TVs, Printers, microwaves, chargers, DVD players, desktop computers and many other devices all drain energy when turned off or not in use. This drain is known as ‘vampire’ or ‘standby’ power and is responsible for a huge amount of energy loss each year. Since that energy is largely generated by burning fossil fuels, vampire power accelerates the rate of global warming as well as raising your electricity bill.
So how can you identify an energy vampire? Unfortunately it is not as simple as throwing holy water at your devices. There are, however, some good rules of thumb. Anything that can be turned on with a remote control is likely an energy vampire, since the sensor which picks up the signal must remain on 24/7. Another likely culprit is any device, like microwaves or radios, which constantly displays the time on a screen. There are, however, many other devices which consume power when not in use but show no external signs of doing so.
This issue negatively affects both the bank accounts of the average consumer and the global effort to combat climate change. Compared to dismantling the fossil fuel industry or convincing everyone to stop eating meat, this is a relatively easy fix. One way to slay vampire power is on the side of the consumer. If you buy a couple of extension cords with on/off switches, you can easily cut power to things like TVs and printers when they are not in use. Try keeping your remote control beside the extension cord so that you can flip the switch when you go to pick it up. There is, however, only so much we can do.
The more promising solution to vampire power is technical and is the responsibility of electronics manufacturers. For example, energy-saving devices can be built which automatically cut power when not in use for a certain amount of time. Another example would be phone or laptop chargers which cut the power when the device is fully charged or unplugged. It is estimated that changes to the power circuits of devices could reduce vampire power by as much as 90%, so manufacturers have the power to largely fix this issue all by themselves. One problem with this is that consumers are more likely to buy, for example, a TV which can be turned on remotely, so manufacturers have an incentive to keep producing goods which drain power when not in use.
Cutting vampire power would allow us to supply many more people with electricity without a corresponding increase in CO2 emissions. Improvements in efficiency such as this will be necessary to fight climate change, but must occur in tandem with a number of other tactics, including a conscious effort to reduce energy consumption across the board. It is the responsibility of manufacturers and consumers alike (but mainly manufacturers) to be careful about how much power is being used, and to identify and eliminate any power drain which is not absolutely necessary.
It has become common knowledge that humanity needs to change the sources of our energy at an unprecedented rate if we are to avoid the worst effects of climate change. Renewable energy systems are the most promising means available to reduce our impact on the earth without giving up the comforts of readily available electricity. However, an issue with some renewables like wind and solar is that the energy is only available sometimes. There is no solar power without sunlight and no wind power without wind. In this article I’ll be looking at a type of solar power plant which avoids this problem in a most ingenious way.
One way to solve the storage problem might be to connect all our renewable energy infrastructure to a massive international grid. What this would achieve is that excess solar power from a hot day in San Francisco could be used to power Beijing in the middle of the night, or excess wind power from blustery Ireland could be used to power gustless Brazil. This is a very good idea in theory but it has its drawbacks. Consider the sheer quantities of copper and rubber required to connect every solar and wind farm in the world to every home or business which requires their energy. And what about the time it would take for such an ambitious project to reach completion? Climate change is already here and will soon become entirely irreversible without swift and decisive action.
So how else can we store and distribute renewable energy? The answer seems very simple; build a battery. If you need solar power at night, why not store the electricity generated during the day rather than transporting it to the other side of the world? This, however, is far easier said than done. The current generation of lead-acid (car) and lithium-ion (phone) batteries are remarkable works of engineering. They are not, however, up to the task of storing the amount of energy we need them to store without seriously depleting natural resources like rare-earth metals. We are badly in need of a breakthrough. Lead-acid batteries have been working on the same basic principle since their invention by Gaston Plante in 1859 and are still one of the most widely used rechargeable batteries on the market. In this article, I’ll be looking at a new way of storing solar power that may revolutionise the energy grid of the future.
