by Jeff Hardy
The aviation industry has been under environmental spotlight for quite some time now. It’s a rapidly growing industry and as it expands so does its carbon dioxide footprint. Two tools can be brought to bear on aviation to reduce its footprint, behavioural change and technological innovation. Since I don’t want to turn this blog into a rant about travel choices I think my best bet is to stick to technology.
Very crudely speaking, the way I see it is that there are three technological options for reducing the carbon emissions for aeroplanes, weight, design and fuels. Here I’m going to concentrate mainly on fuels but it is worth briefly discussing the other two as they are equally important.
I’m going to pick on the Boeing 787 to demonstrate how advances in lightweight materials and engine design can lead to lower carbon emissions. The 787 is constructed 50% from composite materials (carbon fibre reinforced plastics) leading to significant weight reductions. Some versions of the 787 will be powered by advanced Rolls Royce Trent 1000 engines which are very efficient and quiet engines. Combined these measures mean that some versions of the 787 will burn almost 30 per cent less fuel than previous generation airliners.
Whilst there plenty of room for further advances in reducing weight and innovative design, the inescapable fact is planes are currently fuelled by fossil fuel derived kerosene. So what are the options here? Well, if you believe a group of gifted and talented youngsters I taught when at the University of York green chemistry group then the answer is as follows. Take a standard passenger plane. Fill the back half with cows. Feed the cows a diet guaranteed to produce copious methane. Use the methane to power the plane. Provide passengers with gas masks and free milk. Inspired thinking, but perhaps not so practical.
More realistically there appear to be two options for fuels – biofuels and hydrogen. Both off these have been recently trialled with some early success.
In the case of biofuels, Virgin flew a jumbo jet between London's Heathrow and Amsterdam with one engine being fed enough biofuel to provide about 20% of its power. The biofuel was derived from Brazilian babassu nuts and coconuts. The key problem with using fuels derived from natural oils, according to Virgin, is that there exists the possibility that they could freeze at the low temperature at high altitude (for reference note how olive oil goes cloudy and viscous in cold weather). Not an insignificant problem it would appear.
A potential way around this is to make the biofuel in a different way. Biomass derived kerosene can made by converting biomass to synthesis gas (a mixture of carbon monoxide and hydrogen) by a process called gasification and converting the synthesis gas to kerosene through the Fischer-Tropsch process. I’d be happy to go into the chemistry of this if anyone is interested. The advantage of this route is that the kerosene produced is quite similar to that already used and thus should be compatible. In fact Airbus has successfully tested a fuel based on the similar gas to liquid technology, where natural gas is used instead of biomass as feedstock.
It is important that biofuels are derived from sustainable sources and that they have minimal carbon emissions across their whole life cycle. If the biofuel falls down on either of these criteria then it is difficult to see the advantage in its application. This has made the headlines recently in relation to the Renewable Transport Fuels Obligation.
Looking more to the future, you may have seen that Boeing have successfully tested the first manned, hydrogen-powered plane in Spain. The plane, powered by a hybrid battery and fuel cell system developed by UK firm Intelligent Energy, flew for around 20 minutes and landed safely. It’s unlikely that this technology will be suitable for powering commercial passenger aircraft, but it may be capable of providing a secondary source of energy.
This doesn’t rule out hydrogen as a potential aviation fuel in the future, far from it if you believe the claims of the European Space Agency. They are proposing a hydrogen fuelled supersonic passenger jet plane potentially capable of up to Mach 8 – blimey! Concorde on a good day managed a sluggish Mach 2. The plane could be capable of flying from Brussels to Sydney in 4.6 hours – that’s barely time to get comfy. The so called A2 is based on a special engine technology named Scimitar which seems to be described as a rocket engine with a turbo booster! It’s all rather exciting, but I think someway off so I should probably calm down a little.
For now it appears that the introduction of the A380 and the 787 may achieve some savings in carbon dioxide emissions per passenger (assuming they have a full quotient of passengers). However, it appears that in the short term, the only mechanism to reduce the environmental impact of flying is for people to fly less…
Friday, 11 April 2008
Friday, 4 April 2008
Water, water everywhere…
By Jeff Hardy
This week I have been inspired by water and energy, in fact specifically by a paper by French scientists [1] on harvesting energy from raindrops. In the authors own words “Our system recovers the vibration energy from a piezoelectric flexible structure impacted by a water drop”. What?!? Put more simply, some materials (in this case polyvinylidene fluoride) can convert mechanical energy into electrical energy. This is called the piezoelectric effect, and is similar to that which I described previously in power dressing. So as rain drops hit the material it generates an electrical current (naturally it’s a bit more complicated than this).
