Category: Archive

Household energy use

The figures on household energy use I have referred to in this book come from the Australian Greenhouse office. The key figures are summarised in the table below and provide a quick way to estimate the impact of the various components employed in the average household.

More detailed figures are available at greenhouse.gov.au Note that these figures are per household, rather than per person.

These figures consider the energy consumption in running the home, not in building it or in the appliances that we purchase. Buying a new solar hot water service eliminates the 3 tonnes of carbon dioxide equivalent used to heat water, but greenhouse gases have been generated by manufacturing and installing the unit. These emission figures are generally assigned to industry, rather than domestic use. The article on embedded energy at the end of chapter one explains this concept in more detail. Because of this it is best to buy new appliances when old ones wear out.

Replacing an electric or gas hot water service with a solar one immediately eliminates 3 tonnes of CO2 each year. This is the easiest challenge to tackle. Reducing your driving is the next easiest thing to address, and also has an immediate effect. As well, it has the advantage of not requiring any new appliance. If you assume about 5tonnes of CO2 per car per year, you can see the value of doing without a second car. Renting cars on those occasions where you need two cars may be more cost effective as well as more energy efficient.

Replacing existing appliances with energy efficient appliances can significantly reduce energy consumption but using them less will have a much greater impact. Consider seriously whether you need new appliances at all. Some appliances – a rice cooker or bread maker, for example – may contribute to a more sustainable lifestyle as well as energy efficiency. This may offset the energy cost of producing the appliance.

Estimating specific emissions

The figures for average usage give an overview of where you might make major savings. If you want to estimate more accurately the contribution any particular appliance or activity makes to global warming – energy use, the following table is more specific. For some activities, different options offer different levels of accuracy. These remain rough estimates, based on a wide range of assumption.

Domestic heating and cooling

Changing the way you heat and cool your home can clearly make a significant contribution. Again, a change in your habits is more effective than buying a new appliance. If you are building or renovating, however, this will be one of the most significant contributions you can make.

The table below from the Sustainable Energy Development Office of Western Australia (http://www1.sedo.energy.wa.gov.au/pages/heat_run.asp) rates the energy consumption of various approaches to heating. The figures will be slightly different for NSW, because of differences in the relative cost of different sources of energy. I have invited the NSW greenhouse office to provide similar figures for residents of Sydney.

• Range for central and space heaters is from most efficient to least efficient models known to be available. This is little variation in efficiencies of portable heaters
• The more natural gas appliances used, the lower the natural gas price and the less the heater will cost to run.
• Note Electric heaters which use NaturalPower instead of conventional electricity will have no greenhouse gas emissions, but will cost more to run. If wood is sustainably grown the fuel is greenhouse neutral. However wood fires still cause pollution.

Measuring energy

We instinctively know what energy is. When we have a lot of energy we bounce around, energetically. When we light a fire under a kettle, the energy of the fire heats the water. If we use the steam to drive a steam engine, we can do useful work: Lifting an object, driving a train, running a factory. Work is what we do with energy.

Energy is measured in joules. One joule of energy will accelerate one kilogram of stuff by one meter per second for every second that it is applied. To hold up a kilogram of apples against the earth’s gravitational field consumes 10 joules of energy every second.

If we carry around a kilogram of apples we burn those 10 joules of energy every second. The rate at which we use energy is called power. Power is measured in watts. One watt is one joule each second. Carrying the bag of apples requires ten watts of power. Carrying the bag for one hour uses one watt hour of energy. Another way of saying that is that it used 36,000 joules or 36 kilojoules.

A 100 watt light globe, then, uses as much energy as holding up a 10 kilogram bag of apples against the earth’s gravity. Doing it for an hour uses 100watthours, or 36kilojoules.

We pay around 15c per kilowatt hour for electricity. Look at your electricity bill to get a more accurate calculation.

If your electricity bill is $300 per quarter, you are using around 2,000 kilowatt hours of electricity each quarter, that is 8,000 kilowatt hours of energy each year. This is also called 8Megawatt hours. That is equivalent to 28,800 megajoules, also known as 28.8Gigajoules.

Energy comes from burning fuel. The energy value of food is measured in Calories. To do a good day’s work, the human body needs at least 2000Calories of food each day. One Calorie is equal to 4,187 Joules. The energy in a day’s food is over 8 megajoules. The human being is not a terribly efficient machine.

