Electricity is the foundation of modern societies, yet more than 1.6 billion people remain without access to the electrical grid. A majority of this population lives in South Asia and sub-Saharan Africa. Despite global economic expansion and advances in energy technologies, roughly 1.4 billion people (or 18% of the world’s population) will still be without power by 2030 unless major governmental incentives are put into place (Dorian et al., 2006).

The world average annual electricity consumption is between 2 and 4 TW. The cost of fossil- derived electricity is now in the range of US$ 0.02-0.05/kW/hr, including storage and distribution costs (Lewis & Nocera, 2006). For comparison, the options of non-biological electricity generation are as follows. (i) The light-water reactors that make up most of the world’s nuclear capacity produce electricity at costs of US$ 0.025-0.07/kW/; however, there is no consensus as to the solution to the problem of how to deal with the nuclear wastes that have been generated in nuclear power plants over the past 50 years (Schiermeier et al., 2008). (ii) Hydroelectric energy sources have a generating capacity of 800 GW (i. e., 10 times more power than geothermal, solar and wind power sources combined) and currently supply approximately one-fifth of the electricity consumed worldwide. Annual operating costs are US$ 0.03-0.10/kW/h, which makes such sources competitive with coal and gas. Because only approximately 30% of worldwide hydroelectric capacity is currently used, energy from these sources can still be tripled (Schiermeier et al., 2008). (iii) Wind turbines can produce 1,500 kW at US$ 0.05-0.09/kW/h making wind competitive with coal; wind power could provide up to 20% of the electricity in the grid. The EU should be able to meet 25% of its current electricity needs by developing wind power in less than 5% of the North Sea and is heavily investing in that option. (iv) Exploitation and resulting use of the best geothermal sites is estimated to cost approximately US$ 0.05/kW/h. Thus, 70 GW of the global heat flux is seen as exploitable. However, because of the great deal of investment required, exploitation of geothermal power lies outside of current priorities except in regions with significant volcanic activity (Schiermeier et al., 2008). (iv) Commercial photo­voltaic (PV) electricity costs US$ 0.25-0.30/kW/h, which is still 10 times more than the current price of electricity on the grid.

The possibility for use of current PV technology is limited to 31% by theoretical considerations. A conversion efficiency of >31% is possible if photons with high energies are converted to electricity rather than to heat. With use of such technology, the conversion efficiency could be >60% (Lewis, 2007). The absence of a cost-effective storage method for solar electricity is also a major problem. Currently, the cheapest method of solar-energy capture, conversion, and storage is solar thermal technology, which can cost as little as US$ 0.10-0.15/kW/h for electricity production. This requires the focusing of the energy in sunlight for syngas or synfuel synthesis (Lewis & Nocera, 2006) or its thermal capture by heat-transfer fluids that are able to sustain high temperatures (>427 °С) and resulting electricity generation through steam production (see in Shinnar & Citro, 2006). Solar power is among the most promising carbon-free technologies available today (Schiermeier et al., 2008). The earth receives approximately 100,000 TW of solar energy each year. There are areas in the Sahara Desert, the Gobi Desert in central Asia, the Atacama in Peru and the Great Basin in the US that are suitable for the conversion of solar energy to electricity. The total world energy needs could be fed using solar energy captured in less than a tenth of the area of the Sahara. Residential and commercial roof surfaces are already being used in several countries to allow the people to sell their own PV electricity to the grid (and in this way saving substantial annual costs). This elegant strategy could be extended to other systems of energy production.

The capital costs of biomass are similar to those of fossil fuel plants. Power costs can be as little as US$ 0.02/kW/h when biomass is burned with coal in a conventional power plant. Costs increase to US$ 0.04-0.09/kW/h for a co-generation plant, but the recovery and use of the waste heat makes the process much more efficient. The biggest problem for new biomass power plants is finding a reliable and concentrated feedstock that is available locally. Biomass production is limited by land-surface availability, the efficiency of photosynthesis, and the water supply. Biomass potential is estimated at ~5 TW (Schiermeier et al., 2008). Photosynthesis is relatively inefficient if one considers that in switchgrass (one of the fastest — growing crops), energy is stored in biomass at an average rate of <1 W/m2/ yr. Given that the average insolation produces 200-300 W/ m2, the average annual energy conversion and storage efficiency of the fastest growing crops is only <0.5% (Lewis 2007; Lewis & Nocera,

2006) . However, photosynthetic efficiency can be improved by genetic engineering (Ragauskas et al., 2006). Another potential problem with biomass production is that it could result in an increase of water consumption of two to three orders of magnitude. This is an important consideration because basic human necessities and power generation are increasingly competing for water resources (King et al., 2008).

