Energy Resources

Construction of a scenario for energy supply must be consistent with energy resource endowments and various practical constrains on the recovery of these resources [51]. The renewable energy resources have been discussed in previous sections.

Conventional fuels
By making efficient use of energy and expanding the use of renewable technologies, the world can expect to have adequate supplies of fossil fuels well into the 21st century.

Oil production outside the Middle East would decline slowly, so that one third of the estimated ultimately recoverable resources will remain in the ground in 2050. To meet the demand for liquid fuel that cannot be met by renewables, oil production is assumed to increased in the Middle East. Total world conventional oil resources would decline from about 9 900 exajoules in 1988 to 4300 exajoules in 2050.

Although remaining, conventional natural-gas resources are comparable to those for conventional oil, gas is presently produced globally at just half the rate for oil. With adequate investment in pipelines and other infrastructure components, gas could be a major energy source for many years. In the decades ahead, substantial increases in gas production are feasible in all regions of the world except OECD, Europe and USA. There, where resources are more limited, production would decline slowly, so one-third of these regions’ gas resources will remain in 2050. In aggregate, gas production outside the Middle East would increase slowly, from 62 exajoules per year in 1985 to 75 exajoules per year in 2050. But in the Middle East, where gas reserves are enormous and largely unexploited, production would expand more than 12-fold, to 33 exajoules per year in 2050. Globally, about half the conventional gas resources would remain in 2050.

It is expected that in the decades ahead, the world oil price would rise only modestly and the price of natural gas would approach the oil price (which implies that the gas price paid by electric utilities would roughly double). There are two reasons for expecting a modest energy price increase: first, overall demand for fuels would grow comparatively slowly between 1985 and 2050 because of assumed increases in the efficiency of energy use; and second, renewable fuels could probably be produced at costs that would make them competitive with petroleum at prices not much higher than at present.

Electricity is the energy carrier of choice for the modern economies since growth in electricity has outpaced growth in the demand for fuels. This trend is projected to continue by the IPCC. It is expected that the average per-capita demand for electricity will increase by 70% between 1985 and 2050, while per capita direct use of fuels will decline by more than 30%. Demand is expected to rise especially sharply in developing countries, which are projected to experience almost a five-fold increase in per-capita electricity consumption. Overall, world demand for electricity would increase some 265% by 2050 in the accelerated policy scenario of the IPCC, which is equivalent to adding more than 50 large (1000MW) plants each year.

Technical developments of renewable and other technologies will contribute to enrich the set of available electric-generating equipment. Advanced gas turbines, originally developed for aircraft engines and now applied for power generation, are a prominent example. With natural gas firing, such turbines have achieved systems efficiencies of 45% for commercial units (compared with 35% of conventional steam-electric power units), and efficiencies greater than 2000 will likely achieve 50%. Therefore, advanced gas turbine and fuel-cell technologies powered with natural gas are likely to achieve efficiencies ranging from 55-60%.

Natural gas
Natural gas-fired generating technologies, especially those based on gas turbines, are well suited to power systems that incorporate large amounts of intermittent renewables. The technologies are economical in comparatively small (50-100MW) sizes. Large gas turbine, steam combined-cycle plants are also commercially available.

Because gas turbines have low capital costs, they have been long used by utilities for "peaking service". That is, to meet infrequent demand peaks, such us those that occur only a few hours each year. But because they have been relatively inefficient, gas turbines have not been operated during extended periods. This situation is changing rapidly, however, with the emergence of a new generation of highly efficient gas turbines. Power systems based on these turbines and fuelled with natural gas compete with coal-fired power plants in many areas even if the gas price doubles. Moreover, because these systems can be designed to produce relatively low emissions, their development can help abate air pollution problems. Not surprisingly, utility interest in these systems is growing rapidly.

Competitively priced advanced gas turbine systems are available at relatively small scales. These smaller units are attractive because they can be installed quickly and located at dispersed sites reducing the risks inherent in building large centralised plants when demand is uncertain. In addition, they can be started rapidly to meet fluctuating demand. This feature makes advanced gas turbine power systems an attractive complement to large intermittent electric generators on a utility system.

Coal is the dominant fuel for electricity production in many parts of the world. Technical advances during the past four decades have led to sophisticated large-scale steam-electric plants that are now typically 35% efficient. However, the performance of such systems may be approaching practical limits, and costs have increased as a result of increasingly stringent environmental regulations. New technologies are needed to achieve further efficiency improvements and cost reductions. The most promising new technology is an integrated gasifier/gas turbine power system. In this system coal is gasified at high temperatures, and the hot gas is used directly as fuel for a gas turbine power-generating cycle. This technology creates much less air pollution than steam-electric technology and is more energy-efficient.

It is difficult to know whether coal or nuclear power will be the least costly during the next few decades. Technical advances are expected in both areas, and the cost of both will be heavily influenced by regulations.
The nuclear power industry is in trouble because of rapidly rising costs, the unsolvable nuclear waste issue, and serious reactor safety issues, all of which contribute to poor public opinion. But, the industry hopes for a comeback fueled by efforts to sway public opinion with multi-million dollar advertising campaigns. In spite of the money being spent by the industry, the energy trends report predicts that nuclear power will no longer contribute to our nation’s energy mix by the year 2010.