A new microbe-powered device can extract up to 99% of the available hydrogen from biological compounds that have stumped previous attempts to ferment fuel from plant waste. The secret is to give the bugs a helping hand with a kick of electric charge.
Hydrogen is an attractive environmentally friendly fuel because burning it creates only water as a waste product. But finding an efficient, clean way to produce hydrogen in the first place is difficult.
Fermenting organic material using microbes is one possibility, but generally produces poor yields. Microbes reach a chemical dead end once sugar from material has been broken down into acetic acid, carbon dioxide and hydrogen. That releases at best only a third of the hydrogen in a molecule of the sugar glucose, for example.
"There is no known biological route to ferment glucose to [get] any more hydrogen than that," says Bruce Logan of Pennsylvania State University in University Park, US, who with colleague Shaoan Cheng has demonstrated a way around that the problem.
Reversed process
Their microbial electrolysis cells (MECs) enable microbes to break down organic materials completely, to just water, carbon dioxide, and hydrogen. The latest design can release as much as 99% of the hydrogen in acetic acid, a common dead end to fermentation.
MECs are modified versions of microbial fuel cells, which are used to harvest electrons produced by metabolising microbes as they feed to generate electricity. The electrochemical reactions are balanced when the used electrons are combined oxygen and hydrogen ions also released by the microbes to form water.
Logan's MECs are like microbial fuel cells in reverse. Instead of charge being drawn out, it is pumped in, and the hydrogen ions combine with electrons alone to form hydrogen gas. Applying roughly 0.5 volts provides enough energy to drive thermodynamically unlikely chemical reactions that break down the dead-end products that limited previous attempts to ferment hydrogen.
MECs can also break down other by-products of fermentation that put an end to the process, such as lactic, valeric, and butyric acids, says Logan. In tests it was fed cellulose and glucose and broke them down completely without problems.
'Great news'
The researchers were able to generate up to 1.23 cubic meters of hydrogen per day for every cubic meter of hydrogen fuel cell. This rate of hydrogen production is about 275 times faster than their earlier MEC.
In tests, the system produced hydrogen that, if fed into a hydrogen fuel cell that was 50% efficient, could generate between 1.2 and 3.4 times as much electricity as was fed into the system. By comparison, hydrogen extracted from water can only pay back about 25 to 30% of the energy used to extract it.
"It is surprising that such high hydrogen yields can so readily be obtained," says Patrick Hallenbeck of the University of Montreal in Canada. "The net energy yield appears much higher than what people are getting in other biofuel production processes – bioethanol, for example," he adds.
But the process is still much too slow to be practical, Hallenbeck adds. Logan and colleagues are currently working on improving the speed. The performance of the MECs exceeded the expectations of Lars Angenent, of Washington University in St. Louis, Missouri, US, who is also interested in using microbes to make fuel. "This is great news," he says.
Mason Inman
full article
Wednesday, 14 November 2007
Tuesday, 13 November 2007
Using dishwasher at night 'could cut bills'
Householders could benefit from reduced energy bills if they agree to run their washing machines, tumble dryers and dishwashers in the middle of the night.
The proposal is part of a £6 billion British Gas plan, backed by rival energy companies, to change the way people use their appliances and run their gas meters.
The company calculated that if people used their tumble dryers, washing machines and other energy-hungry appliances in the middle of the night, it could save 1,000 megawatts or almost two per cent of the country's total energy usage.
This is because, in effect, it takes two power stations simply to cope with the surge at peak times, such as 6pm - when people come home from work, turn on the television and oven and put on a load of washing.
British Gas and the other companies want to offer consumers a more sophisticated version of Economy Seven, a tariff pioneered in the 1980s that is still popular.
Economy Seven gives householders a discount for running their boiler in the middle of the night. Energy companies could offer similar discounts to customers for using appliances during late mornings or mid-afternoon, when most people are at work.