The potential availability of wind (Pryor & Barthelmie, 2010), solar and biomass energy varies over time and location. This variation is not only caused by the individual characteristics of each resource (e. g., wind and solar regimes, soils), but also by geographic (land use and land cover), techno-economic (scale and labor costs) and institutional (policy regimes and legislation) factors (de Vries et al., 2007). The regional potential in energy units/year must be integrated over the geographical units that belong to a particular region. The model from de Vries et al. (2007) showed the following: (i) electricity from solar energy is typically available from Northern Africa, South Africa, the Middle East, India, and Australia; (ii) wind is concentrated in temperate zones such as Chile, Scandinavia, Canada, and the USA; (iii) biomass can be produced on vast tracts of abandoned agricultural land typically found in the USA, Europe, the Former Soviet Union (FSU), Brazil, China and on grasslands and savannas in other locations. In many areas of India, China, Central America, South Africa and equatorial Africa, these energy sources are available at costs of below US$ 0.1/kW/h and are found in areas where there is already a large demand for electricity (or there will be such demand in the near future). A combination of electricity from wind, biomass and/or solar sources (Eugenia Corria et al., 2006) may yield economies-of-scale in transport and storage systems. Regions with high ratios of solar-wind-biomass potential to current demand for electricity include Canada (mainly wind), African regions (solar-PV and wind), the FSU (wind and biomass), the Middle East (solar-PV) and Oceania (all sources). In other region (such as Southeast Asia and Japan), the solar-wind-biomass supply is significantly lower than the demand for electricity. Ratios of around one are found in Europe and South Asia. The potentials just described depend on many parameters, and their achievement will depend on future land-use policies (de Vries et al., 2007; Miles & Kapos, 2008).

2. Management and sustainability

Adam Smith’s notion that by pursuing his own interest a man "frequently promotes that of society more effectively than when he really intends to promote it" and Karl Marx’s picture of a society in which "the free development of each is the condition for the free development of all" are both limited by one obvious constraint. The world is finite. This means that when one group of people pursues its own interests, it damages the interests of others (Vertes et al., 2006). The model of Western economies was established using this logic. The theoretical framework of this philosophy is a mathematical model that is based on energy-conservation equations formulated by von Helmholtz in 1847, in which physical variables were arbitrarily substituted by economic ones. The consequences of this model are as follows: (i) the market is a closed circular flux between production and consumption, without inflows or outflows; (ii) natural resources are located in a domain that is separate from that of the closed market system; (iii) the costs of environmental destruction because of economic activities must be considered as unrelated to the closed market system (or at least they cannot be included in the price-formation processes of that system); (iv) the natural resources that are used by the market system are endless and those that are limited in quantity can be substituted by others that are endless; and (v) biophysical limits to the increase of the market system simply do not exist (Nadeau, 2006). This model is obsolete and is based on hypotheses that have no grounding in scientific bases. Sustainable economic solutions to global warming and environmental destruction are impossible to establish under the logic of this model.

As a consequence, the US alone has reached a level of oil consumption in the transportation sector that approaches 14 Mbl/ day and corresponds to a release of 0.53 gigatons of carbon per year (Gt C/yr). The current global release of carbon from all fossil fuel usage is estimated to be at 7 Gt C/ yr and is expected to rise to ~14 Gt C/yr by 2050 (Agrawal et al.,

2007) . It has been estimated that global energy consumption could reach 30-60 TW by 2050. With world population expected to reach 8 billion by 2030, the scale-up in energy use that is needed to maintain economic growth is critical. China, with 1.3 billion people and a fast­growing economy, has overtaken Japan to become the second-largest oil consumer behind the US. The Asian giant is currently the largest producer and consumer of coal (Tollefson,

2008) and has announced the construction of 24-32 new nuclear reactors by 2020 (Dorian et al., 2006). If current trends continue, the world will need to spend an estimated $16 trillion over the next three decades to maintain and expand its energy supply. Generation, transmission, and distribution of electricity will absorb almost two-thirds of this investment, whereas capital expenditures in the oil and gas sectors will amount to almost 20% of global energy investment.

