Feb 2, 2014 Energy Talks
The burning of fossil fuels such as coal, oil and natural gas to generate electricity releases carbon dioxide and other pollutants into the atmosphere.
Carbon dioxide is a greenhouse gas and is one of the constituents causing abnormal climatic changes and global warming. Global warming is a phenomenon of the gradual rise of the global average air temperature at the earth’s surface, due to increased insulating effect by the greenhouse gases in upper atmosphere preventing heat dissipation at the usual rate. The consequence of global warming has far-reaching impacts on our ecosystems, affecting agricultural production, and causing rise of sea level.
The burning of fossil fuels also generates atmospheric pollutants such as sulphur dioxide (SO2), nitrogen oxides (NOX), respiratory suspended particulates (RSPs), etc. Increased level of air pollutants will affect human health, with particular adverse effect on the young and the aged, as well as people with chronic health problems. Exposure to SO2 and NOX may cause impairment of respiratory functions and aggravate existing respiratory and cardiac illnesses. Similarly, RSPs are harmful to the respiratory system and at higher levels it can increase morbidity and mortality rates.
On the other hand, the fossil fuel reserves on earth have their limits. Fossil fuels, in their crude forms, are found below the earth’s crust, where they were formed under immense pressure from the remains of plants and animals in the pre-historic era. Over the past decades, human activities in pursuit of energy supply have resulted in the rapid depletion of these limited natural resources.
The shortage of fossil fuels in the not-too-distant future could seriously affect the activities of all walks of lives and impede economic development, and could eventually cause a global degradation of living standard to every economy. The development of renewable energy technologies has become one of the prerequisites in ensuring a sustainable future for mankind.
Jan 9, 2014 Sponge
An impressive idea is out in the International Journal of Energy Research from the University of Leeds and the Chinese Academy of Sciences. The research group has invented a new way to answer quick peak electricity demands.
Peak demand and particularly quick and short-lived peaks are when demand for electricity soars, causing a problem for electric grid operators. The amount of electricity drawn from national grids varies enormously at different times of day. It usually peaks in the early evening for a couple of hours after homes are occupied from people leaving school and work. But it’s the short duration peaks that cause such concern. Those common spikes turn up after major televised sporting events, during commercial breaks and in the morning hours. It’s ‘the everyone hits the microwave and refrigerator’ and those industrial startups with homemakers staring the clothes dryer moments that pull down the available volts and amps.
Grid operators matching the highs and lows in demand with a steady supply is a major challenge. The companies typically top up a ‘base’ supply of energy with electricity from power plants that are just switched on to cope with the peaks. But those natural gas-fired generators often used to feed these peaks are notoriously inefficient, expensive to run and sit idle for long periods of time. The system as it works now is both energy consumption dense and financially consumes lots of money for very little operating time. Answering peaks is a huge chunk of your power bill.
University of Leeds Professor of Engineering, Yulong Ding, and colleagues are proposing a more environmentally friendly system that could also be much cheaper to run.
Of crucial significance, the system would store excess energy made by a plant supplying the ‘base’ demand and use this to supply the ‘peaks’ in demand – as and when they happen. The clever boffins of the UK and China have a fascinating take on forming a fuel to store energy.
The practice is to use excess electricity to run a unit producing liquid nitrogen and oxygen – or ‘cryogen’ from right out of the atmosphere. At times of peak demand, the nitrogen would be reheated to a boil – using waste heat from the power plant heat and as needed from the environment. Step one: the hot nitrogen gas would then be used to drive a turbine or engine, generating the peak demand’s ‘top up’ electricity.
Step two: the oxygen would be fed to a combustor to mix with the natural gas before it is burned. Burning natural gas in pure oxygen, rather than air, makes the combustion process more efficient and produces almost no nitrogen oxide. Instead, the ‘oxygen + fuel’ combustion method produces a concentrated stream of carbon dioxide that can be removed easily in solid form as dry ice. Clean, neat and the only effluent would be what’re produced when making the cryogen. Smartly managed with adequate storage, the efficiency could be quite high.
Operating an integrated system with cryogen and the down process methods the amount of fuel needed to answer peak demand could be cut by as much as 50%. Greenhouse gas emissions would be lower too, thanks to the greatly reduced nitrogen oxide emissions and the capture of carbon dioxide gas in solid form for sale. The base production efficiency if effluent free would make peak demand effluent free as well. It’s an elegant, innovative and simple design that begs the question how could this not have been thought of before?
Professor Ding said, “This is a much better way of dealing with these peaks in demand for electricity. Greenhouse gas emissions would also be cut considerably because the carbon dioxide generated in the gas-fired turbine would be captured in solid form. On paper, the efficiency savings are considerable. We now need to test the system in practice.”
Technically speaking the new system combines a direct open nitrogen (cryogen) expansion cycle with a natural gas-fuelled closed Brayton cycle and the CO2 produced in the system is captured in the form of dry ice. Thermodynamic analyses were carried out on the system under the baseline conditions of 1 kg s−1 natural gas, a combustor operating pressure of 8 bars and a cryogen topping pressure of 100 bars. The results show that the energy efficiency of the proposed system is as high as 64% under the baseline conditions, whereas the corresponding electricity storage efficiency is about 54%, an 10% gain or nearly a 20% improvement.
A sensitivity analysis has also been carried out on the main operating conditions. The results indicate that the baseline performance can be enhanced by increasing the gas turbine inlet temperature, decreasing the approach temperature of the heat exchange processes, operating the combustor at an optimal pressure of ~7 bars and operating the cryogen topping pressure at ~90 bars. Further enhancement can be achieved by increasing the isentropic efficiency of the gas turbine and the liquefaction process. The results of this work also suggest that the power capacity installation of peak-load units and fuel consumption could be reduced by as much as 50% by using the newly proposed system. Further work is suggested for an economic analysis of the system.