‘Concentrating solar power’ (CSP) plants have been providing more and more people with electricity ever since they were first built on an industrial scale back in the 1980s. The difference between these solar plants and standard photovoltaic (PV) plants is the way in which the electricity is generated. In PV panels, solar energy is converted directly into electricity. In CSP, the heat energy from the sun is used to make steam which spins a turbine and this is what generates the electricity. This is roughly the same process used to generate power from coal, oil, natural gas, nuclear fission, incineration, plasma gasification and thermal wave power so the proof of concept is definitely there. The major advantage of CSP over PV is storage. If your plant is generating electricity directly from the sun, you need somewhere to store the electricity when it is not needed; a battery. If you are generating electricity from heat, on the other hand, you can store the sun’s energy in something called a heat transfer fluid (HTF). This is any fluid, like mineral oil, which retains heat well over time.
The most basic and widely used form of CSP is known as a ‘parabolic trough power plant’ (PTPP). The first documented use of this technology was Auguste Mouchout’s ‘solar steam engine’ in 1866. In PTPPs, mirrors focus sunlight onto tubes which contain a HTF. The mirrors are curved like those you might see in a house of fun and are arranged in troughs with the tubes of HTF running down the centre. Picture a hot dog but with mirrors rather than bread and tubes rather than a highly questionable meat-like substance. The hot HTF is transported through the tubes to a series of heat exchangers where it evaporates water to spin a steam turbine. If electricity is not needed at that moment, the hot HTF can instead be transported to a storage chamber from which it can be removed when the need arises for electricity. Once the heat has been converted into electricity, the HTF returns to the troughs to begin the process again. 97% of the CSP plants currently producing energy are PTPPs.
Parabolic mirror with tubes of HTF
PTPPs, however, are not the only type of CSP available. Back in 2011, a company called Solar Reserve received a loan of $737 million for a project called ‘Crescent Dunes’; a massive solar plant in the Nevada desert which can provide electricity to 75,000 homes, night and day. Crescent Dunes is what is known as a ‘power tower’ CSP plant. Power towers operate on the same basic principle as PTPPs, but rather than each mirror focusing sunlight onto a different section of tubing, all the sunlight is concentrated on one central tower. Focusing all the sunlight on one place means that the plant operates at much higher temperatures, greatly increasing efficiency. This design also does not require expensive curved mirrors like PTPPs. The plant instead uses ‘heliostats’, flat mirrors which track the sun and change their position to maximise the amount of sunlight hitting the tower.
The real genius of the project is what is contained within the tower. Inside the tower is a mixture of potassium nitrate and sodium nitrate; also known as salt! More specifically, saltpeter. Sodium nitrate is currently used to preserve certain foods and is the reason bacon goes green if left uneaten for too long. In power towers, the salt is heated by the sunlight reflected off the mirrors until it is molten and packed to the brim with energy. The salt is cheap and extremely good at retaining heat, acting as a kind of thermal battery. This means that power towers can continue to provide energy long after the sun has stopped shining. What’s more, salt can be used at much higher temperatures than any of its competitors. One issue with using molten salt is that it can freeze in the pipes. For this reason, new types of solar salt are being developed which have much lower melting points.
One apparent issue with this design is the effect on birds. If you have thousands of mirrors concentrating the blazing sunlight of the desert into one spot, any bird that is unfortunate enough to fly through the firing line could be killed by direct heat. There have even been reports of birds bursting into flames mid-air then crashing down to earth like meteorites. We have decimated insect populations around the world, depriving many birds of their food source, and scientists estimate that between 100 million and 1 billion birds die each year by flying into buildings in the US alone. Given these facts, it could be argued that bird deaths are an unacceptable side-effect of power towers However, recent studies of bird deaths in a number of power towers have shown that initial estimates may have been wildly exaggerated.
Another consideration is that the negative effects suffered by birds if climate change goes unchecked greatly outweigh the effects they will suffer from concentrated solar, particularly given the recent assessments which show that the damage to bird populations from CSP is far less severe than was previously thought. There is certainly merit to this argument. We need to develop and roll out effective energy alternatives very soon or else birds, mammals, fish and insects alike will all suffer the worst effects of climate change.
It seems that CSP plants are getting better and better at mitigating the risk to bird populations. Each year the number of deaths goes down as adjustments are made to what is still a very new technology. It may seem cold and calculated to talk of flaming birds like mere teething pains, but we need to make these kinds of hard decisions if we are to ensure that we leave a habitable planet to future generations of people and birds alike.
