LNG consists mainly of methane, which has a boiling point of –164 0C and for liquefaction requires cryogenic insulated tanks at about atmospheric pressure. Recent practice has been to liquefy the gas that is normally flared in oil fields in remote areas, but it can also be made from landfill gas when purified. LNG is about 1/614th the volume of natural gas at standard temperature and pressure, making it much more cost-efficient to transport over long distances, especially where pipelines do not exist. Similar to LPG, this portability is a major asset. LNG is used in transport and in heating and cooking as well as in industry and as a chemical feedstock.
Liquefied petroleum gas (LPG) is a mixture of propane  and butane , which are gases that become liquid under pressure and can then be stored in pressurised containers (Dell and Rand, 2004). The proportion of each gas varies depending on the source and climate. Propane is preferred where the climate is cold and butane where it is warm. LPG has a high energy per unit volume and is convenient to use. Its calorific value per unit volume is about 2.5 times larger than that of natural gas (methane). It is used for road transport, cooking, heating, refrigeration, air conditioning and in spray cans. It is a portable source of energy used for remote and leisure applications in the EU and in cooking and transport in developing countries. LPG is manufactured during the refining of crude oil (40%) or from natural gas during extraction (60%).
Liquefied natural gas (LNG) consists mainly of methane. Recent practice has been to liquefy the gas that is normally flared in oil fields in remote areas, but it can also be made from landfill gas when purified. LNG is about 1/614th the volume of natural gas at standard temperature and pressure, making it much more cost-efficient to transport over long distances, especially where pipelines do not exist. Similar to LPG, this portability is a major asset. LNG is used in transport and in heating and cooking as well as in industry and as a chemical feedstock.
The reliability of LPG/LNG cook stoves is generally considered high as the technology is mature and applied widely across the world (ENTTRANS, 2008). The same could be said about the supply chains for the LNG and LPG, although LNG transport could be vulnerable for security reasons. For example, IEA (2006) highlights supply problems due to hurricanes in North America. IEA (2006) also points out that the gas supply infrastructure is becoming more complex and more investment is required, in particular to increase transport skills and reduce investment costs. For importers there needs to be local distribution infrastructure development both for the fuel and for new stoves and stove conversions. Where LPG or LNG has been used in developing countries, as in the examples in China and Brazil below, then the governments in each case have subsidised the price of the gas and/or the price of conversions to burn LPG or LNG.
Although many developing countries already have access to LPG and LNG, the applicability of the technology to the rural poor is hampered by the required import facilities and distribution systems and complexities related to the poor quality of roads and relatively high per capita costs if the population density is low. The other main problem with LPG and LNG is that they can be expensive relative to other fuels and thus less attractive for the poor. In addition, the prices of LPG and LNG could be more volatile than the price of other fuels and feedstock for cooking. For example, in China, in the Fujian province, it was reported by Peoples Daily (2006) that people were switching from LNG stoves to electromagnetic stoves  as LNG prices had been increased by the government. In Guangzhou, in south China, a LNG price increase resulted in some residents turning to honeycomb coal briquets  for cooking. These possible price impacts could negatively affect the affordability of the technology and LNG/LPG fuels, in particular to rural area households (IEA, 2006).
LPG is seen by the IEA as the main means for moving away from unsustainable use of biomass for cooking: the target expressed in IEA (2006) is to reduce the use of biomass in cookstoves by 50% by stimulating 1.3 billion people to switch from biomass to LPG. The future market potential for LPG could thus be huge. However, other technologies and fuels (e.g., ethanol/methanol , Biomass gasification stoves , ICS, solar-based cooking) could serve the same purpose. LPG price increases could make LPG-based cooking less accessible for the poor, particularly in the rural areas. The scope for LPG/LNG for cooking is therefore not clear in developing countries, but it seems that it will be concentrated on the middle and high income groups in urban areas.
Existing gas stove burners can be easily adapted to burn LNG and LPG. Below are some examples of LNG/LPG applications in developing countries:
- In Brazil, 98% of the households have access to LPG through government policies to develop the required infrastructure in all urban and rural regions, in combination with an LPG subsidy. Recently, due increased LPG prices, residents have begun switching back to woodfuel (IEA, 2006).
- In 2001, 17.5% of Indian households (33.6 million households) used LPG as cooking fuel. Around three-quarter of these households were in urban areas; only 5.7% were rural households . Again, the LPG price is subsidised by the government. Increases in LPG prices are politically sensitive in India because of their effect on the middle classes, and recent increases in LPG prices have caused a move away from LPG. For instance, Climate Care  is supporting a project in the Punjab to promote the use of briquettes made from biomass crop residues in cook stove. These cookstoves are half the price of the existing LPG stoves, and the payback time from the savings made is 18 months.
- In China, 80,000 housing estates in Shenzhen have been converted to LNG. The price of natural gas was claimed to be lower and more stable than that of LPG and would not exceed 5 RMB/m3 (€0.43/m3). This is probably the result of the deal between China and Australia for the annual import of 3.7 million tons of LNG with a pricing mechanism that will ensure that the price is much lower than the current price for natural gas on the world market. However, the price of natural gas in Shenzhen would be higher than in Beijing and Shanghai due to the differences in the source and quality of gas, purchasing cost, construction and labour costs. In addition, the government supplies a subsidy for purchase of new equipment for LNG burning (Peoples Daily, 2006).
In developing countries the main benefits of LNG/LPG are in helping people to switch from unsustainable biomass use to a clean and safe cooking fuel. This provides enormous health benefits helping to avoid the 1.6million deaths/y from respiratory problems caused by smoke and other pollutants released by inefficient biomass burning in enclosed spaces (Warwick and Doig, 2004). It also releases women and children from the drudgery of collecting firewood and health problems associated with carrying heavy bundles long distances. There are also benefits for the local ecology and biodiversity. The UN Millennium project  recommends that globally the number of households using non-sustainable biomass for cooking should be halved by 2015.