So how much power can you generate? The authors estimate that the available rain power in French regions with a continental climate to be almost 1 Wh per square metre per year. For comparison, in Scotland a south-facing roof receives between 700 - 1100 kWh/m2 of solar radiation during a year – oh dear. It’s probably a bit unfair to make this comparison now since this is very early in the development path of this technology. I also like this idea since I’m from the North West of England where it is very wet indeed.
This idea got me wondering about other novel ways in which water could be used to generate electricity. I thought it best to steer away from the classics such as watermills, hydroelectricity, wave and tidal power and generation of hydrogen through electrolysis or thermochemical methods. Instead I have dug out a couple of examples from the literature which interested me.
It appears that engineers at the University of Alberta in Canada have found that pumping water through microchannels in a glass disk can generate an electrical current [2]. In fact they claim “[that it is] the first new way to produce sustainable electricity in 160 years”.
How does it work? Forcing water through tiny glass channels is known to be tough because the channel walls become charged which creates an electric field that hinders the flow of charged ions through the channel. For example a negatively charged channel wall will result in negatively charged ions being forced to the centre of the channel where they will move faster than their positively charged colleagues which are attracted to the walls (because opposites attract). Over time this means a positive charge is built up at one end of the channel and a negative charge at the other – not unlike a battery! By wiring up the ends of the channel a (rather small) current can be produced. It needs some further work as the current is so small that it would take years to charge a mobile phone, but it is an interesting idea.
It is possible to generate electricity from estuaries where fresh water streams flow into the sea. This is known as salinity-gradient energy but thankfully is also referred to as blue energy. Blue energy can work either on the principle of osmosis (the movement of water from a low salt concentration to a high salt concentration) or electrodialysis (the movement of salt from a highly concentrated solution to a low concentrated solution) where the saline water and fresh water be separated by a selectively permeable membrane. In the osmosis process water pressure is created that can drive a turbine. In the electrodialysis case the movement of ions creates the electricity. The only by-product of blue energy is brackish water which would naturally occur in an estuary anyway. The global energy output from estuaries is estimated at 2.6TW, which represents a whopping 20% of the current worldwide energy demand. With figures like these it sounds rather exciting, but once again it is early days in the development of this technology and I think only a couple of test units exist in the Netherlands.
It is amazing what you can turn up when you look into a subject. Of these three topics, blue energy was the only one I had come across before this week. I’m sure if I looked a little harder I’d be able to find other interesting examples. It seems reassuring that there is so much work going into future low-carbon energy technologies. If only we could make better use of the ones available today…
[1] R. Guigon et al., Smart Mater. Struct., 17, (2008), 015038-9
[2] J. Yang et al., J. Micromech. Microeng., 13, (2003), 963
This week I have been inspired by water and energy, in fact specifically by a paper by French scientists [1] on harvesting energy from raindrops. In the authors own words “Our system recovers the vibration energy from a piezoelectric flexible structure impacted by a water drop”. What?!? Put more simply, some materials (in this case polyvinylidene fluoride) can convert mechanical energy into electrical energy. This is called the piezoelectric effect, and is similar to that which I described previously in power dressing. So as rain drops hit the material it generates an electrical current (naturally it’s a bit more complicated than this).
So how much power can you generate? The authors estimate that the available rain power in French regions with a continental climate to be almost 1 Wh per square metre per year. For comparison, in Scotland a south-facing roof receives between 700 - 1100 kWh/m2 of solar radiation during a year – oh dear. It’s probably a bit unfair to make this comparison now since this is very early in the development path of this technology. I also like this idea since I’m from the North West of England where it is very wet indeed.
This idea got me wondering about other novel ways in which water could be used to generate electricity. I thought it best to steer away from the classics such as watermills, hydroelectricity, wave and tidal power and generation of hydrogen through electrolysis or thermochemical methods. Instead I have dug out a couple of examples from the literature which interested me.
It appears that engineers at the University of Alberta in Canada have found that pumping water through microchannels in a glass disk can generate an electrical current [2]. In fact they claim “[that it is] the first new way to produce sustainable electricity in 160 years”.
How does it work? Forcing water through tiny glass channels is known to be tough because the channel walls become charged which creates an electric field that hinders the flow of charged ions through the channel. For example a negatively charged channel wall will result in negatively charged ions being forced to the centre of the channel where they will move faster than their positively charged colleagues which are attracted to the walls (because opposites attract). Over time this means a positive charge is built up at one end of the channel and a negative charge at the other – not unlike a battery! By wiring up the ends of the channel a (rather small) current can be produced. It needs some further work as the current is so small that it would take years to charge a mobile phone, but it is an interesting idea.
