Difference between revisions of "Energy"
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However, things are getting even better: solar technology is becoming cheaper, more efficient and more accessible. Solar technologies can be divided into first, second and third generation. First generation solar cells use silicon wafers to convert about 15% or 20% of the light to electricity and work only in direct sunlight. Most modern off-the-shelf solar panels are mostly first generation. Second generation solar cells are similar, but the silicon wafers are much thinner, on the nanometer scale, which reduces material used, allowing lower production costs and higher manufacturing capacity. {{wp|Thid_generation_photovoltaic_cell|The third generation of solar cells}} encompasses a range of technologies at various stages of development, including {{em}} | However, things are getting even better: solar technology is becoming cheaper, more efficient and more accessible. Solar technologies can be divided into first, second and third generation. First generation solar cells use silicon wafers to convert about 15% or 20% of the light to electricity and work only in direct sunlight. Most modern off-the-shelf solar panels are mostly first generation. Second generation solar cells are similar, but the silicon wafers are much thinner, on the nanometer scale, which reduces material used, allowing lower production costs and higher manufacturing capacity. {{wp|Thid_generation_photovoltaic_cell|The third generation of solar cells}} encompasses a range of technologies at various stages of development, including {{em}} | ||
| − | * Flexible {{wp|Polymer_solar_cell|polymer solar cells}} that can be integrated into paint, windows etc. for [[Ubiquitous | + | * Flexible {{wp|Polymer_solar_cell|polymer solar cells}} that can be integrated into paint, windows etc. for [[#Ubiquitous photovoltaics|ubiquitous PV]]. The conversion efficiency is currently low, around 3-5%, but this is improving. |
* {{wp|Dye-sensitized_solar_cells|Dye-sensitized cells}}. These have high conversion efficiencies | * {{wp|Dye-sensitized_solar_cells|Dye-sensitized cells}}. These have high conversion efficiencies | ||
* Multi-junction solar cells, which have extremely high conversion efficiency. There are prototypes that convert as much as 43%<sup>[http://www.inhabitat.com/2009/08/25/australian-scientists-develop-worlds-most-efficient-solar-cell/]</sup>. | * Multi-junction solar cells, which have extremely high conversion efficiency. There are prototypes that convert as much as 43%<sup>[http://www.inhabitat.com/2009/08/25/australian-scientists-develop-worlds-most-efficient-solar-cell/]</sup>. | ||
Revision as of 17:43, 4 July 2010
The human race currently requires 15 terawatts of energy[1]. This is a laughably tiny amount of energy compared to what is available around us: 72 terawatts of available wind energy at ground level[2], 150 terawatts in the jet streams[3], 44.2 terawatts of geothermal energy [4], 2 terawatts of easily-exploitable wave power[5] and 174,000 terawatts of solar energy[6]. We clearly have tens of thousands of times the energy we need, the key is our ability to harness this energy. This article explores existing and emerging technologies for doing this.
Steadily increasing energy efficiency 
due to improved system design and increasing cultural awareness should become a significant factor in our energy usage.
The issue currently is commercial economics. The bottom line is that with the current economic framework it is still 'cheaper' to pump oil out of the ground and burn it to produce power than use other more plentiful, renewable and environmentally benign sources. These alternative energy sources are sitting right in front of us waiting to be harnessed. It may be that open-source methods can bypass the incumbent economic system to enable plentiful, environmentally-friendly power.
A word on decentralization: some scenarios imagine our renewable electricity in the future coming from giant solar farms, wind farms and other renewable sources. However, for such farms to meet our needs, they have to cover an area the size of the USA ref. This is simply not feasible and would require bulldozing large areas of wilderness. However, solar, wind and geothermal energy can be very effective at a small scale. Each building, or group of buildings, can generate its own electricity on-site by putting solar panels on the roof, third-generation photovoltaics embedded in windows [7], a wind turbine or small geothermal generators. Even without technological evolution, we could meet all our energy needs today by fitting most buildings with small-scale renewable generators. It is likely that our electricity in the future will mostly come from such decentralized sources, supplemented by the occasional larger energy-farm, such as a wave power generator next to a coastal city.
