3 hype distracted the industry from energy efficiency or emphasised the need for the supply chain to become more energy efficient?
By Kiro Tamer
Did you know that 29tWh of electricity was lost in the UK national grid transmission and distribution system?
That’s the equivalent of 10.7 million houses worth of electricity per year.¹
Did you know that construction plant in the UK idles around 40% of the time?
The message I am trying to convey is that Scope 3 emissions are someone else scope 1 emissions and the volume can be dictated by how efficient those initial operations are.
In this article I wanted to focus on a specific process, on site power, and a solution that especially within the built environment we need to overcome and I believe this can be achieved by:
Better understanding/appreciating internal combustion engines
Better understanding/appreciating electrical loads and intensity ratios
Better understanding supporting technologies such as batteries
Better understanding, planning, communicating, coordination of the steps required to power our sites
Let’s start with the demand:
A construction site has many different processes and these processes have many electrical loads and profiles.
If we focus solely on electrically powered equipment, you will find:
Anything which has a motor will have a start-up current and a nominal load
This means that the power needed at the start of the equipment cycle can be 3 to 4 times greater than during normal operations
You will have a seasonal variation
You will have a day and night variation
You will have a production variation
Combine these limited variations and you may find a huge are of inefficiency; where:
In the diesel generator used to power the site
Why:
Because in many cases a single engine is provided to power the entire sites requirements, and this creates the following issues:
Oversized for the nominal load
Underloaded
Unnecessary use of fuel
Increased emissions levels
There are ways to overcome underloaded diesel generators, some of these are:
Specify a generator by process, welfare, lifting, etc etc
For processes where you have motors, such as cranes, you can support the start-up current using high output batteries or fly wheel technology
Load on demand, where a 2 or more generators are linked to provide the powered needed instead of a single generator
For welfare, a battery and generator arrangement may be sufficient, but be careful of the battery throughput, in many cases with batteries available on the market, the throughout is limited to 11kW, which means that if the demand does not drop below 11kW, the generator will not switch itself off…
Now, onto the most obvious option which would overcome a lot of these issues and completely decarbonise on site operations, mains power.
Mains power, shore supply, TBS (temporary builders supply), they are all descriptions of an electrical supply which provides power to a site which is fed from the mains grid.
So why isn’t a mains power connection available for all construction sites, or at least those in the built environment?
The supply chain and stakeholders involve in mains electricity are numerous and its complex, key players:
Distribution Network Operator (DNO)
Operator of the electrical distribution systems, including, overseeing the connections and disconnection of the substations and the available capacity
Energy Supplier
Oversees the electrical supply contract and its pivotal to triggering the workflow of the other stakeholder required, meter operator
Meter Operator
Required for the meter installation, operation and consumption data from consumer to energy supplier
There are the key parties required to either utilise an existing supply, organise the disconnection and/or connection of a new supply.
If you take over an asset, which has a live supply, then a simple change of tenancy (process to move the electrical supply from the previous user to the new one) could allow you to use the supply with immediate effect, but if you require the disconnection of the existing substation and connection of new one, then careful considerations are required.
Key environmental driver of why this is so important?
If the existing substation and new substation is not perfectly coordinated, then the construction site will not have power, and a diesel generator will be required.
So, what are these considerations:
The DNO requires a detail application to be submitted and paid for before a 12 week average lead time starts
A TBS can vary from £20k to £150k which needs to be paid for upfront
Detailed coordination of all the stakeholders is required for the site to have power through the different phases, soft strip, demolition, enabling and construction
If there are interruptions or delays, then a secondary supply will be required, at which stage, this is usually when tower cranes are required which is when either oversized generators or costly hybrid set ups are required.
There are many other practical considerations needed, but the points shared provide the key barriers to overcome and the risks involved of not managing all the stakeholders correctly.
The unfortunate truth is that powering construction sites using mains power requires a good understanding of the processes and the different stakeholders involved.
That is already much harder than simply hiring a diesel generator, a diesel bowser and organising diesel supply to a site and providing power to your site this way.
However, the benefits are huge, in most cases (longer projects/requirements) it will be cheaper to provide your power requirements using mains power and from the very start, it will provide power with zero on site emissions.
Removing diesel from construction is key requirements to drive net zero in construction and removing large volumes of emissions through inefficient use of generators is a must now and this can be achieved now with better planning and appreciation of the steps involved.