It is possible to generate electricity from estuaries where fresh water streams flow into the sea. This is known as salinity-gradient energy but thankfully is also referred to as blue energy. Blue energy can work either on the principle of osmosis (the movement of water from a low salt concentration to a high salt concentration) or electrodialysis (the movement of salt from a highly concentrated solution to a low concentrated solution) where the saline water and fresh water be separated by a selectively permeable membrane. In the osmosis process water pressure is created that can drive a turbine. In the electrodialysis case the movement of ions creates the electricity. The only by-product of blue energy is brackish water which would naturally occur in an estuary anyway. The global energy output from estuaries is estimated at 2.6TW, which represents a whopping 20% of the current worldwide energy demand. With figures like these it sounds rather exciting, but once again it is early days in the development of this technology and I think only a couple of test units exist in the Netherlands.
It is amazing what you can turn up when you look into a subject. Of these three topics, blue energy was the only one I had come across before this week. I’m sure if I looked a little harder I’d be able to find other interesting examples. It seems reassuring that there is so much work going into future low-carbon energy technologies. If only we could make better use of the ones available today…
[1] R. Guigon et al., Smart Mater. Struct., 17, (2008), 015038-9
[2] J. Yang et al., J. Micromech. Microeng., 13, (2003), 963
Thursday, 13 March 2008
Green Budget?
By Jeff Hardy
On Thursday we witnessed the first budget from Alistair Darling. How did you feel about it? I don’t think anyone was expecting anything dramatic as there isn’t really the wriggle room for big spending and grand gestures. It was built up as a green budget, and there were certainly some announcements relating to sustainable energy within it that were interesting.
Transport featured quite heavily. Gas guzzling cars (greater than 255 gCO2 per km labelled band M) took a bit of a hammering. Vehicle Excise Duty will be raised to £425 in 2009 and in 2010 you will also have a pay a one off cost of £950 when you buy such a car. Additionally, fuel duty will be raised by 2p per litre in October this year.
Biofuels have come under the policy microscope and sensibly the Government is looking to prioritise the most sustainable biofuels – although I’m not convinced that a sustainable biofuel has yet been defined anywhere. I’m also a little dubious of the table on carbon dioxide savings of biofuels compared to fossil fuels (page 98 of budget document) in light of recent studies examining land-use changes.
The aviation sector didn’t escape and the new per flight tax (replacing the per passenger tax) is to be increased by 10% in the second year of operation from whenever it starts – it’s under consultation currently.
New homes are to be zero carbon by 2016 and non-domestic buildings by 2019 according to the budget and this seems a worthy ambition. What I didn’t see, and perhaps I missed it, is any mention of measures to improve the energy efficiency of the existing housing stock. Without a major demolition programme the majority of houses in the UK in 2050 are already built. I’ll come back to this briefly later.
The humble plastic bag is to be phased out! Well, actually the plan is to put a cost (tax) on it so that we stop using it. Whilst I don’t think that this will halt climate change I’m glad that it has finally happened as it has proven successful elsewhere (see for example the Republic of Ireland). One caveat to my enthusiasm is that it’s important that this doesn’t have undesirable knock-on effects such as a switch by supermarkets to paper bags or something else. The idea should really be to encourage people to bring the means to carry their shopping home with them.
I want to comment on the proposed increase in winter fuel duty. I think that everyone should enjoy an affordable and comfortable home in winter (and indeed all year round). Is paying winter fuel duty every year the best way to achieve this or are there other ways to approach this? One thought would be to radically improve the insulation and efficiency of the heating systems in the homes of those at risk of fuel poverty (and in an ideal world, all homes). As a one off cost this is more expensive in a given year, but surely it would significantly reduce heating bills and must be cost effective in the long run? Energy efficient homes require less heating meaning lower heating bills, lower carbon dioxide emissions and ultimately reduced fuel poverty.
What do all these measures mean in terms of carbon emissions reductions? In all honesty, I have no idea! The environmental impacts of the measures are listed on page 107 of the Budget document. I was hoping to add them all up and present it as a lump of carbon dioxide savings. Unfortunately it’s not quite that straight forward as the ways in which the data are reported is not terribly helpful. If it helps then I think that there will be some reduction in carbon dioxide by 2020. Hopefully the very recently formed Committee on Climate Change, including UKERCs own Professor Jim Skea, will be able to help Government present these figures in a clearer and more transparent way.
So was it a green budget – does it put us clearly on a path towards significant carbon dioxide emissions reductions? No, not really. With just 11 more budgets before the Climate Change Bill 2020 target of a 26% carbon dioxide reduction, based on 1990 levels, we’ll need to see a much greater effort coming through. I think that the Committee on Climate Change will have a vital role in this and wish them good luck.