We have these major sources of energy available to us, in no particular order and not including fossil fuels that we currently rely on for the majority of our energy today:
Contents
Generating energy
Solar
Because the amount of energy falling on the Earth from the Sun is ridiculously abundant, it is likely that solar power will form the bulk of our energy in a post-scarcity society, and the other sources mentioned here will supplement it, and be used in places with little sunshine. We are expected to need 30 terawatts of power by 2030 — about 0.02% of the 174,000 terawatts of solar energy that fall on Earth. 
However, things are getting even better: solar technology is becoming cheaper, more efficient and more accessible. Solar technologies can be divided into first, second and third generation. First generation solar cells use silicon wafers to convert about 15% or 20% of the light to electricity and work only in direct sunlight. Most modern off-the-shelf solar panels are mostly first generation. Second generation solar cells are similar, but the silicon wafers are much thinner, on the nanometer scale, which reduces material used, allowing lower production costs and higher manufacturing capacity. The third generation of solar cells encompasses a range of technologies at various stages of development, including —
- Flexible polymer solar cells that can be integrated into paint, windows etc. for ubiquitous PV. The conversion efficiency is currently low, around 3-5%, but this is improving.
- Dye-sensitized cells . These have high conversion efficiencies
- Multi-junction solar cells, which have extremely high conversion efficiency. There are prototypes that convert as much as 43%[8].
- Nanocrystals. Using nanoengineered crystals, it is theoretically possible to create solar panels with an efficiency of 60.3%[9]
- Microcontinuum are working on a nanoengineered solar cell that could convert infrared light with up to 80% efficiency. Half the energy that reaches us from the sun is in the invisible infrared range of spectrum, so finding a way to convert infrared to electricity opens up staggering amounts of energy. Infrared light is emitted by the ground at night, having been absorbed from sunlight during the day. If and when this technology comes to fruition, we could see thin, flexible coatings of solar cells that generate solar power even at night. This would enable constant solar power generation despite intermittent sunlight.
- Spray-on quantum dots. These could operate at efficiencies of 30%. Also work with infrared.
- Only a fraction of the solar energy that falls on a solar cell can be converted to electricity. Much of the rest turns into heat. However, this heat can also be used to generate electricity, as an alternative to, or in conjunction with, photovoltaics. Solar thermal (such as power tower & [10]. SHPEGS is an open-source design for a solar thermal generator. solar updraft tower )
Even if these technologies do not all ultimately pan out, one thing is certain: solar power is an evolving technology, with many promising avenues of research. As the technology improves, solar power becomes cheaper and more efficient. By contrast, oil and fossil fuels are stuck with a fixed efficiency, and becomes more expensive as accessible reserves are depleted.
When these technologies become mainstream, solar power will be a very attractive option. The ultimate evolution of this trend will be ubiquitous photovoltaics.
ocean thermal energy conversion
Prospective: Space solar power including solar power satellite , and stratospheric solar array
Ubiquitous photovoltaics
Ubiquitous PV will be the ultimate in post-scarcity energy. This refers to easily-applied, durable and very cheap photovoltaic surface coatings, using inexpensive raw materials and manufacture processes, that could cover the majority of roofs, pavements, roads and other surfaces. This vast distributed energy gathering area has the possibility of providing all of the energy requirements of modern society. Solar cells could even be woven into clothing, allowing mobile power for phones, personal computers etc. The range of electric vehicles could be greatly improved by integrating photovoltaics into the paint and windows. Photovoltaic cells have already been integrated with glass windows, such as SunTech's PhotoVol Glass system.
Conveniently, ubiquitous photovoltaics would mean that the greater the population concentration in an area, the greater the energy-generating surface would be.
Polymer solar cells , quantum dot solar cells, nanocrystals, or nanoantennae are potential enabling technologies.
Wind
Wind power lends itself easily to decentralization: turbines can be put on top of any building, taking up zero extra space. By putting the turbines on a tall pole, they reach the faster winds available higher up. Large-scale wind farms also take up very little space, as the diameter of the pole is the only bit that takes up land; the business-end of the machinery is up out of the way and the land in between wind turbines can be used for agriculture or any other purpose.
One technology we may see in the near-future is flying wind turbines that exploit the reliable, high-speed winds of the stratospheric jet-streams.
