Today the world of energy has many of the features established in the 20th century:
– Energy consumption grows on average at 2% per year, most of it (80%) originates in fossil fuels
– Energy growth is driven by population growth and economic growth, now predominantly in developing countries
and high levels of consumption in the developed countries
– 3 billion people don’t have access to basic energy services and have to cook with solid fuels

However, the present path of uninterrupted reliance on fossil fuels poses four challenges to sustainability:
– Soaring greenhouse gas emissions
– Decreasing energy security
– Air pollution at the local and regional levels with resulting health problems
– Lack of universal access to energy services

Most reviews of the energy system needed for the 21st century start with “business as usual” futures and then analyze the effectiveness of specific corrections of course. For many the preferred options are technological fixes such as such as carbon capture and storage (CCS), nuclear energy and even geo-engineering schemes. However, to achieve sustainable development all the needed attributes of energy services, that is availability, affordability, access, security, health, climate and environmental protection, must be met concurrently.

– Stabilizing global climate change to 2°C above pre-industrial levels to be achieved in the 21st century
– Enhanced energy security by diversification and resilience of energy supply (particularly the dependence on imported oil),
– Eliminating household and ambient air pollution, andEssential technology-related requirements for radical energy transformation:
• significantly larger investment in energy efficiency improvements especially end-use across all sectors, with a focus on new investments as well as major retrofits;
• rapid escalation of investments in renewable energies: hydropower, wind, solar energy, modern bioenergy, and
geothermal, as well as the smart grids that enable more effective utilization of renewable energies;
• reaching universal access to modern forms of energy and cleaner cooking through micro-financing and subsidies;
• use of fossil fuels and bioenergy at the same facilities for the efficient co-production of multiple energy carriers and
chemicals with full-scale deployment of carbon capture and storage; and
• on one extreme nuclear energy could make a significant contribution to global electricity generation, but on the
other extreme, it could be phased out.

The world is undergoing severe and rapid change involving significant challenges. Although this situation poses a threat, it also offers a unique opportunity – a window of time in which to create a new, more sustainable,
more equitable world, provided that the challenges can be
addressed promptly and adequately. Energy is a pivotal area for actions to help address the challenges.
The interrelated world brought about by growth and globalization has increased the linkages among the major challenges of the 21st century.
We do not have the luxury of being able to rank them in order of priority.
As they are closely linked and interdependent, the task of addressing them simultaneously is imperative.