However, they could offer these discount schemes only if the Government approves so-called "smart meters" to replace existing gas and electricity meters.
These would allow the energy companies to more closely monitor how much energy each family is using, and scrap the need for a meter reader to call at homes.
Instead the reading would be sent electronically to the organisation's headquarters.
This should save the companies millions of pounds - enough, they say, to eventually fund the £6 billion needed to provide the meters without consumers having to pay a penny.
The Department for Business, Enterprise and Regulatory Reform is in favour of the scheme but has yet to agree with Ofgem, the industry regulator, how to make the meters available across the country at minimal cost.
As part of the plan to persuade the Government to approve the scheme, British Gas has commissioned research to show how much energy could be saved by people using their appliances at off-peak times of the day.
It estimated that smart metering could save each household £2.50 per year. Those opting for an off-peak tariff should enjoy far greater savings.
Any pricing, however, has yet to be decided as the meters are not likely to be introduced until 2010 at the earliest.
There are fears that if different companies, British Gas and Powergen, for example, installed meters in the same area, the cost of each sending an engineer to the same street could wipe out any saving to consumers.
A British Gas spokesman said: "This is our chance to really revolutionise the metering industry.
"If it is done properly, it could give the UK billions of pounds of benefits through cuts in energy use and better customer service."
By Harry Wallop
full article
The proposal is part of a £6 billion British Gas plan, backed by rival energy companies, to change the way people use their appliances and run their gas meters.
The company calculated that if people used their tumble dryers, washing machines and other energy-hungry appliances in the middle of the night, it could save 1,000 megawatts or almost two per cent of the country's total energy usage.
This is because, in effect, it takes two power stations simply to cope with the surge at peak times, such as 6pm - when people come home from work, turn on the television and oven and put on a load of washing.
British Gas and the other companies want to offer consumers a more sophisticated version of Economy Seven, a tariff pioneered in the 1980s that is still popular.
Economy Seven gives householders a discount for running their boiler in the middle of the night. Energy companies could offer similar discounts to customers for using appliances during late mornings or mid-afternoon, when most people are at work.
However, they could offer these discount schemes only if the Government approves so-called "smart meters" to replace existing gas and electricity meters.
These would allow the energy companies to more closely monitor how much energy each family is using, and scrap the need for a meter reader to call at homes.
Instead the reading would be sent electronically to the organisation's headquarters.
This should save the companies millions of pounds - enough, they say, to eventually fund the £6 billion needed to provide the meters without consumers having to pay a penny.
The Department for Business, Enterprise and Regulatory Reform is in favour of the scheme but has yet to agree with Ofgem, the industry regulator, how to make the meters available across the country at minimal cost.
As part of the plan to persuade the Government to approve the scheme, British Gas has commissioned research to show how much energy could be saved by people using their appliances at off-peak times of the day.
It estimated that smart metering could save each household £2.50 per year. Those opting for an off-peak tariff should enjoy far greater savings.
Any pricing, however, has yet to be decided as the meters are not likely to be introduced until 2010 at the earliest.
There are fears that if different companies, British Gas and Powergen, for example, installed meters in the same area, the cost of each sending an engineer to the same street could wipe out any saving to consumers.
A British Gas spokesman said: "This is our chance to really revolutionise the metering industry.
"If it is done properly, it could give the UK billions of pounds of benefits through cuts in energy use and better customer service."
By Harry Wallop
full article
Monday, 12 November 2007
Home green home
IT IS a quiet and picturesque parish in the Scottish Borders, but Ayton is on the cusp of a revolution in the way renewable energy can be used to run our homes.
Building work begins today on the town's Beanburn Road, to create what it is believed will be Europe's first hydrogen-fuelled, zero-carbon home.
It will be the house of the future - a home completely independent from the national grid, which will make Scotland a worldwide centre for excellence in renewables. It will be equipped with a wind turbine and solar cell and generate hydrogen from water.
