For the first time in human history more than half the Earth’s population have migrated to live in towns and cities and complete global urbanisation seems to be inevitable.

Forty years ago the population of only three cities exceeded 10 million, whereas now there are 32 cities of this size and three of these are home to over 20 million each.

United Nations Population Division estimates predict that the rate of global urbanisation will continue to accelerate to approach 60% by 2030 and 70% by mid-century. This trend will have major impact on the demand for energy, particularly in the developing countries of Africa and Asia.

The importance of energy security
Interruptions in supplying the energy demand of urban populations have potentially greater impact than mere frustration and inconvenience; they can threaten economic and physical survival.

Public transport, road traffic control, lighting, heat, air-conditioning and ventilation in retail malls, offices, hotels, apartments and public facilities all depend on continuous energy supply and power outages result in chaos.

The failure of health services, emergency services or the maintenance of law and order due to energy scarcity could easily have life or death consequences. Industrial and commercial activities from manufacturing to service delivery all depend on continuous energy supply for their efficient operation.

Sources of energy & delivery factors
The primary energy resources listed in most discussions are: coal, crude oil, natural gas, nuclear fission, hydro-power and other renewables. Considerable differences exist between these six options in terms of distribution and availability, ease of production, storage and transportation.

Coal mining has a long history of accidents and explosions and is probably considered the most dangerous to extract. The magnitude of pollution risk from the spillage of crude oil was recently demonstrated on a grand scale in the Gulf of Mexico.

Despite these difficulties, both coal and oil are stored and transported in vast quantities across the oceans and continents using bulk carriers, tankers, conveyors and pipelines. Apart from their ever increasing size and capacity, these may be described as conventional. Stocks can be accumulated in the event that production should exceed demand or stockpiled in the anticipation of interrupted supply.

Historically it was coal that fuelled the industrial revolution and it continued to be the world’s primary energy resource until the mid 1960s when it was overtaken by oil. Despite the obvious convenience and reduction in pollution associated with oil burners, there was some reluctance to convert because the future supplies of oil seemed uncertain.

As the oil industry grew and extraction technology developed, the price of oil fell and it was the promise of cost savings that convinced the majority of consumers to switch. Ironically, the price of crude oil is still influenced by fears of depletion, referred to as ‘Peak Oil’.

Natural gas reserves were first discovered during the process of exploring for deposits of crude oil and this low-grade fuel gas is still often flared to atmosphere as a waste product. The potential of natural gas to contribute very significantly to the energy mix was only realised when the vast size of untapped gas reserves became apparent. The low energy density of natural gas, consisting as it normally does of mainly methane with impurities of carbon dioxide and occasional small percentages of helium, has serious cost implications for both its storage and its distribution.

The trade in natural gas as a primary energy source was limited to the range of long-distance pipelines, until the development of purpose designed carrier ships that deliver this cryogenic liquefied natural gas (LNG) across the oceans and around the globe. The fact that LNG stores only 60% of the energy stored in an equivalent volume of crude oil means that the LNG trade is fundamentally more risky. The expansion of LNG capacity requires major capital investment in plant and carriers and the liquefaction process is energy intensive.

LNG, like other cryogenic liquids, has a limited ‘shelf-life’ in storage because even the most sophisticated thermal insulation systems cannot prevent the ingress of heat which causes vaporisation and pressure build-up. This implies that stocks cannot be accumulated without expensive losses and excess production will quickly precipitate a fall in spot market prices. Long-term high volume contracts are a pre-requisite to approval of new liquefaction projects.

Greenhouse gases
As a brief aside, we should at this point look at the other aspects of the conventional fuels that we’re so familiar with. After all, this wouldn’t be the ‘green’ issue without some reference to greenhouse gases (GHGs) and any of the associated factors.

Two factors related to the accumulation of greenhouse gases affect Earth’s climate because they interact with the incoming radiation. The first factor is the degree to which a gas reflects heat back into space, and the second factor is how long that gas remains in the atmosphere. Although the products of combustion do include both water vapour and CO2, human activity contributes only slightly to greenhouse gas concentrations through farming, manufacturing, power generation, and transportation.

Many environmentalists do not consider water vapour to be a greenhouse gas, despite its reflective qualities and relative abundance. Some argue that because water vapour is naturally abundant, our influence estimated at 0.28% is comparatively negligible. Even though water vapour is responsible for nearly 95% of the greenhouse effect, others argue that because it is part of the natural weather cycle it can’t be considered and on this basis the human contribution rises to 5.53%.

If we disregard the main and natural cause of global warming and only focus on the causes related to the combustion of fossil fuels, then three major greenhouse gases emerge. Top of the list is CO2, followed by methane (CH4) and finally nitrous oxide (N2O).

Fossil fuels are also known as hydrocarbons because their molecules are made up of carbon and hydrogen in many different ratios and configurations. These fuels have largely replaced the traditional biomass as industrialisation has spread around the globe. The final products of complete combustion are carbon dioxide and water vapour, both of which are natural substances in the terrestrial environment and both behave as green-house gases and are minor constituents of the atmosphere.

Incomplete combustion, high temperature combustion and the presence of elements like sulphur in hydrocarbon fuels result in the emission of toxic gases including nitrogen oxides, carbon monoxide and sulphur dioxide.

Another powerful greenhouse gas is CH4 which occurs naturally in huge underground deposits, often together with crude oil deposits, and is the major component of natural gas. The decomposition of landfill waste and digestion of sewage in wastewater treatment plants and cattle farms are all sources of CH4 – some of which is recovered as useful energy.