Experts believe that peak of world oil production should not occur before at least 30-40 years from now. To put global oil needs into perspective, demand for oil is projected to rise from nearly 80 Mbl/day today to over 120 Mbl/day by 2030. The OPEC nations are currently operating at near full capacity, which caused oil prices to reach US$ 120/bl in August 2008. Clearly, the world must find more efficient ways to manage energy. Some argue that the supplies of oil needed to satisfy the growing world demand will become available because of a combination of price and technology incentives (Rafaj & Kypreos, 2007). As oil prices continue to rise because of increasing difficulties in reaching remaining oil resources, other energy forms will appear (Herrera, 2006). A transition from oil to renewable energy should occur at some point before the world runs out of oil resources (Dorian et al., 2006). Renewable energy sources, including solar, wind, and geothermal, but excluding biofuels, currently provide only 3% of world energy demand (Dorian et al., 2006). Solutions that use these energy sources should be increased worldwide and should be connected to the electricity grid.

Renewable biodiesel from palm oil and bioethanol from sugarcane are currently the two leaders of plant bioenergy production per hectare. They are being grown in increasing amounts; however, continuous increases in their production are not sustainable and will not resolve the enormously increasing demands for energy. Palm oil yields ~5,000 l/ha. In Brazil, the best bioethanol yields from sugarcane are 7,500 l/ha. Most of the energy needed for growing the sugarcane and converting it to ethanol is gained from burning its wastes (e. g., bagasse). For every unit of fossil energy that is consumed by producing sugarcane ethanol, ~8 units of energy are recovered (Bourne, 2007). The rates of energy recovery from other biofuel crops are usually less than 5. Biofuel crops from the EU are much less productive than palm oil and sugarcane; therefore, B5 enforcement would require that ~13% of the EU25 arable land be dedicated to biofuel production. This is hardly sustainable (the present situation is ~5 times less).

Regarding environmental impact, ethanol from corn (for example) contains costs that stem from the copious amounts of nitrogen fertilizer used and the extensive topsoil erosion associated with cultivation. Every year, pesticides, herbicides and fertilizers run off the corn fields and bleed into groundwater. River contamination promotes eutrophication, algal blooms and ‘dead zones’. In addition, ethanol importation by industrialized nations could lead to increased ecological destruction in developing countries as indigenous natural habitats are cleared for energy crops (Gui et al., 2008; Marris, 2006; Thomas 2007).

The general feeling is that first-generation biofuels are already reaching saturation because of the limited availability of arable lands. Brazil has additional lands available for sugarcane and physic nut production, whereas India is promoting physic nut cultivation on its extensive wastelands. However, the development of these fuels has already been a success because they have demonstrated that motor technology running on ethanol or biodiesel is feasible and can (at least) be used to power public transport.

Fortunately, second-generation biofuels from biomass offer additional opportunities. The cost of feedstock is lower for lignocellulose as compared to the agricultural crops that now contribute up to 70% of the total production costs for first-generation bioethanol. Even if they are more expensive now, synfuel from biomass sources (such as poplar, willow, and reed grass) could have higher cost effectiveness in the near future than does fuel from sugar beets, wheat and rapeseed sources (Wesseler, 2007; Styles & Jones, 2008).

Biomass fuels will be another opportunity for the EU to meet its target of energy production from renewable sources. However, this goal has not been met by 2010 as was initially expected (Fischer et al., 2010; Havlik et al., 2010). The European CO2 emissions-trading system of carbon credits seems to be much more cost effective than its biodiesel program because it allows for the purchase of units of CO2 sequestration in tropical climates that have much higher rates of fixation than do temperate ones (Frondel & Peters, 2007). Third-generation biofuels have also entered the race for fuel renewability. In terms of total dry matter, sugarcane typically yields ~75 t biomass per hectare, whereas microalgae are able to produce two times more biomass per hectare (Brennan & Owende, 2010; Chisti, 2007, 2008). Considering a productivity of 150 t/ha and an average dry-weight oil content of 30%, the oil yield per hectare would be ~123 m3 over 90% of the year (i. e., 98.4 m3/ha). If 0.53 Gm3 of biodiesel are needed in the US to power transport vehicles, microalgae should be grown over an area of ~5.4 Mha (3% of the US). Producing algal biomass in a 100 t/yr facility has been estimated to cost approximately US$ 3,000/ton. The feasibility of oil extraction for microalgal biomass has been demonstrated (Belarbi et al., 2000; Sanchez Miron et al., 2003) and the majority of algal biomass residues from oil extraction can be recycled by anaerobic digestion to produce biogas.