The energy content of petroleum, by comparison, is enormous. One litre of fuel oil packs 40Megajoules of energy. That is the equivalent energy of five days worth of food. A barrel of oil holds about 6000 litres of fuel. When you consider that the world uses over 80 million barrels of oil each day, you can start to see the scale of the energy challenges we currently face.

The following table lists various units of energy that you will encounter, and the conversion rates between them.

There are also hundreds of online conversion tools to convert instantly between any range of energy units. These examples are fairly typical

http://www.chemlink.com.au/conversions.htm

http://www.convert-me.com/en/convert/energy

http://www.unitconversion.org/unit_converter/energy.html

Energy and greenhouse gases

The biggest cause of global warming is the amount of carbon dioxide in the air.

To calculate the amount of carbon dioxide you produce I have used the following conversion factors.

Obviously these figures are approximations that depend on a range of factors. The analysis below explains how these figures have been arrived at.

The generation of electricity produces greenhouse gas through the burning of coal and other fuel. Burning coal, for example, produces more greenhouse gas than natural gas. Hydroelectricity produces very little greenhouse gas. The actual process of capturing energy from falling water and using it to turn a turbine produces no greenhouse gas, but some emissions are created by the cars, trucks and other machines used by the hydroelectricity companies.

The amount of greenhouse gas produced by your electricity use depends on the way it is generated. In Sydney, one megawatt hour of electricity produces about 985kilograms of carbon dioxide equivalent. Throughout this book I have rounded this to one tonne of CO₂ per Megawatt hour. In Tasmania, the number is closer to 30kilograms because of the predominance of hydro electricity.

Carbon dioxide is not the only greenhouse gas – other greenhouse gases also trap the sun’s energy. Methane, for example, is a more effective greenhouse gas than carbon dioxide. Methane is the active ingredient in natural gas and is a byproduct of digestion, and the decomposition of food and other rubbish.

The amount of greenhouse gas that any country, industry, or household produces is measured in tonnes (or kilograms) of Carbon Dioxide equivalent. If a process produces one tonne of carbon dioxide equivalent, it has the same effect that one tonne of carbon dioxide would.

It may be useful to know that one tonne of coal produces over three tonnes of carbon dioxide equivalent. High quality coal is basically pure carbon. If it is burned efficiently, that carbon is burned with very little pollution and is totally converted to carbon dioxide. Every carbon atom combines with two oxygen atoms to produce a molecule of carbon dioxide. Oxygen is 14% heavier than carbon, so one tonne of high quality coal produces 3.28 tonnes of carbon dioxide. Low quality coal produces a mixture of pollutants, including oxides of sulphur and nitrogen which are greenhouse gases as well as causing acid rain and other problems.

The UltraBattery also has the ability to provide and absorb charge rapidly during vehicle acceleration and braking, making it particularly suitable for HEVs, which rely on the electric motor to meet peak power needs during acceleration and can recapture energy normally wasted through braking to recharge the battery.

Over the past 12 months, a team of drivers has put the UltraBattery to the test at the Millbrook Proving Ground in the United Kingdom, one of Europe’s leading locations for the development and demonstration of land vehicles.

“Passing the 100,000 miles mark is strong evidence of the UltraBattery’s capabilities,” Mr Lamb said.
 “CSIRO’s ongoing research will further improve the technology’s capabilities, making it lighter, more efficient and capable of setting new performance standards for HEVs.”

The UltraBattery test program for HEV applications is the result of an international collaboration. The battery system was developed by CSIRO in Australia, built by the Furukawa Battery Company of Japan and tested in the United Kingdom through the American-based Advanced Lead-Acid Battery Consortium.

UltraBattery technology also has applications for renewable energy storage from wind and solar. CSIRO is part of a technology start-up that will develop and commercialise battery-based storage solutions for these energy sources.

The joint USDA-ARS and Institute of Agriculture and Natural Resources study also found greenhouse gas emissions from cellulosic ethanol made from switchgrass were 94 percent lower than estimated greenhouse gas emissions from gasoline production.

In a biorefinery, switchgrass biomass can be broken down into sugars including glucose and xylose that can be fermented into ethanol similar to corn. Grain from corn and other annual cereal grains, such as sorghum, are now primary sources for U.S. ethanol production.

