Video courtesy of TechnologicVehicles
The automobile industry is currently lauding the progress made with hybrid and plug-in electric engines, identifying them as the future of mass transport. These cars produce less carbon and other harmful gases than traditional petrol-powered vehicles, and reduce dependence on oil and the price fluctuations that come with the highly politicised natural resource.
All this back-slapping, however, overlooks one key fact: while the car itself may be green, in most countries electrical energy is not actually green at all.
Credit: Toyota Motor Europe
It would be wrong to blame the car companies in this respect; after all, it's not their fault that so many countries are still working on green energy policies.
But the fact remains that electric cars are not all that green, if powering them puts further strain on countries that are heavily reliant on fossil fuels and already struggling to meet their energy needs. Electric cars are the greenest method of transport in Iceland, where all domestic energy needs are met by a combination of hydroelectric and geothermal power production. In Australia, 11% of energy production comes from renewable sources and 74% is created by burning coal. How much extra coal would be burned as
a result of converting the population to electric motoring is something that is difficult to measure.
As it's clear among the scientific community that electric vehicles don't present an immediate solution to the problem, the type of fuels that we use in our cars remains an interesting area for research. Finding a way to reduce the car's carbon footprint separately from national energy policy could be the true future of greener motoring.
Video courtesy of Ohio State University Extension
We can produce biofuels efficient enough to power cars from a surprising number of plant crops, breaking down the sugars within them to produce an ethanol fuel. Unfortunately, it's a little more complicated than just growing enough fuel to power our cars.
While scientists experiment with all kinds of crops for biofuel production, from corn, sugar cane and miscanthus to soyabeans, palm oil and switchgrass, there is yet to be established one which fits the bill as the ideal biofuel crop, and for a variety of reasons.
Ethanol doesn't offer the same energy delivery as petroleum to start off with, and different plant products provide different strengths of ethanol fuel. Some of the better plant products in terms of ethanol production have their own problems: take palm oil, for example, a very versatile oil grown in tropical regions.
To meet rising demand for this substance, deforestation has been occurring on a massive scale, harming wildlife, displacing communities and contributing to climate change.
Then there's the food issue. Typically, the parts of plants that we eat contain more of the necessary sugars needed for ethanol production - it's why we eat those bits. But when parts of the world are going hungry is it sustainable - or even ethically correct - to be burning food for fuel? And even with non-food plant crops, should this fertile land not reserved to grow food in developing countries?
So while biofuels have been around for some time, the future of fuel is still uncertain. But that doesn't mean there aren't areas of promise...
Could the answer to our fuel needs be sitting in our kitchen bins? According to a report produced by the International Council on Clean Transportation, the Institute of European Environmental Policy and a host of private companies, repurposing the everyday waste we produce and turning it into biofuel could contribute a significant amount to our transport fuel needs in the next 15 years.
Wasted: Europe's Untapped Resource suggests that if all the wastes and residues that are sustainably available in the European Union were converted only to biofuels, this could supply 16 per cent of road transport fuel across the EU by 2030. It had been thought that the amount of waste available to be used in this manner was insufficient to make a significant contribution to fuel requirements, but the report disputes this. From an environmental perspective, the potential is very promising. Carbon emission savings from using waste-sourced biofuels are estimated to be between 65 and 80 per cent by the report - an important consideration with any 'new' fuel, since the European Commission expects the transport sector to be the EU's biggest source of carbon emissions by 2030.
Defining 'waste' is not straightforward, as since the beginning of time we have looked to find ways to make use of the things that other people don't need.
We've got rather good at it, too. With waste paper, food and plant material being used in a variety of industries, diverting this to biofuel production could have a detrimental impact. However, with municipal solid waste (MSW), the rubbish collected from our homes and dumped in landfill sites, there is a rich source of untapped energy. According to the Wasted report, converting MSW into ethanol fuel could result in a 296% per cent saving of greenhouse gas emissions, and sustainable availability of MSW for biofuel conversion is around 44 million tonnes per year across Europe. An industry processing sustainable waste material for use in biofuels could also create 300,000 jobs in Europe - many of which would be in rural areas.
The technology to convert waste into biofuel is already in place - all that is really needed is for governments to back it as part of their environmental policies. The snag, as with most green policies, is whether they are willing to make immediate investment for a gain that will only be seen in the long term.
