Case Study - Severn Tunnel electrification

Introduction

The use of temporary site lighting has been part of the construction site landscape for many years.  Traditional diesel generator lighting towers in their various guises, have seen some development over recent years in aiming to reduce power consumption and diesel usage as well as inherent noise associated with the equipment.  These developments have been welcome, however, the major issues still remain with diesel powered lighting.  These include:

Noise - noise can still be an issue on certain sites particularly in the urban environment, even with the most efficient diesel generator. 

Maintenance – Ensuring the generator has sufficient fuel for continued operation requires manpower.  When considering single units this may not seem great, however on the larger sites where multiple units are used for extended periods of time, the man hours required for maintenance can be significant.

Environmental challenges – The use of fuel on site in itself presents environmental challenges. From the storage of the fuel to the emissions created by the use of the fuel.  Carbon footprint with the use of even the most energy efficient generator can be considerable when evaluating over the entire project.  Air pollution in the urban areas has seen particular close attention from authorities a good example being the London Mayors Office imposing non-road mobile machinery emission standards.  The key air contaminants from incomplete combustion of particulate matter, NOx and SOx are all apparent in diesel powered generator lighting.

 

Mobile Solar Powered Lighting Tower

Prolectric are off grid renewable experts and have been working in the solar sector for more than 15 years.  The company has extensive experience of providing solar lighting solutions that are suited to the challenging UK winter.  The track record includes approximately 1,000 solar street lights operational across the UK on both permanent and temporary sites, with continued performance through many UK winters. This experience led to the development of the Pro-Light Mobile Solar Lighting Tower, offering year round performance as a ‘use and forget’ solution to customers.  The ProLight is a 100% solar powered option that provides many benefits and advantages over that of both conventional diesel and other hybrid solutions on the market.  Taking each of the issues related with diesel powered lighting referred to above, the Prolight addresses each in turn as follows:

Noise – Zero Noise.  As there is no diesel powered generator the battery powered lighting has zero noise associated with it, making it ideal for noise sensitive sites.

Maintenance – Zero need to refuel.  Manpower can be better utilised elsewhere on the project.  Further, Prolectric are able to monitor and control each ProLight remotely through our in-house web portal.  The portal can also be used for monthly reporting on carbon savings, energy generated and energy consumed.  Providing peace of mind that someone is looking after the asset while the customers focus on their job at hand rather than being concerned about the operation and performance of site lighting.

Environmental – No fuel = zero carbon emissions during operation.  Any issues with fuel spillages become non-existent with the use of the ProLight.  Significant carbon savings can be achieved with the use of the ProLight compared to standard diesel powered generators, see references below.  Air pollution is also completely addressed with the use of the ProLight.  All batteries used in our ProLight Mobile Lighting Tower are recycled for future use.

 

Data Comparison

The following data sets compares the use of a typical diesel powered generator compared to that of the ProLight solar powered lighting tower as used on a specific site and also compares the impact of utilising the solar version versus the diesel version over the space of one year.

 

Case Study - Severn Tunnel Electrification Works, Filton Airfield Site Compound

ABC Electrification wished to utilise the Pro-Light solar lighting tower on the site compound on this fast track 6 week programme of the Severn Tunnel electrification works for Network Rail.  The site was in use 24/7 for a 6 week period between Monday 12th September 2016 to Sunday 23rd October 2016.

Site Lighting Mode of Operation: The client required 12 hours per night constant operation for the duration of the works.  The requirement was for automatic switch on at dusk and automatic switch off at dawn.  This requirement is easily accommodated within the Pro-Light, with either manual programme adjustment on site or remote control via our web portal.  The pictures below shows the unit in situ.

  

The unit operated successfully for the duration of the time on site with no man intervention/maintenance, zero noise (note the close proximity to the site cabins), zero fuel needs and zero carbon emissions.

The following information highlights the environmental impact of using a diesel generator lighting tower compared to that of the ProLight. There are a variety of diesel generators on the market, all have differing specifications.  Listed below are the most common found in the UK with their respective performance data.