LNG and LPG provide a ‘clean’ burn with almost complete combustion of the fuel so that there are only low pollutant emissions from NOx and very low particulate or other hydrocarbon emissions. There are no quantitative figures for the overall amounts of pollutants reduced by LNG and LPG, but considering the 2.5 billion people who currently rely on biomass-based fuels in the developing world , the potential for reductions in local smoke and volatile organic compound pollution is very large.
In order to get an overall perspective of the environmental benefits of LNG/LPG, a whole life cycle assessment is needed to consider the supply chains for the fuels. The supply chain for LNG requires pipelines for the gas, liquefaction plant, port facilities, and cryogenic tankers to transport the LNG where the gas is onshore. If the gas is offshore or where port facilities are not available, then floating liquefaction plants can be built. LNG plant design and LNG shipping are the other key links in the chain. The LNG is loaded directly onto ships from the production platform.
However, LPG is not commonly found in rural areas where biomass use tends to be highest and where the health effects of smoke are also highest. Nonetheless, it is used amongst middle or high income groups in urban areas of developing countries. The high initial cost of purchasing appliances and cylinders, the relatively complex technology, irregularity of supply and risk of explosion mean that it is not widely used in the majority of poorer areas of developing countries (IEA, 2006). The LPG supply chain is not practical for the poor as cylinders are usually exchanged at filling stations. Since there are not many of these in rural areas and since transport is poor, access to LPG is very difficult .
India has had an aggressive LPG promotion campaign for years and announced in February 2010 that there will be a program to provide free stoves to households below the poverty line  (Energy for Development, 2010).
The overall environmental impact of fuel switching to LNG/LPG can be positive or negative in terms of GHGs depending on the efficiency of combustion and sustainability of the fuel used. However, ICS and greater combustion efficiency generally would be expected to lead to larger reductions (IEA, 2006).
An interesting example of exploring the environmental effects of LNG is the KOGAS Environmental Load project , launched by the Government of Korea in 2002 to collect the environmental load information on a range of industrial chemicals. KOGAS, the Korean company for power production, also undertook a lifecycle analysis on the fuel cycle for the LNG it produced or imported compared to coal and oil for the production of 1GWh of electricity in order to conform to the government initiative and to maintain ISO 14001 certification standards. The results apply to the fuel cycle and give an indication of where problems may arise. These results show that LNG generates less CO2 as predicted from the low carbon/hydrogen ratio of the fuel. Production of CFCs is also much less than for other fuels. Similarly, acidification from sulphur dioxide and eutrophication from NOx levels are lowest for LNG. Finnegan (2004) shows that LPG extraction and refining contributes to SO2, NMHC, methane and NOx emissions, while transport of the LPG contributes to carbon monoxide and CO2 emissions. Reinaud (2005) gives figures for CO2 emissions from LPG refineries. Depending on the location of the refinery and the particular configuration the CO2 emissions associated with refining are 0.586-0.715 tCO2/t LPG.
For calculation of these GHG emission reductions, it is recommended to apply the approved methodology for thermal energy production with or without electricity  project (small scale activities) which has been developed under the Clean Development Mechanism of the UNFCCC Kyoto Protocol (CDM). This methodology helps to determine a baseline for GHG emissions in the absence of the project (i.e. business-as-usual circumstances), how emission reductions below this baseline can be calculated, and how these reductions can be monitored. General information about how to apply CDM methodologies for GHG accounting can be found at: http://cdm.unfccc.int/methodologies/PAmethodologies/approved.html .
LPG and LNG are already commercial activities. As mentioned above they are used in remote locations and for leisure in the EU.
The LPGas Rural Energy Challenge initiative  from the UNDP is engaged in activities to make LPG affordable. This can involve microfinance initiatives to make the equipment cost affordable over a period of time or fee for service operations. Even so, the cost of the fuel is still high for the poor. The recent Millenium Development Goals carbon initiative of the UNDP aims to provide finance in recognition of the need to tackle both poverty and mitigate climate change effects (UNDP, 2007).
Some examples of costs of using LPG/LNG in developing countries can be found above under Status of the technology and its future market potential .
Dell, R.M. and Rand, D.A.J., 2004. Clean Energy, RSC Clean Technology Monographs.
Energy for Development, 2010. Cooking with LPG: Climate and Poverty Issues . Available at: http://www.energyfordevelopment.com/2010/02/lpg-cooking-poverty-climate-change.html 
ENTTRANS, 2008. Sustainable, Low-Carbon Technologies for Potential Use under the CDM – A description of their environmental, economic, and energy aspects , Groningen, the Netherlands.
Finnegan, S., 2004. LCA of alternative fuels. Available at: http://www.ecotravel.org.uk/sf_work.html 
IEA, 2006. World Energy Outlook 2006, OECD/IEA, Paris, France.
Peoples Daily, 2006, Issue of 12-01-2006. Available at: http://english.people.com.cn/200601/12/eng20060112_234940.html 
Reinaud, J., 2005. The European Refinery Industry under the EU Emissions Trading scheme, IEA information paper.
UNDP, 2007, MDG Carbon Facility: Leveraging Carbon Finance for Sustainable Development. Available at: http://www.mdgcarbonfacility.org/ 
Warwick, H. and Doig, A., 2004. Smoke: the Killer in the Kitchen, Indoor Air Pollution in Developing Countries, ITDG Publishing, London, the UK.