See It’s all about energy for a pretty decent, concise summary of alternatives:
The global energy scene is currently dominated by two overriding concerns that strongly affect decisions on energy development priorities: security of supply and climate change.
Worldwide, renewable energy is still dominated by the ”old” renewables: hydropower and traditional biomass. They supply respectively six and nine percent of global primary energy demand.
Only about two percent of the world’s primary energy is currently provided by ”new” renewable sources such as wind, photovoltaics (solar cells) and mini- and micro-hydro.
If greenhouse gas emissions are to be reduced substantially, renewable energy technologies arguably have to obtain a greater share of the global energy supply. But even if renewables get a larger market share, this only takes care of the climate problem. To become commonplace, they also need to satisfy the demand for security of supply.
”One of the main challenges is that all of the sophisticated sustainable energy technologies – be it wind, solar, wave or something else – produce energy when it suits them. But Mrs. Jensen does her laundry when it suits her,” says Hans Larsen, Head of Division at Risø National Laboratory for Sustainable Energy, Denmark, and a review editor of the IPCC Fourth Assessment Report.
The problem is storing the energy for later use and also transporting it over greater distances with a minimum of loss.
”If someone were to come up with a major storage breakthrough, the world’s entire need for energy could be covered by renewable energy,” says Hans Larsen.
In addition to storing and transporting energy, two other factors are a key to optimizing energy use and obtaining a higher degree of sustainability: intelligence and energy systems.
”The intelligent energy system is an area you don’t think so much about, but where there is a whole lot to be gained. It is key to making all current and future energy technologies meet and work together,” says Hans Larsen.
Below are listed 12 energy technologies. The overview shows the current technological status and growth of each technology, as well as the major challenges and barriers for further exploitation. The current and projected global market shares are noted, and so are the possible adverse effects of the technology. The overview is based on Risø Energy Report 7 – Future low carbon energy systems.
The technologies covered in the list following the above quote is:
- Wind
- Solar cells
- Solar thermal
- Biomass-based fuels for transport
- Biomass – combustion, gasification and pyrolysis
- Fossil fuels – combustion and gasification
- Nuclear energy
- Fusion energy
- Geothermal energy
- Hydro, ocean, wave and tidal
- Fuel cells
- Hydrogen
I could quibble with a few details, but overall it looks like a solid treatment.
