22 Aug 2017

Natural Gas - a cleaner and cost-effective solution

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Natural Gas – a cleaner and cost-effective solution 

More and more companies have started to use natural gas generators for power generation. Not only is it a cleaner burning fuel than diesel, with the lower exhaust emissions, natural gas is also cheaper. Aggreko uses “Lean Burn” technology to squeeze more power and efficiency from generators, which can provide up to 50% fuel savings (when compared to diesel). 

In their push to optimize field operations, companies continually look for new ways to boost their long-term production, while keeping costs down and minimizing any impact to the environment. In-field power generation is one area receiving particular attention in this regard. 

While diesel fuel has reliably powered equipment for decades, cost and emission concerns of diesel make may not always make it the most optimal choice. Natural gas-powered engines and generators are growing in acceptance as a viable and cost-effective alternative to diesel, particularly when a reliable supply of natural gas is available. In the oil and gas industry, for instance, even in tight oil plays, most wells produce some amount of associated natural gas that could be used to power in-field generators, pumps and other equipment.

The benefits of rental natural gas generators

Among the benefits that natural gas fuelled generator systems provide over conventional diesel systems is their economic advantage in the long term. While natural gas units carry larger upfront capital expenses, they have been shown to cost 40-45 percent less to operate than diesel units, primarily because of the fuel savings. These units also generally exhibit longer run times between service intervals compared with their diesel counterparts, thereby maximizing field uptime. 

Moreover, natural gas-powered units also provide the option to use field-proven, lean-burn technology to meet the most demanding emissions guidelines at both federal and state levels, or rich-burn technology that can handle high-Btu gas that would otherwise be flared or left stranded. The U.S. Environmental Protection Agency (EPA) estimates that natural gas produces 85 percent fewer emissions than diesel, and has a 25 percent lower carbon footprint.

For operators and plant managers to take full advantage of the benefits of natural gas-fired power generation, they must develop a power management strategy that is flexible and scalable to meet the needs of each stage of field development. Such a strategy can be developed best by partnering with a natural gas power generation provider over the long term.

The best approach is one where the power generation and distribution equipment provider works in consultative collaboration with the producer. The power provider is involved early on to both understand the operator’s field development plans and to offer the best around-the clock power management solutions that will grow or decrease while demand changes. 

Natural gas power generation for the Oil and Gas industry

Let’s take an example from the Oil and Gas industry. In the Mississippian Lime play, an operator was developing assets in remote areas without grid power. The operator needed to be prepared to scale up when wells started producing, and started to investigate alternate power solutions. The ultimate goal was to select a power solution that would afford more efficient growth plans.

Aggreko worked with the operator to develop a scalable, temporary natural gas power solution that would address different growth phases and shifting drilling locations. First, as the wells were coming on line initially, a mobile natural gas generator utilizing well gas was installed. 

Once overhead power lines were installed, 40 small generator sets were removed and replaced with a single, natural gas micro-grid hooked directly into the operator’s well gas and connected to the overhead power lines.

Over 18 months, the micro-grid (which included four 1.3-megawatt containerized natural gas-fired units) was used to position the operator’s power requirements for optimal efficiency. Further efficiency improvements came from using remote monitoring technology, which helped monitor system capacity and proactively address any issues that surfaced. 

The micro-grid approach brought reliable and consistent power to the developing field–an approach that the operator could easily replicate as needed as drilling locations shifted. The central power plant design included built-in redundancy and uptime comparable to the grid, and the natural gas fuelling option delivered power at a fuel savings of roughly 75 percent, compared with diesel. 

Regardless of its size, any natural gas power generation system should address a number of issues. First, the system must be capable of running efficiently on natural gas of varying Btu levels and from different sources (wellhead, LPG, LNG, CNG and pipeline gas). The system should be able to deal with intermittent supplies of natural gas and automatically switch to another fuel option, if necessary, without causing delays or interruptions in field production. And, ultimately, the power system must run reliably for long periods with minimal requirements for maintenance or downtime.

The latest generation of power generation systems successfully addresses these challenges
to supply reliable, abundant and cost-effective power to a growing number of customers throughout North America and across the globe.

Emergency rentals

Natural gas generators can also be used for emergencies. Back in 2012, Hurricane Sandy caused massive power outages and floods. The Siphon Tunnel project, a $250 million infrastructure investment to put a new water siphon in place between Brooklyn and Staten Island, was entirely flooded with salt water, causing a complete loss of electricity and severe damage to the equipment. The results: substantial loos of capital and major delays.  

The construction team needed an immediate power and low-emission solution. We designed a comprehensive solutions package of three 1300 kW natural gas generators, with transformers and distribution, to ensure continuous power for emergency systems.  

In the absence of grid infrastructure, the configuration served as a temporary substation utilizing two of the gas generators as prime power, and the third as a backup – all of which operated in parallel, providing 3.9 MW of continuous operation to the site. Due to the use of natural gas generators, we could provide an estimated cost savings of $125,000 per month in fuel over two years (or $3,000,000 throughout the whole project). 

Natural gas generators for turnarounds

From an industrial standpoint, we can use an example from the petrochemical and refining sector. During the planning phase of a large turnaround, a Mid Continent refiner (195,000 bpd) identified the need for a significant amount of temporary power. Previous turnarounds had always relied on diesel generators. However, there was recognition from the site’s environmental leaders that this would create additional emissions, something plant management was keen to avoid. 

When we presented a case for switching to natural gas as a fuel source, the customer was quite intrigued. Not only would their emissions issues largely disappear, the cost of fuel would also decrease significantly. The natural gas generators used for this turnaround reduced NOx emissions by over 80%, which was very important for the refiner as they consistently operate close to their permitted limits. 

The application saved $250,000 in fuel costs and avoided the logistical hassle of frequent diesel fuel deliveries. The customer also had the benefit of using Aggreko Remote Monitoring which provided 24/7 live monitoring of the generator throughout the entire turnaround by trained technicians.