In PTPPs, the sunlight is concentrated on a massive number of different points which are at ground level, meaning that the threat to birds is greatly reduced. However, there are a number of drawbacks. First and perhaps most important is that power towers are far more efficient at converting heat into electricity. This is partly due to the higher operating temperatures but is also affected by the surface area on which heat-loss can occur. If you concentrate all the sunlight onto one point, there is a much smaller area in which heat can radiate out into the atmosphere. Another major factor is how much of resources like oil, metal, water or salt are required for the process. In power towers, you only need enough HTF at any given moment to fill the relatively small space at the top of the tower. If you are constantly heating several kilometres of pipes, on the other hand, you will lose a lot more heat to radiation and use a lot more resources in the process.
Like many sustainable technologies, there are a number of advantages and disadvantages to CSP. When it comes to large-scale energy production, CSP seems to have PV beat, but If you are just looking to power your own house, PV rooftop solar panels are far easier to install and provide you with a personal energy supply. In the US, you can also make money from producing excess energy for the grid, with the UK set to follow suit in January of 2020 after much controversy and tomfoolery on the part of the government. Right now, good PV panels convert roughly 20% of sunlight into electricity but researchers think that number could theoretically be brought as high as 80% with a few breakthroughs. When it comes to deciding which type of CSP is best, I will leave that up to you.
Power towers are far more efficient and require far fewer resources to generate the same amount of energy. Despite initial exaggerations, however, power towers do pose a threat to birds, particularly if new plants keep being built. What’s more, they do not have a proven track record as long as their rival. What is certain is that if we do not transition to cleaner forms of energy ASAP, the consequences will be far more severe than most people think.
We will see an acceleration of biodiversity loss and an increase in the frequency and severity of natural disasters like hurricanes and floods. Large areas of land will become inarable, greatly reducing our food supply, and hundreds of millions of people will be exposed to extended periods of drought. Depending on which predictions are correct, the emissions reductions brought about by technologies like CSP could easily end up saving more lives than were lost to the holocaust. If that is not worth investing in, then I truly don’t know what is.
Even in this futuristic world of ours, all our electricity is generated by simply spinning a turbine. The fossil fuels which are bringing us ever closer to a complete climate catastrophe are not just used to power our cars, but also to create steam which generates the electricity needed for everything from phones to lightbulbs. This is exactly the same principle employed by nuclear power plants. In both cases, fuel is used to create heat, which is used to generate electricity. There are ways, however, to generate electricity which do not require heat at all. Some renewable technologies harness the vast mechanical power available from a planet that is in constant motion. Wave power generators (WPGs) are a possible energy source of the future, but how do they compare with their rivals?
It is worth quickly comparing ocean energy and wind energy since the two are similar in a number of ways. This is why underwater turbines closely resemble those of wind farms. A major difference between the two is the potential energy contained within. Water is nearly 800 times denser than air, meaning that the same volume, travelling at the same speed, contains much more power. What this means on the practical side is that much smaller devices can produce the same yield of energy.
A major difference between WPGs and tidal power is the source of energy. Tides result from the gravitational pull of the moon dragging water up and down our shores as it passes by above us. WPGs, alternatively, find their energy source in the sun. Solar radiation does not heat the earth evenly. The air in places which receive more heat rises upwards, allowing colder air to rush in to take its place. That rushing of air is what we call wind. Since wind is the driving force behind waves, any energy that we harvest from waves comes indirectly from the heat of the sun. It is for this reason that WPGs are considered a renewable technology.
Tidal power is perhaps the most reliable source of energy on earth. Twice a day like clockwork, unimaginably vast quantities of water rush in and out of our coasts. Globally, there is as much power available from tides alone as there would be from nearly 5 and a half billion coal-burning plants. One of the problems, however, is that only a very small fraction of this energy could actually be harvested. There are only 40 or so places in the world where the difference between low and high tide is great enough to produce a worthwhile amount of power. One way that the power of the tides can be harnessed in such places is by building tidal ‘barrages’. These consist of huge dams which trap water from the rising tide, then release it slowly when the tide is low. As the water passes through the dam back into the sea, it spins a series of turbines to generate electricity.
