BY MARK STAVRAKIS SR.
AGGREKO TECHNICAL SALES SUPPORT – NATURAL GAS GENERATORS
The hottest year ever recorded in human history was 2015, and it was also the year the globe crossed the symbolic threshold of over 400 parts per million of carbon dioxide in the atmosphere. Taking care of the environment now has never been so critical. With the unseasonably warm trend and increasing number of construction projects expected to continue into 2017 and beyond, contractors are sure to look for power solutions that not only increase operational efficiencies, but also meet stringent environmental regulations.
Many construction companies are turning to mobile natural gas power generation. The use of natural gas power equipment provides significant benefits, allowing construction companies to avoid project delays, improve emissions and make gains on their balance sheet by avoiding high-cost capital expenditure (CAPEX) commitments on short- to mid-term duration needs.
Further, natural gas rental units provide a much cleaner and more cost-effective option than other alternatives — including rental diesel units — to reach compliance. When used for long-term, continuous operation, natural gas units have been shown to offer total cost savings of 40–45 percent compared to diesel units, primarily due to savings in fuel. Natural gas also burns approximately 85 percent cleaner than diesel.
When considering a mobile natural gas power solution, it is important that the equipment match the specific demands of the environment. Each construction project is unique and has different needs, so there is no such thing as one size fits all. Therefore, it is critical to work with a rental utility provider that understands how to design an alternative-fuel power system that seamlessly ties into a construction process. This ensures continuity along the entire life cycle of a new or existing construction project.
Here are two ways solutions deployed in the construction industry supplemented vital power needs, maintained productivity from both an economical and operational standpoint, and met emissions requirements.
A company was bidding on the construction of a $250-million infrastructure investment to install a new siphon water tunnel under the Hudson River between Brooklyn and Staten Island, New York. Unfortunately, there was insufficient power available at the site for all the activities required for the project. In addition, the local utility was behind schedule in providing the necessary power, possibly jeopardizing the project timeline. If the contractor could not maintain the tight schedule, they would face severe monetary penalties. They were in dire need of a power solution that had to abide by the contractor’s corporate commitment to use greener sources of energy where possible.
The most significant demand was power for the tunnel boring machine, a large, complex machine costing more than a million dollars that drills the tunnel hole. Power was also needed for a freeze plant that chills water and then pumps it through tubes into the ground to firm the ground and prevent a cave-in. There were also miscellaneous electrical service requirements for trailers, ventilation, water pumping, atmospheric monitoring and lights.
Moreover, the project was located in a residential area where there was no source of industrial power. One problem with running diesel generators in a residential area is they are noisy and consume a large quantity of diesel fuel. In addition, there’s always the possibility of spills. Because this was a water tunnel, the possibility of a spill was especially worrisome for the customer.
The project also encountered EPA and environmental limitations that prohibited the use of equipment over a certain size. In order to meet the overall environmental limitations, the plan was to lower emissions in the project’s nonattainment area, a zone considered to have air quality worse than the National Ambient Air Quality Standards as defined in the Clean Air Act.
The customer obtained a mobile power provider that met the requirements with three 1,300 kW natural gas generators that were used along with appropriate distribution equipment. A self-contained diesel unit and double-walled tank were also provided in the event that there was a gas power interruption. This ensured continuous power for emergency use in case of any problems. Using natural gas lowered emissions by more than 80 percent, provided an estimated fuel cost savings of $125,000 per month over the next two years and avoided the possibility of a significant environmental incident.
PROTECTING OUR ASSETS
A large Border Patrol station was being constructed in a remote area near Del Rio, Texas and was not yet connected to a utility grid power source. The customer was therefore in need of a mobile power provider to continue construction efforts. However, the project faced many challenges.
Upon retaining a power supplier, the customer requested one diesel generator that could energize all their site needs. However, they didn’t realize that the generators would need to be powered down occasionally for fuel and oil service. For a diesel generator, typical maintenance cycles range from 250 hours for a fuel service to 450 hours for oil service. By using a combination of natural gas-powered generators, there was no downtime. While one generator was being serviced the remaining generators would carry the load.
There was also the issue of how to obtain fuel for the generators given the remote location of the construction site and no local supply of natural gas. The power provider recommended partnering with a supplier of liquefied natural gas (LNG), who would truck the product in and have it vaporized by regasification equipment for use with generators.
Lastly, the project had environmental emissions limitations. Motors above a certain size were forbidden. To help meet the stringent emissions limits, one MW generators were used even though they required more equipment than was called for in the original design.
The final turnkey solution that the mobile power provider delivered included three 200-kW natural gas units, a partner-provided 15,000-gallon tanker of vaporized LNG, fueling service and maintenance.
The LNG-powered solution provided project benefits beyond just reduced environmental impact. The customer also reaped significant economic gains since this approach also required fewer fuel drops. Refueling the 15,000-gallon LNG tanker was only required every 12–20 days based on the engineering estimate of fuel consumption for the application — versus refueling a 2,300-gallon diesel external fuel tank every other day.