Balancing act
It is feared that the increasing concentration of greenhouse gases will shift the fine balance between heat reflected and heat retained, causing ambient temperatures to rise.

An increase in atmospheric temperature also affects the amount of water frozen at the poles. If the temperature in the atmosphere increases and the polar ice melts, it could affect both human and marine life drastically:
* World temperatures could rise by between 1.1 and 6.4°C during the 21st century;

* Sea levels will probably rise by 18 to 59cm;

* There will be more frequent warm spells, heat waves, and heavy rainfall;

* There an increase in droughts, tropical cyclones, and extreme high tides.

This environmental balancing act brings us to the subject of carbon credits. A carbon credit is like a form of environmental currency. One carbon credit is equal to one tonne of CO2 emission. Companies that reduce their CO2 emissions have the opportunity to earn carbon credits that they can trade to other industries. This incentive system is intended to reward environmentally conscious industries financially while taxing harmful industries for their neglect.

Though for the most part this system does show promise, it does have the potential to simply pass the problem on to somebody else. The emissions from natural sources beyond our control are so large that even the expensive measures designed to limit human emissions may have a very small, and perhaps undetectable, effect on global climate.

Oxygen applications that optimise fuel efficiency can reduce emissions and result in higher concentrations of CO2 in the waste gas – thus facilitating its capture for storage. Many other gas applications are used by diverse industries to reduce emissions of harmful emissions and greenhouse gases. Industrial gases such as CO2 are normally sourced from the waste gas streams emitted by existing combustion processes.

Final energy consumption by fuel
Returning to the energy diversification debate, and liquid fuels and primarily oil are expected to dominate the final consumption of energy, but electricity consumption is expected to continue growing most rapidly.

The global use of electricity grew 54% between 1990 and 2005 according to the IEA. Despite the rising trend in price, natural gas is expected to remain an important primary fuel for electricity generation. Gas-fired combined cycle plants are recognised for high fuel efficiency, are less capital intensive and constructed more rapidly than plants fuelled by coal, nuclear or renewable energy sources.

The adoption of natural gas is also favoured by the ‘green movement,’ because it is characterised by significantly lower emissions of sulphur dioxide, carbon dioxide and particulate matter than oil or coal.

High oil prices have motivated rapid growth in the number of gas-fired generating plants and natural gas is expected to be the fastest-growing primary energy source through until 2020, when rising extraction costs will retard the growth rate in favour of alternatives like renewable energy or nuclear power. Unless policies are implemented to curb their use, coal-fired generation plants are likely to gain popularity especially in those countries with large accessible reserves and growing industrial demand; including China and India.

Contrary to earlier forecasts, it is unlikely that natural gas consumption will oust coal as the dominant power generating energy source.

Oil products provide the largest share of final energy globally: 35% in 2010, driven by their use in transport. The substitution of renewables and natural gas is expected to erode this down to 30% by 2035. The fastest growth will be seen in renewable energy technologies, but they are unlikely to exceed 14% by 2035. Although the amount of primary energy derived from nuclear fission will nearly double, it will peak at only 6% in 2035.

Does hydrogen promise a solution?
It is significant to note that hydrogen is not mentioned in the energy outlook publications released by the EIA, IEA or BP.
The technical breakthrough that will enable the production of low cost hydrogen from water is yet to be announced.

Hydrogen, being highly reactive, only occurs naturally in stable compounds and all known separation processes are too costly for this alternative energy to compete with conventional liquid fuels.

In the early 2000s several governments pledged support for the development of infrastructure to support a hydrogen economy starting with passenger vehicles. At the close of the decade nothing like a commercial hydrogen car market exists yet and support has waned considerably, especially in the US and Canada. Stakeholders there in the hydrogen economy have shifted their near-term focus away from transport applications, to stand-alone products like standby and portable power supply units.

Energy Secretary and Nobel prize-winning physicist Steven Chu explained, “...the Department is reducing funding for the hydrogen technology programme by more than 41%, or almost $70m, in order to focus on technologies deployable at large scale in the near term.”

Car manufacturers developed Hydrogen Fuel Cell (HFC) technology and offered hydrogen-powered test-models in several countries around the world, but the motoring public has not received these vehicles with sufficient enthusiasm. In terms of infrastructure or vehicles on the road, little progress can be claimed despite the investment of $2bn globally over a 15-year period, especially when compared with the advances made by electric and hybrid drive cars.

Transportation planners and policymakers abandoned the ‘hydrogen highway’ programme envisioned by US state of California’s Governor, Arnold Schwarzenegger, in 2003 and decided instead on a more realistic pilot programme – to create a cluster of 10-20 stations in a specific region close to where the vehicles reside.

Several member countries of the International Partnership for Hydrogen and Fuel Cells in the Economy (IPHE) still maintain the vision and have announced continued investment:

* Germany is continuing to fund HFC programs, some of which go to 2013;

* Japan is continuing to fund HFC programmes to 2014;

* South Korea has aggressive plans for commercialisation and export of HFC technology that enjoy strong government support.

Up to 10 Japanese energy companies, including automakers and gas suppliers, have announced that they will put up 100 hydrogen fuelling stations in Japan by 2015.

Toyota’s Executive Vice-President for Research and Product Development, Takeshi Uchiyamada, recently announced that by 2015 they intend to be selling hydrogen cars for around $50,000 – which is half of what it costs to build them now.