Impediments to large-scale culture of microalgae are mainly economic and are tied to the investment requirements for the algae cultivation. One solution would be to increase the oil productivity by genetic and metabolic engineering (Leon-Banares et al., 2004; Mathews & Wang, 2009). One may expect the expansion of algal technology via CO2 filtration because power plants can incorporate this technology immediately into their management systems. This technology is expected to spread slowly with the accumulation of experience.

Nearly half of the world’s oil consumption is dedicated to the transportation sector, which also accounts for 32% of GHG emissions. The overall efficiency of energy conversion to work in the transportation segment is lower than it is in large-scale power plants and the goal is to increase it from the current level of 15-35 to 60-80% (Song, 2006).

Unfortunately, advanced transportation technologies (such as hydrogen fuel cell vehicles and alternative fuels including gas-to-liquids, coal-to-liquids, and biodiesels) are not likely to significantly penetrate the conventional transportation fuel market before 2030 (except on a regional basis). The growth in oil consumption for transportation use in the coming decades may be slowed by the adoption of fourth-generation technologies such as hybrids and fuel cell cars. However, the necessary technological breakthroughs will not occur without unprecedented policy actions worldwide to promote the use and inclusion of these technologies in everyday life (Doniger et al., 2006; Haug et al., 2011; Michel 2009). Currently, there are approximately half a million hybrids and 30 million advanced clean-diesel engines globally. The use of hybrid cars is growing in the US and Japan, whereas advanced clean — diesel motors are mostly concentrated in Europe (Dorian et al., 2006).

Actually, auto-mobility is a self-organizing and non-linear system that presupposes and calls into existence an assemblage of cars, drivers, roads, fuel supplies, and other objects and technologies. Modern social life has become interconnected with auto-mobility. However, this mode of mobility is neither socially necessary nor inevitable (Urry, 2008). One billion cars were produced during the last century. World automobile travel is predicted to triple between 1990 and 2050 (Hawken et al., 2002). Today, world citizens move 23 Gkm annually. Auto-mobility forces people to contend with the temporal and spatial constraints that it itself generates (Mills et al., 2010). Fortunately, some 35-year-old projects have begun to be finally implemented (i. e., the integration of car and bicycle rentals into public transportation systems, such as occurs in some European cities). A post-car future will involve changes in lifestyles, city architecture, thinking and social practices. Increased active transport (e. g., walking and bicycling) will help to achieve substantial reductions in emissions while improving public health. Cities require safe and pleasant environments for active transport as well as easy accessibility of public transport. Adverse health effects because of transportation include traffic injuries, physical inactivity (the cost of obesity in the USA is estimated to be around US$ 139 bn/yr), urban air pollution, energy-related conflicts, and environmental degradation. For instance, urban air pollution accounts for 750,000 deaths each year, of which 530,000 are in Asia (Woodcock et al., 2007). Because of limited energy resources, it has been argued that the world will be required to move toward virtual travel (such as internet surfing, virtual sensorial traveling, and video conferences) to replace physical travel as much as possible (Moriarty & Honnery, 2007).

In reality, the situation outlined above is the result of consideration of humanity only within social contexts and without the necessary environmental perspective (Thomas, 2007). The concept of environmental crime barely operational; if it exists at all, it is very recent and is not generally applied. Logical human societies should take into account the amount of land that human beings and wildlife actually need to reasonably sustain themselves. Not doing this will lead to increasing worldwide destruction (Urry, 2008) and will threaten the future of humanity. These considerations led to the formulation of the Gaia principle (Lovelock & Margulis, 1974). This principle states that one should consider the planet Earth as a whole, with the consequence that the destruction of one ecosystem can affect all of the others. Concern for the value of ecosystems is recent (Costanza et al., 1997). Society has only begun to address human integration with the environment because of the threat of global warming and its potentially disastrous effects (Stern, 2006). A discussion of the economic accounting for ecosystem services from the perspective of sustainable development has also been proposed (Maler et al., 2008).

