FUTURE ENERGY RESOURCES

• Hydrogen energy • Fusion energy

Data collection and presentation by Carl Denef, Januari 2014

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Hydrogen energy• Hydrogen gas can be used to generate heat by combustion and to power

transportation vehicles in combustion motors and in electrochemical fuel cells (read more) to power electric cars and buses.

• In all applications the end product is water. Hydrogen is therefore a clean and, if prepared from water, a renewable energy source that could become of great importance in mitigating the deleterious effects of greenhouse gases emitted by fossil energy devices.

• Currently, global hydrogen production is 48% from natural gas, 30% from oil, and 18% from coal; water electrolysis accounts for only 4%.

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Hydrogen is not available in nature and must be prepared by one of following methods:

• Generation from methane by steam methane reforming. This is most frequently used today, but production emits greenhouse gasses (CH4 + H2O → CO + 3 H2 at 1700 °C and CO + H2O → CO2 + H2 at 170 °C). The problem is the additional cost to get rid of the CO2.

• Electrolysis of water. Does not produce greenhouse gasses, except for small amount of NOx

• Photocatalytic water splitting by solar light in the presence of TiO2 as catalyst with a co-catalyst such as Pt. Does not produce greenhouse gasses

• Biomass gasification • Coal gasification This proces generates a mixture of CO2, CO, H2O and H2. The problem is the additional cost to get rid of the CO2 and CO. Europe, Japan, USA and New Zealand have active programs. A problem is that coal gasification has been shown to generate by-products that contaminate the soil and groundwater in and around the manufacturing plant

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Hydrogen storage

• Hydrogen can be stored as a compressed gas, as liquified gas or as a solid material in magnesium hydride or magnesium-nickel hydride. Storing hydrogen on-board is a challenge as illustrated in the figure below, where the volume and weight of storing of 4 kg of hydrogen is shown for different storage methods. 4 kg of hydrogen is enough to drive a fuel cell car for 500  km. Source

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Prospects of hydrogen energy

Hydrogen energy is a potential novel energy type for the future as it does not emit greenhouse gas during energy use, it is sustainable and can be produced locally. Read more.

Hydrogen is at present very energy demanding to prepare. When prepared by electrolysis of water, its EROEI (energy returned on energy invested ratio) is <1. To produce 1 kg of hydrogen (specific energy = 143 MJ/kg or ~40 kWh/kg) , 50 - 79 kWh of electricity is required. However, hydrogen can gain interest as an energy carrier and become a sustainable zero-emission energy source if electrolysis is driven by electricity from wind, solar or geothermal sources. Currently various other methods to prepare hydrogen from water are being tested. Read more

It may take several decades before widespread commercial use is possible. Nevertheless, there are over 100 fuel cell buses deployed around the world today. Hydrogen combustion cars have been produced by BMW, Mazda, Ford and Toyota. At present, hydrogen cars can make 400 km between refueling and are very expensive.

Whereas conventional combustion-driven vehicles can easily be converted to hydrogen combustion vehicles, fuel cell-driven vehicle designs are not as yet robust enough to survive in below-freezing environments.

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Other drawbacks • High tankage weights, very high storage vessel pressures and large investment in

infrastructure required to fuel vehicles • • Although hydrogen has a larger specific energy content per unit weight than other

fuels, it has a 10 x lower energy content per unit volume (compressed at 300 bar)

• Hydrogen poses no more safety risks than petrol or natural gas when used with appropriate precaution. There are safety concerns associated with very high pressures and low temperatures necessary for hydrogen storage methods. Storage as metal hydrides is safer.

• Hydrogen leaks may interact with chemical cycles of H2O and various greenhouse gases in the stratosphere and with microbes in the soil. Read more

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Fusion energyFusion power is based on the fusion of hydrogen

to helium which releases 10 times more heat energy than fission of uranium isotopes. Proposed fuels are the hydrogen isotopes deuterium and tritium, and in many current designs also lithium and boron.

Experts believe fusion to be a promising future energy source due to its prospective power output, the short lived radioactivity of the produced waste, its low carbon emissions and its safety. With a fusion energy output equal to the current global primary energy consumption, the known current lithium reserves on land would last 3000 years, lithium from sea water would last 60 million

years, and a more complicated fusion process, using only deuterium from sea water, would have fuel for 150 billion years[97] , which is far beyond the life span of the sun.

There is no technical potential yet for economical fusion energy generation, as there is still more energy required to generate the heat necessary for starting the fusion reaction than there is energy obtained from the fusion process. Most optimistic prospects do not expect technical realization before 2050 and, even then, it would take a long time to generalize the technology over the world. Hope giving is that recently a start was made with the building of the first experimental fusion reactor ITER near the French village Cadarache.

View other slide shows on hydrogen and fusion energy