Algae gets a fairly bad rap, since most people only really come across it when it's spoiling the look of a garden pond or clogging up a river, but we would be nowhere without it. Science cannot seem to decide exactly how much of the Earth's oxygen is produced by marine algae, but a relatively conservative estimate puts it in the region of 70%.
Algae photosynthesises as carbon dioxide bubbles through nutrient-rich water, and it produces a significant amount of oil as it grows - oil which can be used for biofuel.
It's difficult to even compare the biofuel potential of algae to agricultural biofuels such as rapeseed. With agricultural crops, you can harvest once or twice a year, depending on the crop and the climate. Algae can double its mass in a single day. What's more, its oil production is far superior to that of agricultural crops, including palms and soybeans. If you were to harvest an acre of algae, you would have 15 times more oil than you would with an acre of crops.
So just how useful is algae oil?
On a molecular level, it's actually very similar to the crude oil from which we derive petroleum. It's the small organisms such as algae, heated over millions of years below the surface of the Earth, that create the reservoirs of crude oil that we covet so much. Luckily, we don't need millions of years to convert algae oil into a refinable form of crude; modern science has advanced this heating process, and in December, scientists at the US Department of Energy's Pacific Northwest National Laboratory announced they had managed to take a small mixture of algae and water and turn it into a form of crude oil in just one hour.
Credit: IGV Biotech
While the idea of creating more crude oil may not seem like the future of fuel from an environmental point of view - we are after all still burning oil - the entire process is much closer to being carbon neutral than using petroleum, as the algae processes carbon dioxide and produces oxygen as it grows.
Not only that, the by-products of extracting oil from algae also have many energy-related and agricultural uses, and turning this into an industry would not be massively problematic algae can grow pretty much anywhere there is spare water, and the processing can be done with existing refineries' infrastructure.
There is also a need to be a little pragmatic: certain types of vehicles - jets and tanks, for example - simply can't run on ethanol-style fuels. Petrol and diesel will still be used until someone invents a fuel that produces enough power to works with all our existing vehicle technology; algae could fit the bill for a greener future.
What if we didn't have to drill our fuel out of the ground or even grow it, and instead we just pulled it out of the air? Hydrogen is seen by many as the ultimate green fuel, since it's found in water, and if you extract it you're left with oxygen molecules. If only getting it from the lab to the tank of your family saloon wasn't so difficult.
To extract hydrogen from water requires a lot of energy; you have to run electricity through it to separate the atoms, so again we come back to the sustainability and environmental impact of how this initial power is generated.
Another way to produce hydrogen in large quantities is to extract it from methane. Methane is a greenhouse gas, so that's a plus point, but the process produces two other greenhouse gases: carbon dioxide and carbon monoxide. Hydrogen also isn't actually an energy source, it's an energy carrier. Using it as a fuel means combining it with oxygen, and the energy that powers an engine comes from the radiant heat produced by the newly-formed water molecules. For hydrogen fuel to be viable on a large scale, this process needs to be able to work forwards and backwards with a sustainable source of energy.
A recent discovery by scientists from Stanford University in the US may offer some promise, combining the hydrogen process with solar power to create a cheaper way to separate hydrogen and oxygen. The key is in the water splitter device, which is traditionally where the process becomes 'expensive'. Precious metals such as iridium have been used before, as have cheaper materials such as silicon, but the former is not sustainable and the latter corrodes in water. The Stanford model gets around this by coating the silicon splitter in cheap corrosion-resistant nickel.
The device works by absorbing light through solar cells and diverting that energy into water via electrodes. This splits the water into oxygen, which is released into the atmosphere, and hydrogen, which is stored. When the solar cells are not sufficient to power the vehicle (which is often - the main reason why solar on its own is not a viable fuel source) the process is reversed, with oxygen being drawn from the atmosphere and combined with hydrogen, creating water and that all-important energy.
At the moment, this process is still very much in the experimental phase, and is a long way off being something which could be mass produced to power engines. Solar panels too would have to make significant improvements in the energy-harnessing ability. However, the technology indicates that the ultimate sustainable green fuel - cars running on sunlight and thin air - may be the true fuel of the future.