Diesel Tower Model

Fuel Tank Capacity (l)

Run Time (hrs)

Power Demand (w)

Litres of diesel per kWh

VT1

116

65

4000

0.446

VT2

31

26

1600

0.745

VT Hybrid

160

700

600

0.381

VB9

170

320

1600

0.332

Table 1- Typical Lighting Towers in Use in the UK

Applying the site compound requirements to the above typical diesel generator lights would have resulted in the following outputs for the site compound:

Diesel Tower Model

Run Time (Hrs)*

kWh for the project duration

Diesel Used (litres)

Kg CO2 e for 1 light

VT1

504

2016

899

2409

VT2

504

806

600

1608

VT Hybrid

504

302

115

308

VB9

504

806

268

718

*12hours per night for 42 nights

 

What can be noted from the above table is the wide variety in performance between the typical units in operation across the UK.  Diesel usage ranges from 115 litres on the VT Hybrid to 899 litres on the less efficient VT1.  The corresponding amount of ‘in use’ CO2 emissions ranges from 308 Kg to 2409 Kg for the same units. The least efficient diesel powered generator is shown to be the VT2 with it requiring 0.745 litres of diesel for every kWh of demand.

 

A summary of the comparison between the use of ProLight and diesel powered lighting in the key areas of noise, Kg CO2e, diesel requirements is shown below.

 

Light Tower Model

Noise Level dB

KgCO2e

Diesel Used (litres)

Man Hours

VT1

65

2409

899

4

VT2

67

1608

600

10

VT Hybrid

65

308

115

0.5

VB9

92

718

268

1

PROLIGHT

NIL

NIL

NIL

NIL

 

As can be seen, the use of a ProLight solar powered lighting tower far outperformed that of diesel powered lighting in terms of the operating costs and environmental impact on the site at Filton Airfield, with zero noise, zero maintenance, zero diesel and zero carbon emissions.

 

 

 

 

Annual Savings

The previous case study shows the difference between a single Pro-Light solar lighting tower compared to the various diesel alternatives.  Taking the savings seen on one project and applying across a sites annual use, assuming 4300 or darkness per annum, the following table shows the annual savings achieved by the use of the solar powered option.  Examples of 1 tower up to 100 towers on any one particular site is presented to show savings in terms of carbon emissions, diesel costs and estimated manpower for the most efficient diesel option, the VT Hybrid unit as follows:

VT Hybrid Diesel Generator Lighting Comparison

ProLight Number

Carbon Emission* Saving Kg CO2e

£ saving

 

Estimated Diesel Usage Saving (l)

Diesel Cost Saving**

Manpower Costs Saving***

Total £ Saving per annum

1

2,567

983

£ 491.50

£ 153

£ 644.5

10

25,670

9,830

£ 4,915

£ 1,530

£ 6,445

50

128,350

49,150

£ 24,575

£ 7,650

£ 32,225

100

256,700

98,300

£ 49,150

£ 15,300

£ 64,450

*Estimation based on VT1 Hybrid

**Diesel cost of £0.5 per litre

***Manpower costs estimated at £25 per hour rate taking 1.0 hour to fill the generator

 

As mentioned the table above highlights the use of one of the most efficient diesel generators on the market - the VT Hybrid. Figures 1 and 2 below show the same savings data presented graphically for the VT Hybrid.

Figure 1- Carbon Savings Achieved

Figure 2- Direct Cost Savings Achieved

 

Should the ProLight unit be compared to say the lesser efficient VT2 the corresponding values of CO2 emissions and diesel usage would be more than 5 times greater than the VT Hybrid and are presented below. 

VT2 Diesel Generator Light comparison

 

 

Carbon Emission* Saving Kg CO2e

£ saving

 

Estimated Diesel Usage Saving (l)

Diesel Cost Saving**

Manpower Costs Saving***

Total £ Saving per annum

1

13,996

5,222

£ 2,611

£ 4,212

£ 6,823

10

139,958

52,223

£ 26,112

£ 42,115

£ 68,227

50

699,789

261,115

£ 130,588

£ 210,577

£ 341,135

100

1,399,578

522,231

£ 261,115

£ 421,154

£ 682,269

 

Summary

The numbers presented above show significant cost savings as well as demonstrable environmental benefits with the use of a robust tried and tested solar powered lighting solution for temporary works compared to more conventional diesel powered lighting.  In addition to the environmental benefits and costs savings the use of remote monitoring and maintenance offered by Prolectric provides peace of mind in the knowledge that the units will provide consistent year round operation even in harsh UK winters months.

Energy saving and the consequent carbon reduction are drivers for most business, providing both cost and environmental improvements.    The use of the ProLight solar powered lighting tower enables both carbon reduction and cost savings with the use of a robust ‘failsafe’ solution to the end user.  With more and more companies setting carbon reduction targets within their business process and activities, such reductions from a single change of equipment can be significant when used more widely.


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