12.05.2010
Natural gas, being a clean, efficient source of energy, has innumerable uses in industry, and new applications are being developed every day.
The industrial sector currently consumes more natural gas than any other end-use sector and is expected to continue that trend through 2030, when 40 percent of world natural gas consumption is projected to be used for industrial purposes.
The primary force shaping the demand for natural gas, and other sources of energy, in the industrial sector is the movement away from energy-intensive manufacturing processes, towards less energy-intensive processes. There are two driving forces behind this shift: the increased energy efficiency of equipment and processes used in the industrial sector, as well as a shift to the manufacture of goods that require less energy input. Despite this shift from energy-intensive processes to less energy-intensive processes, the demand for energy is expected to increase in the industrial sector due to greater industrial demand.
There are several factors which could affect the demand for natural gas over other sources of energy to meet the long term energy requirements of the industrial sector. These include:
• The increased demand for efficient natural gas powered applications to replace processes which are extremely energy inefficient, such as for the generation of steam. Natural gas fired combined heat and power systems, as well as natural gas fired boilers, can be much more efficient and cost effective than older boilers running on coal and petroleum. This is especially true if evaluated on a total energy efficiency basis. However, the replacement of older industrial equipment with newer natural gas fired equipment requires an up-front capital investment, which may be extremely high in some situations and requires an expert in equipment and energy efficiencies to examine on a case by case basis.
• The price and availability of electricity in the industrial sector will play a role in determining the demand for natural gas. Natural gas powered distributed generation technologies, as well as combined heat and power applications, offer industrial energy users with attractive alternatives to purchased electricity and enables some industrial energy consumers to generate their own electricity on-site, powered by natural gas. Distributed generation offers great promise in the industrial sector. The reliability and flexibility offered by the on-site generation of electricity is particularly important for the industrial sector, where loss of electricity could have disastrous consequences, including spoiled products for a manufacturer dependent on electricity. Thus, the expansion of distributed generation, and combined heat and power units, could be the next frontier for increased natural gas demand in the industrial sector.
• Natural gas represents a cleaner burning alternative to coal and petroleum use in the industrial sector and the imposition of stringent anti-emissions regulations may serve to increase the demand for natural gas in the industrial sector. Additionally, should an emissions trading market develop (in which, basically, industrial companies are allowed a certain level of emissions ‘credits’, which may be sold if they emit fewer harmful products than they are allowed), the cost of financing new, clean natural gas equipment may be offset by the revenue that may be brought in through the trading of surplus emissions credits.
For industry although natural gas is used extensively, it is nevertheless concentrated in a relatively small number of industries. Natural gas is consumed primarily in the pulp and paper, metals, chemicals, petroleum refining, stone, clay and glass, plastic, and food processing industries. These businesses account for over 84 percent of all industrial natural gas use.
Industrial applications for natural gas include heating, cooling, and cooking. Natural gas is also used for waste treatment and incineration, metals preheating (particularly for iron and steel), drying and dehumidification, glass melting, food processing, and fueling industrial boilers.
Natural gas may also be used as a feedstock for the manufacturing of a number of chemicals and products. Gases such as butane, ethane, and propane may be extracted from natural gas to be used as a feedstock for such products as fertilizers and pharmaceutical products.
Natural gas is extensively used to heat and cool water.
Natural gas is also used in infrared heaters which are able to use natural gas to more efficiently and quickly heat materials used in this process. Natural gas is combined with a panel of ceramic fibers containing a platinum catalyst, causing a reaction with oxygen to dramatically increase temperature, without even producing a flame. Using natural gas in this manner has allowed industry members to increase the speed of their manufacturing process, as well as providing a more economic alternative to electric heaters.
Natural gas is used efficiently in the operation of natural gas Combined Heat and Power (CHP) and Combined Cooling, Heat, and Power (CCHP) systems. For instance, natural gas may be used to generate electricity needed in a particular industrial setting. The excess heat and steam produced from this process can be harnessed to fulfill other industrial applications, including space heating, water heating, and powering industrial boilers.