The engineering choices for a working design are a huge list with lots of variables to work through for different situations. The outstanding point is the existing generating capacity could fuel up for the peaks leaving the whole investment for fresh fuel sourced peak demand generation out of the cost equation. It’s a superb idea with lots of potential, not just for power plants either.
Here is the original post: New Energy and Fuel
May 29, 2013 Energy Talks
Global warming is one of the “hottest” issues nowadays. The current climate change is the worst yet to happen. Global warming is an overall increase in world temperature which is attributed to the increasing number of greenhouse gases trapped in the atmosphere. Searching an alternative energy source is considered a way of reducing the toxic emissions.
Greenhouse gases can be produced both by natural and industrial processes. The most abundant greenhouse gases on earth’s atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, ozone and CFCs.
There are several sources of greenhouse gases. Burning of fossil fuels and deforestation lead to higher concentration of carbon dioxide in our atmosphere. Without the trees and plants to take in the carbon dioxide emitted by burning fossil fuels, natural gas and petroleum products, all of the CO2 emitted stays in the atmosphere.
Also the use of CFCs or chlorofluorocarbons in refrigeration systems and in fire suppression systems and other manufacturing processes also increase the greenhouse content of our atmosphere. While the use of non-organic fertilizers in agriculture also lead to higher nitrous oxide concentrations, another greenhouse gas.
In the United States, greenhouse gas emissions mainly come from the use of fossil fuels as energy source. Approximately 82 percent of the greenhouse gas emission in the United States in 2006 came from the combustion of coal, natural gas and petroleum (United States Energy Information Administration). Meanwhile in Asia, Chine is expected to increase its emission of greenhouse gas because of the construction of old-fashioned power plants in its internal provinces. Currently, the carbon dioxide concentrations in the atmosphere are the highest in 150,000 years. The 1990s was most likely the warmest decade in history, while 1998 was the warmest year (Greenpeace).
Not controlling the greenhouse gas being emitted by human activity can increase climate change the next hundred years that will be much faster than anything known and recorded in history. There are necessary steps to be undertaken to control the toxic emission that will soon be killing us.
To minimize the consumption of oil, petroleum and other fossil fuel, we should use energy efficiently. Energy that we use should be generated from renewable energy source, which would mean harnessing the natural energy from the sun, winds, crops, tides and waves.
Green energy is another term used to describe sources of energy that are considered to be environmentally friendly, which is also similar to the renewable sources of energy.
There are numerous ways of generating electricity and energy from renewable and natural sources that generate clean and safe energy. Wind, sun, and heat can generate electricity for less price and less carbon emission than those of coal and even gas.
Shifting the world’s attention to alternative fuel source other than relying on fossil fuel is among the solutions in resolving the drastic climate change. Greenpeace cited that with renewable energy and using it smartly, can deliver half of the world’s energy needs by 2050. Greenpeace also cited that it is feasible to reduce carbon dioxide emission to almost 50 percent within the next 43 years.
Governments are taking steps to use and tap alternative energy sources as main source of energy. The European Union leaders made an agreement in March 2007 to ensure that 20 percent of their nation’s energy should come from renewable fuels by 2020. This is part of their effort to cut carbon dioxide emissions and other greenhouse gas. There are even governments offering incentives to their residents who are using green energy.
Alternative energy source may not be the only way to reduce the greenhouse emission that human activity produce. There are simple ways in which we can do to contribute in reducing toxic gas emission and mitigate global warming.
Have a look at www.greenenergygroups.com
Lucas Price – http://thedownloadshub.com/
May 27, 2013 Energy Talks
The individual market for carbon offsets is growing and San Francisco airport (SFO) has just done their part to make carbon offsets more available to the common traveler with their new Climate Passport kiosks.
First, what are carbon offsets?
Carbon offsets are monetary units that go towards funding projects to make up for the environmental damage done from carbon dioxide and other greenhouse gas emissions. Basically, the purchase of one carbon offset represents the effort to offset the damage caused by one metric ton of carbon dioxide or other greenhouse gas. The money could go to projects such as wind farms, hydroelectric dams, destruction of landfill methane, or reforestation projects.
It has been common for large corporations and governments to buy carbon offsets in efforts to meet the caps from the amount of carbon dioxide they are permitted to emit. However, there is also a smaller individual market for carbon offsets of which SFO is trying to take advantage. SFO is the first airport to provide these carbon offset kiosks where one can voluntarily buy carbon offsets to compensate for the carbon dioxide their part in a flight will emit.
How to purchase a carbon offset at SFO.
To purchase carbon offsets at SFO, you can visit one of three of their Climate Passport kiosk, enter your flight information, and let the kiosk calculate the pounds of carbon dioxide you are responsible for from your particular flight. Then if you decide you want to fund a project to offset the damage done by your flight, you can purchase the amount of carbon offsets a $13.50 per ton needed to cover your portion. For instance, if you have a round-trip from SFO to New York’s JFK, it will cost $23.42 to cover your part, hardly more than cheap SFO airport parking.
Where is your money going?
Carbon offsets purchased at The Climate Passport kiosks at SFO will fund local projects—currently, a reforestation project in Mendocino County and to a bio-diesel fueling project in San Francisco.
Who’s to say what the future holds for the individual market for carbon offsets, but at least SFO is making their kiosks available and convenient for those travelers who would like to do their part to undo the carbon footprint they have create during their travels.
Ryan Frank is a 23 year writer and blogger living in San Diego, CA.