Category Archives: Tech News

New Breakthrough In Lithium-Oxygen Battery Technology

http://www.iflscience.com/chemistry/two-battery-breakthroughs-future-electric-cars

Several obstacles have been overcome in the quest for the perfect transportation battery, one that will carry as much charge for its weight as possible. The announcement comes just a day after another paper revealed a big step forward for the lithium-ion batteries currently favored in electric cars and phones.

Lithium-air batteries represent the holy grail of electric cars. In theory, they are capable of being almost as energy dense as a full tank of gasoline, something other battery types will never approach. While other uses, such as home energy storage, are more focused on cost, the ratio of charge to weight is of vital importance to displacing petrol-powered cars from the roads.

Professor Clare Grey of Cambridge University has announced in Science a series of modifications that bring lithium-air batteries far closer to practicality, although she acknowledged to IFLScience that there are still some big steps left to go.

Theoretically, lithium-air batteries can store 12 kilowatt hours per kilogram (Kwh/kg), compared to 0.18 Kwh/kg for lead-acid batteries and 13 Kwh/kg for petrol. As Grey pointed out at a press conference, the potential of lithium-air comes from the fact that it uses, “two very light elements, lithium and oxygen (mass 7 and 16) that react to form the product lithium peroxide.”

However, existing lithium-air batteries come nowhere near their potential. “The reversible capacity… is determined by the pore volume of the porous electrode,” the paper notes. Existing electrodes not only have pore volumes far below the theoretical maximum, but get clogged easily, preventing lithium and oxygen diffusing through the electrode and creating considerable inefficiency.

Grey’s team used one-atom-thick sheets of graphene to produce a highly porous electrode. This “is the lightest carbon you could possibly use,” Grey told IFLScience, and her team use “The cheapest form of graphene. We also use very little of it.”

A further modification was to replace lithium peroxide (Li2O2) as a proton source with lithium hydroxide (LiOH), reducing chemical damage and eliminating the need to keep batteries dry. This meant performance was maintained even after 2,000 charge-discharge cycles.

The result was a battery with 93.2% energy efficiency. Grey and her colleagues acknowledge commercial versions would likely be lower, but this compares well with efficiencies of around 85% for lead acid batteries, and in the 70s for alternative lithium-air versions, while still some way short of lithium-ion batteries. In keeping with this efficiency, the gap between input and output voltage is just 0.2 Volts.

These advantages don’t mean lithium-air-powered cars will hit the roads any time soon, Grey told IFLScience, “The rate is still very slow, so we need to find ways to increase oxygen solubility and design electrode structures that allow higher rate cycling.” Moreover, while the lab version works well in pure oxygen, Grey says the lithium anode “Reacts with N2 and CO2, both of which are found in air! We need to also reduce CO2 intolerance on the cathode.” Nevertheless, she said, “Given the extremely high energy density, its worth the challenge.”

Grey said at a press conference that before lithium-air batteries are used for cars, they are likely to have smaller applications, such as hearing aids, which would provide opportunities for refinement.

While lithium-air batteries may be the eventual winners in the battery race, the lithium-ion is likely to dominate for a while to come. Besides lacking the theoretical potential of lithium-air, the ion batteries are hamstrung by the cost and short lifespan of graphite anodes.

In Nature Communications, Professor Zhongwei Chen of the University of Waterloo, Canada, announced that silicon anodes allow lithium-ion batteries to store 40-60% more energy at the same size, potentially greatly extending the range of electric cars without adding to the weight. A modification like this is likely able to be brought to market far more quickly than Grey’s work. “As batteries improve, graphite is slowly becoming a performance bottleneck because of the limited amount of energy that it can store,” Chen said in a statement.

Grid Connectivity of Renewable Energy- Issues & Solutions

Grid Connectivity of Renewable Energy- Issues & Solutions

The promotion of renewable sources of energy is a vast area for public policy from many aspects as energy security, employment generation, clean energy, etc. Electricity Act 2003(EA) introduced a statutory mandate to promote renewable sources of Energy. They are:

  1. Promoting co-generation and renewable while making regulations for tariff determination.
  2. Promote   co-generation and renewables by providing suitable measures for connectivity with Grid and sale of electricity to any person. Also a percentage of total consumption electricity shall be from renewable sources by purchase in each area of distribution licensee.
  3. National policy for permitting standalone systems including renewables sources of energy in rural area.

The National Electricity Policy requires that the percentage for purchase of power from Non-conventional sources, known as Renewable Purchase Obligation (RPO) should be increased progressively and that electricity from renewable sources may be given a preferential tariff.

The statutory provisions in the EA 2003 have given a major boost to the promotion of renewables in India. The currently assessed potential of renewable energy in India, except solar is 87000MW.  Central Govt. has launched an ambitious National Solar Mission which seeks to set up about 20,000MW of Grid  connected solar based connectivity by the year 2022 in three phases. At all India level, the share of electricity from renewables is presently about 4.13%.

The promotion of renewables presents challenges for policy makers and regulators since (i) the cost of Generation is much higher than that of long PPA for conventional resources, (ii)building up of transmission system for low PLF power plants in RE , (iii) ensuring Grid stability while injecting large quantum of non-firm power, particularly from wind, (iv) large coordination among the state & central agencies to implement the project. Though the wind has the problem of variability, the generation from solar power plants is also uncertain to some extent. These two sources are going to make a significant contribution in the future.