WPGs come in a variety of forms. One very cool design that was deployed in the ocean as far back as 2004 resembles a giant sea-snake. Each segment of the snake is attached to the next by hinge joints which are connected to hydraulic rams. As the sections of the snake move back and forth over the waves, the hydraulic rams drive a series of electrical generators.
Another simple yet ingenious way of harnessing the power of waves is by using a device known as an oscillating water column (OWC). These machines consist of a hollow cylinder containing a turbine which is attached to a buoy. As the waves pass by underneath, air is forced up through the cylinder, spinning a turbine. What makes these devices truly remarkable is the special kind of turbine contained within. The so-called ‘Well’s Turbine’ is shaped in such a way that it can generate electricity regardless of which way the air is flowing. This means that power can be harnessed when the device is rising to the crest of a wave and also when it is falling to a trough, doubling the overall efficiency.
The final method for generating electricity from the ocean is called ocean thermal energy conversion (OTEC). This is another way we can indirectly generate solar energy using the ocean as a middle man. The way OTEC works is that a liquid with a low boiling point (like ammonia) is evaporated by the warm surface water of the ocean and expands, spinning a turbine. The ammonia vapour is then condensed using cold seawater and returned to the evaporation chamber to start the process over again. The technology required for this method is simple and rapidly improving, meaning that OTEC is very much one to watch out for in the coming years.
So, which is better, WPGs or tidal barrages? WPGs hold greater promise in my view, largely because tidal barrages can be devastating to already strained marine ecosystems. Think about it; much of the ocean’s life is concentrated close to the shore. As the tide rises, both water and marine life can pass freely through the dam. Once that waterway is shut, however, the only way back to the sea is through a series of rotating blades. Many barrages are built on estuaries where rivers meet the sea. By preventing free movement through these estuaries, barrages can also seriously disrupt the spawning patterns of fish like salmon. WPGs, floating on the surface in open water, are much easier to build in a way that’s hospitable to marine life.
This is of vital importance; through plastic pollution, overfishing and ghost fishing, we have already utterly decimated almost all marine life. With plastic pollution and ocean acidification set to get much worse, we simply cannot afford to do any more harm to the beautiful animals that reside beneath the waves. If a plan is to be truly environmentally friendly, it must consider not only the CO2 it will emit, but also the effects it will have on our fellow animals. It is this major issue, coupled with the location problem mentioned earlier, which means that WPGs hold more promise than tidal barrages. In any case, it is clear that as both the financial and environmental costs of fossil fuels rise in the coming decades, blue power will assume an increasingly important position in the global energy industry.
Humans have an incredibly extensive waste problem. Right now, most of that waste is sent to landfills where it takes up space for thousands of years, leaching harmful chemicals and gases into the soil and atmosphere. Alternatively, we send our waste to incinerators which burn it for energy, but which release harmful greenhouse gases (GHGs) and toxic by-products in the process. A large proportion of our plastic waste ends up in the ocean, where it strangles and poisons fish, seabirds and marine mammals. What if I told you that there was a way to get rid of almost any type of waste in one machine, that the machine would release no harmful chemicals or GHGs, and that the process would produce useful by-products and excess energy that could be sold back to the grid? Such a machine exists right now; the plasma waste converter (PWC).
While incinerators are able to extract about 15% of the potential energy from rubbish, PWCs can extract an incredible 80% through a process called ‘gasification’. Plasma is ionised gas, meaning that it contains roughly equal numbers of positively charged ions and negatively charged electrons. It is often called the fourth state of matter since its characteristics are so different to those of liquids, solids and gases.
One way you can make plasma is by creating an arc of electricity between two rods, then passing a gas like argon through it. This set-up is known as a plasma torch and can heat gases to a higher temperature than the surface of the sun. Plasma torches were invented by NASA in the 60s to test how much heat the hulls of their spaceships could withstand. The crucial difference between using a plasma torch and using an incinerator is that in PWCs, combustion doesn’t take place. That means no smoke, no GHGs and no ash. The plasma breaks down the bonds between atoms, separating them into very simple forms. Despite the extremely high temperatures, it would be wrong to say that the waste is being ‘burned’; rather it is being decomposed at an accelerated rate.
