Embracing Natural Gas
For decades now, U.S. colleges and universities have led the way in areas such as research and technology development. Today, many are leading the way in showing how an education institution can become both an economic and environmental steward. Some institutions are achieving this by making natural gas their primary energy source.
The positive benefits of natural gas are numerous. For starters, it costs less: The U.S. Energy Information Administration (EIA) has projected oil to be two to three times more costly than natural gas through the year 2035. Meanwhile, natural gas CO2 emissions are 25 percent less than oil, while nitrogen oxides and sulfur dioxide emissions are significantly lower.
But perhaps most important, natural gas can help bring America much-sought-after energy independence, as well as create new jobs. According to the EIA, it’s estimated that the United States possesses a total resource base of 2,203 trillion cubic feet (Tcf) of natural gas that is technically recoverable. Based on the 2011 rate of American natural gas consumption (24 Tcf per year), this 2,203 Tcf of natural gas is enough to last about 92 years. The large total in estimated gas supplies is largely thanks to new drilling technologies that are unlocking substantial amounts of natural gas from shale rocks. The EIA estimates that the unproved technically recoverable resource of shale gas for the United States is482 trillion cubic feet.
Overall, this supply of natural gas could not only help guarantee domestic energy independence, but also, according to the business and economic research firm IHS, create as many as 1.5 million shale gas-related jobs by 2015.
What institutions are doing
In an effort to improve natural gas infrastructure, midstream pipeline gas companies have proposed to invest about $8.2 billion a year through 2035. Many institutions of higher education have taken advantage of these improvements. They have connected to pipelines, and have either retrofitted existing coal- and oil-fired plants to burn natural gas or constructed new gas-fired facilities.
For example, the University of Southern Maine (USM) converted its Portland campus’ central heating plant from oil to natural gas. This changed reduces USM’s carbon output by 1,048 metric tons per year and saves USM about $315,000 next year in utility costs. No. 6 oil was used on the Portland campus for decades with USM burning an average of 280,000 gallons annually for heat.
Similarly, South Dakota State University, Brookings, switched from burning coal to burning natural gas in its physical plant’s boilers. Natural gas has helped lower the university’s overall energy costs. Despite the university’s increase of square footage in recent years (around 400,000 square feet between 2009 and 2011) and a significant increase in the size of the student body, the cost of energy has decreased per square foot. The price now is just $1.68 per square foot and utility costs are $401.12 per full time student a year. Other universities with the same type of buildings and research operations range on average between $600 and $700 per student.
Other colleges and universities are taking another route: closing their coal- and oil-fired plants, and constructing new gas-fired facilities.New York University installed a natural gas-fired combined heat and power (CHP) plant. Compared with the university’s former oil-fired CHP plant, the upgrade decreases greenhouse gas emissions by 23 percent while reducing air pollutants by 68 percent. Situated beneath a renovated public plaza, the new CHP plant approaches 90 percent energy efficiency while producing 13.4 megawatts of electricity, twice the output of the previous system. The plant is expected to save the university $5 to $8 million in annual energy-related costs.
Upstate, Cornell University in Ithaca, N.Y., installed a 15,000-square-foot, natural gas-fired CHP facility that produces up to 30,000 kilowatts of electricity per year (or about 70 percent of campus usage). An interstate natural gas pipeline is situated about three miles from campus, and Cornell has installed and owns a spur from that line. The university, which previously used a coal-fired CHP plant, has cut its carbon emissions by nearly 30 percent or roughly 75,000 tons annually. Discontinuing coal also saves 100,000 gallons a year of diesel fuel used by trucks that deliver the coal to Cornell from West Virginia coal fields.
Unfortunately, there are many colleges and universities that cannot be served by a natural gas pipeline in the immediate future. However, these institutions can still make a commitment to natural gas by using either liquefied natural gas (LNG) or compressed natural gas (CNG) as a primary fuel source.
Compressed natural gas
CNG is similar to the natural gas from a pipeline, only it is stored under very high pressure. Current pipelines compress natural gas to nearly 1,500 pounds per square inch gauge (psig); CNG is roughly 3,600 psig.
CNG as a base load fuel for industrial/commercial customers is a relatively new concept in the United States. CNG traditionally has been used for short-term applications in connection with emergency services and maintenance activities in the natural gas utility industry.
Using CNG as a base fuel load in a commercial/industrial setting requires specific equipment and operational facilities. For starters, CNG is transported by CNG tube trailers. These vehicles typically have a gross capacity of about 160,000 standard cubic feet. However, there are newer composite tube trailers constructed of high-density polyethylene that allow for the transport of about 300,000 standard cubic feet. The U.S. Department of Transportation recently has granted approval for the transport of the composites on U.S. roadways. The CNG tube trailers typically are owned and operated by the CNG supplier, so the college or university would have no involvement with tube trailer off-loading.