The concept of "willingness-to-pay" (WTP) has also been recently introduced. This concept allows for the monetary measurement of individual preference to avoid a negative impact. It aims to estimate the need for improved environmental quality. WTP measures how much individuals are ready to pay to improve their quality of life or that of other people. The sum of the WTP of all individuals gives the value that a group of individuals are ready to pay to maintain their environment in an unaffected state. For example, the pathways of polluting substances are followed from their release sources to the points of damage occurrence with associated "external" costs of reparation. Taking external costs into account in the full cost of energy production leads to the estimation of the "real" cost of an activity and supplies an efficient policy instrument for reducing the negative impacts of energy use (Nast et al., 2007). The approach of merging production costs with external costs into a total specific cost serves as a comparative indicator for the evaluation of the economic-environmental performance of energy options and technologies (Rafaj & Kypreos, 2007). The scenarios proposed under this new cost-accounting strategy reveal the possibilities for the diffusion of advanced technologies and fuel switching into the electricity production system. Following this model, renewable energies increase their competitiveness and the dependency of the electricity sector on fossil fuels is decreased considerably. Additionally, emissions of SO2 and NOx decrease by 70-85% by 2030. Although the analysis indicates that advanced technologies with emission controls and carbon sequestration will undergo significant cost reduction and will become competitive in the long run, policies supporting these technologies are a prerequisite to their establishment in electricity markets (especially during their initial period of market penetration). This model refers to policy measures for the stimulation of technological progress via investments in research and development that assist carbon-free technologies to progress along their necessary learning curves (Haug et al., 2011; Rafaj & Kypreos, 2007).

3. Conclusions

The time has come for the integration of the technological and social sciences to find a route to environmental and economic sustainability on earth. If such a solution is not reached, economic growth will occur at the cost of the human population size (Urry, 2008). Fortunately, because of the continuous increase in the price of fossil fuel, investigations into sources of renewable energy have become economically viable. It is now clear that technologies for renewable energies have reached a pivotal stage such that there is no turning back. There are at least 5 regional blocks (the USA, the EU, China, Brazil, and India) that are interested in decreasing their dependence on fossil fuels. It does not appear to be in anyone’s interest to shut this process down by mean of aggressive oil price cutting and market dumping. In fact, biotechnology is intimately bound to agricultural processes that are also supported by governments because of geostrategic issues. In addition, climate change is becoming obvious and will soon overcome particular interests to become a general concern of humanity.

Biofuels and sources of bioenergy will pass through a rapid succession of technological improvements and developments before they arrive in their final forms. It is expected that bioethanol from sweet crops will be surpassed by bioethanol from biomass. Synfuel from biomass and solar energy should also progressively replace plant biodiesel. Biotechnology is expected to increase its participation in microdiesel fuel production, in genetic engineering of plants and microorganisms and in the contribution of enzymes to nanotechnology.

The integration of renewable energies into the electricity grid is just beginning, but is already progressing rapidly. It is expected to make a significant contribution; however, it should be accompanied by policies of energy management and urbanization to avoid unnecessary energy waste that could negate the benefits of technological breakthroughs and developments. New concepts (such as willingness-to-pay, carbon credits and external costs) are now being taken into account in the calculation of energy life cycles. This toolbox will expand with increasing government regulations and should include fundamental concepts such as "biodiversity credits" and the definition of a "minimal territorial unit" for living entities to warrant sustainability of wildlife and humanity. Biodiversity is a source of nanostructures and nanomachines. It should not be destroyed without consideration when we are aware that it required three billions years to develop and that humanity is just beginning to investigate it.

As a result of energy saving requirements, the cars of the near future will run on combinations of fuel combustion and electricity. Such options can reduce fossil fuel consumption and greenhouse gas emissions by 30 to 50%, with no gross vehicle modifications required. In addition, they will allow for connection to the electricity grid for additional cost saving on electricity consumption. These so-called plug-in hybrids will likely travel three to four times farther per kW/h than other vehicles. Ideally, these advanced hybrids will also be flexible and capable of running on bio/fossil blends and gas (Romm,

2006) .

At some point during the first half of this century, a transition from fossil fuels to a non­carbon-based world economy will begin and will seriously affect the type of society experienced by future generations (Dorian et al., 2006).