One of the products of gasification is, you guessed it, gas. This energy-rich gas, known as syngas, is largely made up of hydrogen and carbon monoxide. Syngas mainly comes from the gasification of organic matter. As the gas expands, it spins a turbine, generating electricity. The high temperature of the gas can also be used to evaporate water, generating steam to turn another turbine. The syngas itself can then be burned for fuel or scrubbed with water and released safely. Remember, all of this energy production and revenue is coming from rubbish. We are talking about the plastics that are decimating marine life. Metals, fabrics, wood, even toxic or hazardous waste from industrial run-off or medical facilities. This is stuff that we desperately need to get rid of and by getting rid of it like this, we can also take some of the stress off an already strained energy production sector.
The solid by-product of gasification is called ‘slag’. Slag is produced mainly from inorganic materials like metals. It can be used in construction to bulk up concrete and tarmac, making it a very useful commodity. The molten slag also pools at the bottom of the chamber and helps to maintain the temperature, reducing the energy consumption of the PWC. The real magic happens when you pass compressed air through molten slag to create a material known as ‘rock wool’. Rock wool is currently made by drilling into rock, melting it down and spinning it in a centrifuge. Made in this way, rock wool is sold at one US dollar per pound. When it’s made of rubbish instead, it can be sold at just ten cent per pound.
Rock wool can be used in a number of ways. As an insulation material, it is twice as efficient as fibreglass and could significantly decrease heating and air conditioning bills, further reducing the carbon footprint of gasification. Surprisingly, you can also hydroponically grow plants from seed in rock wool. Perhaps its most amazing use is that it can clean up oil spills. Rock wool is lighter than water and extremely absorbent. This means that if you spread it out over the surface of an oil spill, it will float and absorb all the oil. The rock wool can then be collected with relative ease. Slag and rock wool are two more saleable products that can increase the economic viability of plasma waste conversion.
PWCs are currently being built all around the world. Some plants are already so efficient that they need to take rubbish out of landfills to use as feedstock. There is even a mobile plasma torch on the back of a truck in the US which can be jammed straight into landfills, which act as makeshift gasification chambers. The need to reduce GHG emissions and simultaneously fix our massive waste problem has generated huge interest in PWCs in recent years. Landfills have only one way to make money; they charge you a ‘tipping fee’ for getting rid of your waste. Since PWCs can generate revenue from both energy production and by-products, they can make their tipping fees much more competitive.
So why haven’t these things solved the problems of pollution and climate change already? The answer is largely that PWCs are still a relatively new technology. The cost of building and operating one is still much higher than that of some of its competitors including landfills and incinerators. There has not yet been standardisation of the design and thus the huge and complex machinery must be custom-built every time. The energy needed to power PWCs is also very high, especially compared to incineration, which requires only a match. It must be said, however, that although it takes a lot of energy to run a PWC, you will very quickly make all that energy back and more. PWCs are extremely efficient long-term; unfortunately, short-term profits dictate much of what happens in society.
One worry is that by making waste a profitable commodity, we encourage people and companies to keep polluting with impunity. The best way to solve pollution is not to pollute more and then clean it up better. It is to reduce the amount of pollution we are producing, whether that is by reducing our individual consumption, or by researching innovative ways to package our goods without making a mess. There is, on the other hand, already a lot of waste out there, languishing in landfills and contributing to the decimation of marine ecosystems. The best thing to do with all that waste is to get rid of it with the fewest possible emissions and the most possible benefits. PWCs may be just the technology for the job.
The price of fossil fuels is slowly being raised by various economic policies to reflect the cost to life on earth and we need to find as many alternative sources of energy as we can. With countless landfills already full and the world still producing around 2 billion tonnes of waste per year, rubbish will not be scarce for a very long time. This really is a win win win win win. One machine can get rid of harmful waste, cut GHG emissions, produce fuel, energy and construction materials and clean up oil spills all while making a profit. An investment in plasma waste converters is not only economically sound, it is also an investment in the future of our planet.
Small Change 