On Thursday we witnessed the first budget from Alistair Darling. How did you feel about it? I don’t think anyone was expecting anything dramatic as there isn’t really the wriggle room for big spending and grand gestures. It was built up as a green budget, and there were certainly some announcements relating to sustainable energy within it that were interesting.
Transport featured quite heavily. Gas guzzling cars (greater than 255 gCO2 per km labelled band M) took a bit of a hammering. Vehicle Excise Duty will be raised to £425 in 2009 and in 2010 you will also have a pay a one off cost of £950 when you buy such a car. Additionally, fuel duty will be raised by 2p per litre in October this year.
Biofuels have come under the policy microscope and sensibly the Government is looking to prioritise the most sustainable biofuels – although I’m not convinced that a sustainable biofuel has yet been defined anywhere. I’m also a little dubious of the table on carbon dioxide savings of biofuels compared to fossil fuels (page 98 of budget document) in light of recent studies examining land-use changes.
The aviation sector didn’t escape and the new per flight tax (replacing the per passenger tax) is to be increased by 10% in the second year of operation from whenever it starts – it’s under consultation currently.
New homes are to be zero carbon by 2016 and non-domestic buildings by 2019 according to the budget and this seems a worthy ambition. What I didn’t see, and perhaps I missed it, is any mention of measures to improve the energy efficiency of the existing housing stock. Without a major demolition programme the majority of houses in the UK in 2050 are already built. I’ll come back to this briefly later.
The humble plastic bag is to be phased out! Well, actually the plan is to put a cost (tax) on it so that we stop using it. Whilst I don’t think that this will halt climate change I’m glad that it has finally happened as it has proven successful elsewhere (see for example the Republic of Ireland). One caveat to my enthusiasm is that it’s important that this doesn’t have undesirable knock-on effects such as a switch by supermarkets to paper bags or something else. The idea should really be to encourage people to bring the means to carry their shopping home with them.
I want to comment on the proposed increase in winter fuel duty. I think that everyone should enjoy an affordable and comfortable home in winter (and indeed all year round). Is paying winter fuel duty every year the best way to achieve this or are there other ways to approach this? One thought would be to radically improve the insulation and efficiency of the heating systems in the homes of those at risk of fuel poverty (and in an ideal world, all homes). As a one off cost this is more expensive in a given year, but surely it would significantly reduce heating bills and must be cost effective in the long run? Energy efficient homes require less heating meaning lower heating bills, lower carbon dioxide emissions and ultimately reduced fuel poverty.
What do all these measures mean in terms of carbon emissions reductions? In all honesty, I have no idea! The environmental impacts of the measures are listed on page 107 of the Budget document. I was hoping to add them all up and present it as a lump of carbon dioxide savings. Unfortunately it’s not quite that straight forward as the ways in which the data are reported is not terribly helpful. If it helps then I think that there will be some reduction in carbon dioxide by 2020. Hopefully the very recently formed Committee on Climate Change, including UKERCs own Professor Jim Skea, will be able to help Government present these figures in a clearer and more transparent way.
So was it a green budget – does it put us clearly on a path towards significant carbon dioxide emissions reductions? No, not really. With just 11 more budgets before the Climate Change Bill 2020 target of a 26% carbon dioxide reduction, based on 1990 levels, we’ll need to see a much greater effort coming through. I think that the Committee on Climate Change will have a vital role in this and wish them good luck.
Thursday, 6 March 2008
Power dressing - Jeff Hardy
Is it just me or are there more and more unusual energy related technologies getting into the popular media in recent times? Perhaps it's just a function of my daily news trawl for the National Energy Research Network, but several things have surprised me recently.
It appears that scientists and engineers have been busily devising ways of usefully capturing some of the energy we expend whilst wandering around. The driving force, perhaps unsurprisingly, is the need to charge electronic devices away from the grid – I suspect particularly by the military.
In its simplest incarnation, the idea is to turn us into mobile solar power platforms. For example, backpacks fitted with solar photovoltaic cells and lithium ion batteries are already available. These mainly provide power for mobile phones and other small electronic devices on the move. PV cells are also being fitted to other things, including laptops and mobile phones.
Scientists in Canada and America have developed a knee brace that captures the kinetic energy of walking. The device works in a similar way to regenerative braking in hybrid electric and can generate around 5 watts of electricity at a typical walking pace. This is approximately enough to charge 10 mobile phones simultaneously. It looks like a rather sturdy knee support and currently weighs in at a rather hefty 1.6 kg; however it is a work in progress. The device could potentially be built into prosthetic knees, or other such implants, which could negate the need for further surgery to replace batteries that these devices require.