Since industry is such a heavy user of energy, and particularly electricity, providing increased efficiency can save a great deal of money.
Combined Heat and Power generation (CHP) systems are now being produced on a scale that is safe, practical, and affordable to homeowners as well. CHP technologies sometimes referred to as cogeneration, have provided heat and electrical energy efficiently at commercial and industrial sites for many years. A CHP system uses fuel such as natural gas to produce heat and electricity simultaneously. The electricity can be used for any household device such as lights and appliances. Simultaneously, the heat produced can be used for water heating and/or space heating. About 10% of the fuel used is lost as exhaust, much like a high efficiency furnace.
The engines used in the CHP units for producing electricity can be internal combustion or Stirling (also called external combustion) engines. Micro-CHP, as residential-sized CHP systems are usually called, run on propane, natural gas, or even (in the case of Stirling engines) concentrated solar energy or biomass.
The byproduct of electricity generation is large quantities of waste heat. One 6 kW unit provides 10 gpm of hot water at 140 to 150°F. This waste heat can be used to heat an entire home, water for domestic use, for swimming pools and spas, or even as an energy source for heat-driven (absorption) cooling systems. CHP systems are extremely efficient, offering combined heat and power generating efficiency of between 70% – 90%, compared to about 30% to 40% for electricity from a central power station. Indeed, because CHP systems make extensive use of the heat produced during the electricity generation process, they can achieve overall efficiencies in excess of 70% at the point of use. In contrast, the efficiency of conventional coal-fired and gas-fired power stations, which discard this heat, is typically around 38% and 48% respectively, at the power station. Efficiency at the point of use is lower still because of the losses that occur during transmission and distribution of the electricity.
The benefits of CHP include:
• Cost savings – CHP’s high efficiency leads to a reduction in the use of primary energy. Indeed, since the fuels are used more efficiently less fuel is used. Savings can be between 15% and 40% compared to imported electricity and on-site boilers.
• Lower emissions – less fuel burnt means reduced emissions of carbon dioxide (the main greenhouse gas) and other products of combustion.
• Increased security of energy supply – CHP systems can be designed to continue to operate and serve essential loads during an interruption to mains power supplies, increasing security of energy supplies.
Micro-CHP units range in capacity from about 1 kW to 6 kW and are about the size of a major appliance. Installation may be performed initially by specialists and, after the technology matures, by an experienced plumber, electrician, or expert technician. One unit with a new small capacity engine simultaneously produces 1.2 kilowatts of electric power and 11,000 Btus of heat in the form of hot water. The system is combined with a high efficiency, natural gas-fueled warm air furnace or boiler for supplemental space heating. The primary challenge for getting the highest efficiency and best economic return on CHP is to fully utilize all of the thermal energy produced when generating electricity.
CHP can be used to provide energy to anything from a single home to a large industrial plant. Unlike conventional power plants, CHP units are sited close to where their energy output is to be used. The main criterion is that to make the investment worthwhile, there must be a need for both the heat and electricity produced by the CHP unit.
In the home, a microCHP unit will provide both heat for space and water heating, but also electricity to power domestic lights and appliances. MicroCHP units are a very new technology only recently appearing in the European market. For commercial buildings and small industrial spaces, a factory-assembled, packaged CHP system is appropriate. Here, an electricity generator, heat exchanger, controls and either an engine or a turbine is packaged together into a CHP unit that can be connected to the heating and electricity systems of the building. Some building types, particularly those that need a lot of energy, or operate around the clock, are particularly suitable for CHP, such as leisure centres, hotels, hospitals, etc. CHP systems can, with the addition of a chiller, supply cooling for air conditioning systems as well as heating – such an arrangement is often called a ‘trigeneration’ system or CCHP. Industrial CHP plants tend to be designed and built individually to fit the industrial process they serve. These CHP plants are based on gas turbines, steam turbines or engines, together with electricity generators and control systems. The very largest CHP plants rival traditional power-only plants in size and deliver huge quantities of energy – but at a much higher efficiency. Some industrial processes are particularly well-suited to CHP, those that use lots of heat and operate around the clock – the manufacture of paper, chemicals, food and drink products, as well as refineries, are among those that can benefit most from CHP.