Berwickshire Housing Association (BHA), which is behind the project, thinks it is the first of its kind in Europe and says it will make Scotland a world leader in the renewables industry.
The pilot will be in social housing, with a family recruited to live in it before it is completed in March 2008, but if the technology proves successful it could be rolled out to private homes
The scheme will see a photovoltaic - or solar power - system added to the house, along with a wind turbine. The energy produced by these will be used to electrolyse water to split it into oxygen and hydrogen.
The hydrogen will be stored in underground tanks - each of which will be capable of producing a month's worth of electricity and heat.
"In effect, you end up with a power station within the home," said Mr Brown.
LINDSAY MCINTOSH
full article
Building work begins today on the town's Beanburn Road, to create what it is believed will be Europe's first hydrogen-fuelled, zero-carbon home.
It will be the house of the future - a home completely independent from the national grid, which will make Scotland a worldwide centre for excellence in renewables. It will be equipped with a wind turbine and solar cell and generate hydrogen from water.
Berwickshire Housing Association (BHA), which is behind the project, thinks it is the first of its kind in Europe and says it will make Scotland a world leader in the renewables industry.
The pilot will be in social housing, with a family recruited to live in it before it is completed in March 2008, but if the technology proves successful it could be rolled out to private homes
The scheme will see a photovoltaic - or solar power - system added to the house, along with a wind turbine. The energy produced by these will be used to electrolyse water to split it into oxygen and hydrogen.
The hydrogen will be stored in underground tanks - each of which will be capable of producing a month's worth of electricity and heat.
"In effect, you end up with a power station within the home," said Mr Brown.
LINDSAY MCINTOSH
full article
Sunday, 11 November 2007
The green home goes underground
BEETLEBANK, Earwig Green, does not sound the most attractive of addresses. But down a narrow, hedge-lined lane in the Weald of Kent, where half-timbered, tile-hung cottages and converted oast houses are the norm, is a stunning modern home of yellow brick, green oak, plate glass and slabs of crystalline schist rock... with a view down the upper Medway valley, with woods, fields grazed by cows, and the stately pile of Penshurst Place beyond.
“We are so lucky to live in this wonderful valley,” says the owner, John Morrison. John and his wife Helen, both 58, have just moved in after 18 months of building work overseen by their son, Robert, who acted as project manager.
It is not the first home on this site. The previous house was a wooden Red Cross first-aid hut, erected in the First World War, that had been added to over the years. “When the wind blew, there were so many holes in it that the building whistled,” says Robert, aged 31. “It was a pull-down job and start from scratch.” And what a scratch it was – 7m (23ft) deep, served by three trenches for geothermal heating that were 50m long and 1.8m deep.
“The earth below the frost line remains at a relatively constant temperature, which equates roughly to the average annual air temperature,” says Robert, who trained as an oceanographer. “Here that is 12C (53F). The trenches contain pipes in the form of loops that bring the water and antifreeze solution out and back to the house. A heat exchanger in the house heats the water for two storage tanks, one to service the underfloor heating pipes and one to provide hot water for the kitchen and bathrooms. Each night, Economy 7 electricity is used to heat the water to 60C or 65C, to prevent legionnaires’ disease, but by the time the showers are used in the day the hot water temperature will be around 40C, about right for a shower.”
Beetlebank is in an Area of Outstanding Natural Beauty, so planning procedures meant that it was two years before the diggers were on site, in March 2006. “To get the living area my parents wanted,” Robert says, “we had to go into the ground; there are an awful lot of unknowns when you do that.”
Beetlebank is a lightweight steel structure with living space half above ground, half below. A central atrium brings light into the section below ground, which has a utility room, bedroom, media room, and an indoor pool and sauna full of natural light, supplemented by 100 low-energy LED lights. The pool has an underwater speaker. A cine-system can project TV or films on the wall. At ground level the living room has floor-to-ceiling glass doors that open onto a west-facing patio. The east side is all glass with a view towards Penshurst. There is an open fireplace on the north wall. The kitchen is open plan. On the south side of the atrium is the master bedroom with more great views. Another bedroom overlooks a water feature in the patio, across which is a two-man office.