Not to be outdone, nanotechnologists in America are proposing to make clothes from nanofibres that generate electricity from movement, literally opening the door for power dressing. The technology works through the piezoelectric effect, which converts mechanical energy to electrical energy. The electrical energy is generated when pairs of zinc oxide fibres (one of which has been coated in gold to act as an electrode) rub together. The inventors estimate that up to 80 milliwatts of electricity could be generated per square metre of fabric, which is about enough to power an iPod.
An idea struck me when I was writing this article. I use the gym frequently (although not as frequently as I should…) and I spent a lot of time rowing, cycling and running. Could I be putting all this kinetic energy to use by converting it into electrical energy? Unless you are a genius, then any idea that you have thought of will already have been explored (and then probably rubbished/exploited) by someone else. A quick internet trawl proved this to be the case. The answer to the question is a resounding "sort of". I'll not go into the full details as you can read them for yourself, but in essence, my 10 minute slog on the rowing machine equates very roughly to enough energy to run a light bulb for 30 minutes. I can assure you that it feels like more work than that.
This idea has actually been brought into reality in a Hong Kong gym. Here they reckon that the average person produces around 50 watts of electricity per hour of exercise. They harness this by placing a generator in the machine and storing the electrical energy generated in batteries. The electricity is used to contribute to the gyms lighting and apparently inspires the members to push themselves harder knowing that their efforts are not wasted.
So, will we see people plugging themselves into the grid to sell their daily harvest of electricity anytime soon? Probably not, but it's fascinating to see the ways in which scientists and engineers are approaching energy generation and also that that these inventions are being picked up by the popular press. Is this just a function of energy being such a media buzz word at present or is it an indication that more and more bright minded people are rising to the energy challenge in a variety of novel and unexpected ways?
It appears that scientists and engineers have been busily devising ways of usefully capturing some of the energy we expend whilst wandering around. The driving force, perhaps unsurprisingly, is the need to charge electronic devices away from the grid – I suspect particularly by the military.
In its simplest incarnation, the idea is to turn us into mobile solar power platforms. For example, backpacks fitted with solar photovoltaic cells and lithium ion batteries are already available. These mainly provide power for mobile phones and other small electronic devices on the move. PV cells are also being fitted to other things, including laptops and mobile phones.
Scientists in Canada and America have developed a knee brace that captures the kinetic energy of walking. The device works in a similar way to regenerative braking in hybrid electric and can generate around 5 watts of electricity at a typical walking pace. This is approximately enough to charge 10 mobile phones simultaneously. It looks like a rather sturdy knee support and currently weighs in at a rather hefty 1.6 kg; however it is a work in progress. The device could potentially be built into prosthetic knees, or other such implants, which could negate the need for further surgery to replace batteries that these devices require.
Not to be outdone, nanotechnologists in America are proposing to make clothes from nanofibres that generate electricity from movement, literally opening the door for power dressing. The technology works through the piezoelectric effect, which converts mechanical energy to electrical energy. The electrical energy is generated when pairs of zinc oxide fibres (one of which has been coated in gold to act as an electrode) rub together. The inventors estimate that up to 80 milliwatts of electricity could be generated per square metre of fabric, which is about enough to power an iPod.
An idea struck me when I was writing this article. I use the gym frequently (although not as frequently as I should…) and I spent a lot of time rowing, cycling and running. Could I be putting all this kinetic energy to use by converting it into electrical energy? Unless you are a genius, then any idea that you have thought of will already have been explored (and then probably rubbished/exploited) by someone else. A quick internet trawl proved this to be the case. The answer to the question is a resounding "sort of". I'll not go into the full details as you can read them for yourself, but in essence, my 10 minute slog on the rowing machine equates very roughly to enough energy to run a light bulb for 30 minutes. I can assure you that it feels like more work than that.
This idea has actually been brought into reality in a Hong Kong gym. Here they reckon that the average person produces around 50 watts of electricity per hour of exercise. They harness this by placing a generator in the machine and storing the electrical energy generated in batteries. The electricity is used to contribute to the gyms lighting and apparently inspires the members to push themselves harder knowing that their efforts are not wasted.
So, will we see people plugging themselves into the grid to sell their daily harvest of electricity anytime soon? Probably not, but it's fascinating to see the ways in which scientists and engineers are approaching energy generation and also that that these inventions are being picked up by the popular press. Is this just a function of energy being such a media buzz word at present or is it an indication that more and more bright minded people are rising to the energy challenge in a variety of novel and unexpected ways?
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