The industrial sector is also subject to regulations regarding harmful emissions, and the burning attributes of natural gas help industry to reduce its emissions.
Natural gas co-firing technologies are also used efficiently in industry. Co-firing is the process in which natural gas is used as a supplemental fuel in the combustion of other fuels, such as coal, wood, and biomass energy. For example, a traditional industrial wood boiler would simply burn wood to generate energy. However, in this type of boiler, a significant amount of energy is lost, and harmful emissions are very high. Adding natural gas to the combustion mix can have a two-fold effect. Natural gas emits fewer harmful substances into the air than a fuel such as wood. Since the energy needed to power the natural gas boiler remains constant, adding natural gas to the combustion mix can reduce harmful emissions. In addition, the operational performance of the boiler, including its energy efficiency, can be improved by supplementing with natural gas. For instance, in wood fueled boilers, adding natural gas can compensate for the use of low grade wood, allowing it to combust more quickly and completely. This type of co-firing can also be used in the generation of electricity, whether on-site or in a centralized power plant.
Residential and commercial uses of natural gas:
Residential energy demand in the US for instance accounts for 22% of all natural gas consumption and is expected to increase about 1% a year until 2025.
Probably the most important long term driver of natural gas demand in the residential sector is residential heating applications with increasing numbers of new homes being built using natural gas to heat them. There is a commensurate decline of sorts because on the other hand the natural gas furnaces used to heat the homes are becoming more efficient and thus need less gas.
With time there will be advances in distributed generation to replace electricity and in residential natural gas cooling technologies (currently most cooling is done with electricity). This is especially important since in terms of total energy efficiency (TEE) measured directly from the source, natural gas is often much more efficient than electricity.
Indeed, natural gas is extremely efficient, losing very little of its energy value as it reaches its point of end use. Electricity, on the other hand, measured from the point of generation to the wall socket, is much less efficient. In fact, only about 27 percent of the energy put into generating electricity is available by the time it reaches a home. Thus, while an electric appliance may be extremely efficient in using the electricity it takes from the wall socket, this does not take into account the energy that is lost in generation and transmission.
Currently, the majority of energy used by the commercial sector is in the form of electricity. Similarly, many common household appliances can only run on electricity. The advancement of natural gas technology in the form of offering natural gas powered applications that may compete with these electric operated appliances may provide a huge increase in demand for natural gas. Natural gas cooling, combined heat and power, and distributed generation are expected to make inroads into those applications that have traditionally been served solely by electricity.
Commercial usages:
Natural gas can replace other forms of primary fuels such as LPG, such as in a bakery that has an oven that is heated with LPG gas in canisters could potentially be operated more cheaply by using natural gas. Each customer’s LPG usage needs to be calculated on an individual basis and then based on the calorific value of the LPG and the gas, this value can relatively easily be converted into natural gas terms by a heating engineering expert.
What you cannot do, is to replace KWH of electricity by MMBTU’s of gas. You cannot feed natural gas into an electric bulb for instance to obtain lighting. Nor can you convert an electric oven to operate on natural gas instead. What you can do, if economically worthwhile, is to replace the electric oven to one that would run on natural gas. For this, detailed economics need to be worked out by a heating/boiler/furnace/energy expert to calculate the upfront capital investment of the new oven as well as the ongoing operational costs of the oven on natural gas compared to the old electric oven to understand whether this operation is economically worthwhile. This would require a very specialized individual with in-depth knowledge of heating applications, knowledge of the type of burners/boilers being used, which appliances can be converted and/or replaced economically, what processes benefit more from natural gas versus other fuels, versus electric appliances. Need of course to include the costs of laying natural gas pipes to the end consumer. Although one can easily convert tons of LPG into mmbtu’s of natural gas, a specialized heating engineer is required to understand whether a particular model of oven can be converted from one fuel to another.