Throughout, the flooring is of natural stone – crystalline oyster schist containing natural colours of blue and muted reds, with sparkling patches of fool’s gold. The same stone is used for the adjoining patio areas. If you walk over this flooring in bare or stockinged feet, you can feel the warmth rising up.
Find out how to build your own green home at timesonline.co.uk/greenhouse
FACTFILE
Most homes require a heating load of 8kW to 12kW. Installation costs about £1,000 per kW. Recouping the investment takes about ten years.
Ground-source heating systems can cut costs by 35 to 75 per cent, carbon dioxide emissions by 40 to 60 per cent, compared with a traditional fossil system.
The geothermal heating system for Beetlebank was designed by EarthEnergy, 01326 310650, www.earthenergy.co.uk . Robert Morrison: 020-7738 1557.
full article
“We are so lucky to live in this wonderful valley,” says the owner, John Morrison. John and his wife Helen, both 58, have just moved in after 18 months of building work overseen by their son, Robert, who acted as project manager.
It is not the first home on this site. The previous house was a wooden Red Cross first-aid hut, erected in the First World War, that had been added to over the years. “When the wind blew, there were so many holes in it that the building whistled,” says Robert, aged 31. “It was a pull-down job and start from scratch.” And what a scratch it was – 7m (23ft) deep, served by three trenches for geothermal heating that were 50m long and 1.8m deep.
“The earth below the frost line remains at a relatively constant temperature, which equates roughly to the average annual air temperature,” says Robert, who trained as an oceanographer. “Here that is 12C (53F). The trenches contain pipes in the form of loops that bring the water and antifreeze solution out and back to the house. A heat exchanger in the house heats the water for two storage tanks, one to service the underfloor heating pipes and one to provide hot water for the kitchen and bathrooms. Each night, Economy 7 electricity is used to heat the water to 60C or 65C, to prevent legionnaires’ disease, but by the time the showers are used in the day the hot water temperature will be around 40C, about right for a shower.”
Beetlebank is in an Area of Outstanding Natural Beauty, so planning procedures meant that it was two years before the diggers were on site, in March 2006. “To get the living area my parents wanted,” Robert says, “we had to go into the ground; there are an awful lot of unknowns when you do that.”
Beetlebank is a lightweight steel structure with living space half above ground, half below. A central atrium brings light into the section below ground, which has a utility room, bedroom, media room, and an indoor pool and sauna full of natural light, supplemented by 100 low-energy LED lights. The pool has an underwater speaker. A cine-system can project TV or films on the wall. At ground level the living room has floor-to-ceiling glass doors that open onto a west-facing patio. The east side is all glass with a view towards Penshurst. There is an open fireplace on the north wall. The kitchen is open plan. On the south side of the atrium is the master bedroom with more great views. Another bedroom overlooks a water feature in the patio, across which is a two-man office.
Throughout, the flooring is of natural stone – crystalline oyster schist containing natural colours of blue and muted reds, with sparkling patches of fool’s gold. The same stone is used for the adjoining patio areas. If you walk over this flooring in bare or stockinged feet, you can feel the warmth rising up.
Find out how to build your own green home at timesonline.co.uk/greenhouse
FACTFILE
Most homes require a heating load of 8kW to 12kW. Installation costs about £1,000 per kW. Recouping the investment takes about ten years.
Ground-source heating systems can cut costs by 35 to 75 per cent, carbon dioxide emissions by 40 to 60 per cent, compared with a traditional fossil system.
The geothermal heating system for Beetlebank was designed by EarthEnergy, 01326 310650, www.earthenergy.co.uk . Robert Morrison: 020-7738 1557.
full article
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