In the future, perennial crops, such as switchgrass, as well as crop residues and forestry biomass could be developed as major cellulosic ethanol sources that could potentially displace 30 percent of current U.S. petroleum consumption, Vogel said. Technology to convert biomass into cellulosic ethanol is being developed and is now at the development stage where small commercial scale biorefineries are beginning to be built with scale-up support from the U.S. Department of Energy.

This study involved 10 fields of 15- to 20-acres each. Trials began in 2000 and 2001 and continued for five years. Farmers were paid for their work under contract with UNL and documented all production operations, agricultural inputs and biomass yields. The researchers used this information to determine the net energy estimates.

Switchgrass grown in this study yielded 93 percent more biomass per acre and an estimated 93 percent more net energy yield than previously estimated in a study done elsewhere of planted prairies in Minnesota that received low agricultural inputs, Vogel said. The study demonstrates that biomass energy from perennial bioenergy crops such as switchgrass can produce significantly more energy per acre than low input systems. Less land will be needed for energy crops if higher yields can be obtained.

Researchers point out in their study that plant biomass remaining after ethanol production could be used to provide the energy needed for the distilling process and other power requirements of the biorefinery. This results in a high net energy value for ethanol produced from switchgrass biomass. In contrast, corn grain ethanol biorefineries need to use natural gas or other sources of energy for the conversion process.

In this study, switchgrass managed as a bioenergy crop produced estimated ethanol yields per acre similar to those from corn grown in the same states and years based on statewide average grain yields.

"However, caution should be used in making direct ethanol yield comparisons with cellulosic sources and corn grains because corn grain conversion technology is mature, whereas cellulosic conversion efficiency technology is based on an estimated value," Vogel said.

Vogel said that he does not expect switchgrass to replace corn or other crops on Class 1 farm land. He and his colleagues are developing it for use on marginal, highly erodible lands similar to that currently in the Conservation Reserve Programs. All the fields in this study met the criteria that would have qualified for this program. Using a conservation cellulosic conversion value, researchers found that switchgrass grown on the marginal fields produced an average of 300 gallons of ethanol per acre compared to average ethanol yields of 350 gallons per acre for corn for the same three states.

The researchers point out that this was a base-line study. The switchgrass cultivars used in this study were developed for use in pastures. New higher yielding cultivars are under development for specific use in bioenergy production systems.

Switchgrass yields continue to improve, Vogel said. Recent yield trials of new experimental stains in the three states produced 50 percent higher yields than achieved in this study.

"Now, we really need to use an Extension effort to let farmers know about this new crop," Vogel said.

Future research will include further studies of improving management practices including work on improving establishment and harvesting methods, improving biomass yield, and improving conversion efficiency and net and total energy yields, Vogel said.

Switchgrass in this study employed UNL’s best management practices for switchgrass, including no-till seeding, herbicides, weed control and adaptive cultivars. This study was also based on farm fields up to 20 acres instead of smaller research-scale plots typically less than about 100 square feet.

Six cellulosic biorefineries that are being co-funded by the U.S. Department of Energy also are in the works across the U.S. that should be completed over the next few years. These plants are expected to produce more than 130 million gallons of cellulosic ethanol per year, according to the U.S. Department of Energy.

“It is obvious that strategic planning for wetland rehabilitation and long term protection of impacted ecosystems is a priority. The Minister for Primary Industries and the Government have known about these conditions for years. The environment, professional fishermen, recreational anglers and tourism industries will be severely impacted without long term management.

“Local conservationists have been campaigning for years for improvements in land use management after approximately 150 years of extremely high levels of ecosystem modification including clearance, cropping, drainage, artificial floodgates and burning. The pre-European Richmond River floodplain had a very high biomass of standing vegetation that provided what we are increasingly recognising as an ‘essential ecological service’ – that is the remediation, organic buffering and filtration of poor quality flood waters.

“Restoring forested wetlands on the floodplains will not only help clean up floodwaters, but will store and capture carbon and will also lead to long term stability for the river based fishing industry.

“Unfortunately climate change looks set to deliver greater volumes of water to the north coast. This will only increase pressure on the river and wetland ecology and should prompt the Government to act.

“It’s a bitter irony for the professional fishermen that they are classed as ‘harvesters’ and not ‘primary producers’, and therefore are not eligible for low interest loans under the Natural Disaster Relief Scheme, while the primary producers changing the floodplain are.

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