A CNG base fuel load application consists of compressor (or “mother”) station and an off-loading (or “daughter”) station. A “mother” station will be at a location where the tube trailers receive CNG from the pipeline. The “mother” station features a compressor and tube trailer loading facility to load multiple trailers at 3,600 psig. It’s preferable to have this location sited within a 100-mile radius of the customer site to reduce travel time. A college or university would not have any responsibilities associated with the “mother” station.
The “daughter station” features off-load equipment at the institution, including a minimum of two tube trailer off-load bays. Off-load systems—furnished by the CNG supplier—are equipped with a heating system to warm gas during depressurization.
The piping systems fed by the “daughter” station can be carbon steel for above-ground applications and high-density polyethylene for buried piping systems.
In terms of cost, CNG suppliers are currently quoting prices around $14/MMBtu. Such costs cover equipment leasing agreements and deliveries of CNG. A college or university will need to provide an adequate site, oil burner conversions, and piping that connects end-use equipment to the CNG source. However some CNG suppliers may roll those costs into a financing package.
Liquefied natural gas
LNG is natural gas that has been cooled to minus 260 degrees Fahrenheit. At this temperature, the gas condenses into a liquid and takes up 600 times less space than in its gaseous state, making it more practical to transport long distances.
In the U.S., LNG has been used both commercially and industrially since the 1940s. LNG often is used to supplement a gas utility distribution system when demand is beyond the capacity of what the pipeline can deliver to its customers. LNG is stored at peak-shaving facilities, which are equipped with vaporization systems to inject natural gas into the pipeline during periods of peak demand (e.g., winter). Of the approximate 113 active LNG facilities in the U.S., 57 are peak-shaving facilities. The other LNG facilities include marine terminals, storage facilities and operations involved in niche markets such as LNG vehicular fuel.
The LNG delivery model and associated pricing differs from CNG. With LNG, the end user is responsible for the upfront capital expenditure of the LNG facility. The end user then contracts directly with the LNG supplier and transporter for supply and delivery of the LNG. Delivered LNG is currently in the range of $10 to $12/MMBTU.
LNG requires infrastructure that is unique from the infrastructure used for CNG. This includes LNG storage tanks. These typically are 15,000 gallons or more in size and are insulated to maintain a fluid temperature of about minus 260 degrees Fahrenheit. A vaporization system will be necessary to convert LNG back to a gas form.
Vaporization systems are needed to convert LNG back to a gas form for use at the site. Ambient vaporizers use heat sink from ambient air to warm LNG to a vapor state. This type of vaporizer does not require a heat source derived from additional combustion equipment. Many users opt for the ambient form of vaporization to reduce emissions and economize on fuel costs. However, where ambient temperatures reach sub-freezing temperatures supplemental trim heaters will be needed to support the fuel supply demand.
Heated vaporization systems, such as a shell and tube heat exchanger with a boiler or a water-bath vaporizer, can also be used.
Service pipes convey the vaporized LNG from the storage area to end-use equipment. As noted above, trim heaters may be required immediately downstream of ambient vaporizers to maintain a minimum outlet temperature of 40 degrees for the send-out gas. These heaters are typically electric units. However, if waste heat is available, it can be used for heating the vaporized LNG.
The production of LNG results in the removal of odorant present in the pipeline gas. Therefore, an odorant injection system will be installed just downstream of the trim heater and upstream of the service pipeline. The LNG facility will be equipped with combustible gas detectors and cold temperature sensors for the detection of an LNG leak.
Finally, an off-load pump will be needed to transfer the LNG transport contents to a receiving tank. Additional pumps may be required to assist with managing the tank inventories if multiple tanks are required. A concrete sub-impoundment system is used to contain a spill from an LNG transport. The impoundment is typically sized for 13,000 gallons and is located adjacent to the storage tank impoundment.
Tremendous benefits
U.S. colleges and universities are beginning to understand the tremendous benefits natural gas can bring. However, these benefits extend beyond the reduction in long-term energy costs and the emissions that inevitably result from burning oil and coal.
By utilizing natural gas and supporting an ever-growing movement for energy change, institutions will become more enticing to students and faculty, draw new sources of funding, and increase the support of alumni and local communities.
Nicoloro and Fontaine are with Fuss & O'Neill, Manchester, Conn., a leading design and planning firm that has overseen many cutting-edge projects throughout the United States.