Ocean
wave, tidal, ocean currents
The waves bobbing up and down endlessly are a source of practically infinite energy. While engineers have looked for a way to harness this energy to make electricity for decades, the first commercially viable wave farm was opened in 2008[11].
Hydro-electric
Nuclear power
Nuclear fission (currently employed). Nuclear reprocessing by the Fast breeder reactor reduces the amount of waste, increases efficiency.
Prospective: nuclear fusion , accelerator-driven thorium-fuelled energy amplifier , and Travelling wave reactor . 3rd and 4th generation nuclear reactors are very safe.
Question of waste disposal. 1GW of nuclear generates only a modest 20 tons of waste. So if all our energy came from nuclear fission, we'd have 300,000 tons of waste (very dense, occupying a relatively small volume). However, this waste is dangerous.
Decommissioned warheads can be used as fuel.
Geothermal
shallow geothermal heat pumps , volcanic related geothermal and deep geothermal - Enhanced geothermal systems (EGS). See also Future of Geothermal Power (in the US) published by MIT and Google's funding of enhanced geothermal [12]. Small-scale thermal (not electric) geothermal heat pumps are a great way to heat houses year-round in cold places.
Biomass (carbon-neutral)
biofuel (algae), compost methane, fermented crop waste, algae, sustainable wood, and clean burning of: organic waste, animal dung and rubbish
Could be integrated with carbon capturing technologies to become better than carbon-neutral
Bacteria
Certain species of bacteria (such as geobacter) deposit electrons onto electrodes placed in their environment. Much work is still being done on optimizing the systems, but microbial fuel cells already provide a cheap and very resilient form of energy. A $40 system developed by Dr. Peter Girguis and Dr. Helen White has shown itself capable of producing 96W of power[13]. This system used inexpensive charcoal electrodes and can run for years and years without maintenance. Since then, a new strain of geobacter bacteria has been developed that has a power output eight times greater than previously known strains[14].
Microbial fuel cells can be synergized with composting toilets to create a system that disposes of human waste, fertilizes plants for food and also generates electricity.
- Bruce Logan research on Microbial fuel cells including advocacy on installing microbial fuel cells at wastewater treatment plants and a page on how to make your own
- microbialfuelcell.org
Recapturing waste energy
Just like there are untapped reserves of money in the back of your couch, there are untapped reserves of energy in the ambient surroundings. Though not normally discussed by renewable energy afficionados, the random wasted energy that is floating around us as motion and heat can be considered a form of clean, renewable energy. Devices to capture this energy can be fitted to anything from a car to a computer. Some examples —
- Trochoidal gear engine technology can be attached to machines such as factory robots to recapture the heat they generate and turn it back into useful energy [15].
- Piezoelectric crystals are crystals that generate electricity when shaken or squeezed. They have been used to recapture kinetic energy from the air flowing around a car [16] and in the suspension systems of cars.
- Kinetic generators such as the nPower PEG generate electricity whenever they are moved. Even just keeping one in your pocket while walking provides clean energy. What if devices like this were routinely fitted to our vehicles?
Regenerative braking is now a standard feature in electric cars. Whenever you use the brakes of your car, you are taking away its kinetic energy. This is normally wasted, but with regenerative braking, is recaptured and used later. This can provide 10% of the car's energy needs.
Storing energy
Batteries
Capacitors
Nanoengineering is enabling more and more efficient capacitors
Fuel cells
Hydrogen economy
Using energy
, "up to 75% of the electricity used in the U.S. today could be saved with efficiency measures that cost less than the electricity itself". When considering the energy needs of a post-scarcity world, it is important to recognize that most of the things people want to do - heat a building, wash clothes, light their homes - can be achieved with a fraction of the energy we currently use: LEDs are rapidly replacing fluorescent and incandescent bulbs as a light-source and can provide the same illumination with a quarter the energy, better-designed cars with lighter materials can greatly reduce energy consumption for transport, and for every appliance from refrigerators to dishwashers to ovens, there are design tricks that can produce the same functionality while greatly reducing energy consumption.
In many environments, the need for using energy to heat or cool buildings can be reduced to zero by use of proper insulation and architectural design.
Post-scarcity of energy will arise when we have both halves of the equation: abundant production of energy, and non-wasteful use of it.