The challenges for transmission and dispatch of renewables – based electricity are on many accounts.(i)Issue of evolving appropriate technical standards for connectivity and Grid operations , (ii) Finances are scarce with state transmission utilities and the transmission infrastructure for renewables gets less priority due to lower capacity utilization, (iii) Scheduling and real time grid management and (iv) less time is available for the commissioning of transmission infrastructure to evacuate power from the sources  because gestation period of generating station is hardly one to two years, whereas that of transmission system for power evacuation is close to three years.

Action Plan to solve the above issues:

“Must run” priority  to solar and wind based stations as long as Grid security is not threatened. The grid code has introduced  a new concept of Renewable Regulatory charge for socializing the financial impact of deviations within ±30% band.

The transmission charges for solar power plants only the marginal cost of transmission utility. Central commission has completely waived transmission charges & losses for solar power plants setup by the year 2013 for use of interstate transmission system.

Renewable Energy Certificate (REC):

It is a market based instrument. It is intended to overcome the stagnation at the meagre level of RPO in many states. It was formally launched on 18/11/2010. On every one MWh of electricity generated from Renewable sources, generator is entitled to get once RE Certificate from the central registry, National Load Dispatch centre (implementing agency). There are two categories of REC, viz, Solar & Non-Solar.

  1. It will bring market based efficiency in pricing of renewable based electricity with potential reduction of costs.
  2. It will provide another dependable avenue for revenue realization to generators.
  3. It could facilitate large scale deployment of renewable based standalones without government subsidy.

Standalone Systems/Micro Grids:

There are two possible business models , (i) Subsidy driven & (ii) REC driven. Subsidy driven model entails both capital & tariff subsidy. Such subsidy given either as annuity or Generation Based Incentive (GBI) can reduce the electricity cost close to Rs.4~5/unit. The real difficulty in this first business model comes from the expectations of consumers for supply at subsidized rates comparable to typical rural supply by utilities in India ( for example of BPL connections). Hence, the promotion is difficult.

In the second case, REC driven case, presently in India, REC mechanism covers only grid connected generators based on renewables. If this mechanism is extended to standalone/ off Grid systems through some institutional mechanism for verification and metering of generation, Renewable based  Off-Grid/standalone has the potential to become financially viable without any subsidy. Grid connectivity of many small RE generators( eg: 1kW and above) will create lots of grid disturbance issues, which will be difficult to manage at this moment by the Utilities. Hence, based on generation, even for self-consumption, suitable REC shall be issued for 0.25Mwh/0.50Mwh/1Mwh. The same can be marketed even at floor price(nearly Rs 9/- per unit for solar). This will be attractive for the solar generators, even for roof top domestic solar consumers. Hence, return on investment (RoI) can be achieved at an early date and attract more consumers.

It is right time to formulate new strategy and regulations for more solar power (small & large scale) under standalone system/Off Grid under REC mechanism.

 

Solar Energy Savings

The average household today pays nearly $170 each month in home energy costs. Some estimates have energy costs pegged at almost $200 per month, a cost of $2,400 for the entire year.

It’s important to look at the long term picture when evaluating the amount of savings the addition of a solar panel system to one’s home will bring. With energy expenses rising each year of due to rising utility rates it’s easy to see how fast the money saved builds up.
Annual Energy Costs

SolarEnergySavingsAnnualCostsSolar PV systems are warrantied for 25 years, and since 2001 energy costs in the United States have risen an average of 3.75% annually. At a conservative estimate let’s say the rate of increase for energy costs holds steady, an average household today paying $2,400 per year in energy costs will pay close to $6,000 at the end of the systems term. The total cost will amount to approximately $100,000, yikes!

This example assumes a 100% coverage of cost, however if 100% energy cost coverage is not within your budget, there are still massive savings to be had.

Some utility companies use a tiered pricing structure where the consumer is charged more incrementally per kWh, the more energy that’s consumed. If you use enough electricity to pay the higher tiered rates, then in essence you shave off the most expensive part of your energy bill by installing a partial demand solar system.

Case in point, for Southern California, using our Solar Calculator, the approximate cost for a solar panel system, before incentives and rebates, to offset 100% energy cost ($170 / month) the system required would be a 7.8 kW system. By offsetting 50% of your energy consumption, the system required would be half that size, or a 3.9 kW solar energy system.

3.9 kW x $9,000 (average price per 1kW) = $35,100 * before incentives

Offsetting 50% of your energy demand might net 60% or more off your monthly bill due to the tiered pricing structure. Over the system’s lifetime that’s a net savings of at least $60,000. That’s cash in your pocket that is not going to your utility company that can be used elsewhere such as college tuition, retirement, or that Hawaii vacation!

A customized quote tailored to your specific project needs will give you the most accurate information on your expected savings. Use our free solar power directory to locate featured local solar installers and schedule a free on-site quote.

Source: http://www.solarenergy.net/Articles/solar-energy-savings.aspx

 

Dr. APJ Abdul Kalam at TKMCE Golden Jubilee Valedictory address

Oath given to Engineering students at TKMCE Golden Jubilee Valedictory address

1. Engineering and Technology is a life time mission. I will work, work and work and succeed.

2. Wherever I am, a thought will always come to my mind. That is what process or product I can innovate, invent or discover.
3. I will always remember that “Let not my winged days, be spent in vain”.
4. I realize I have to set a great technological goal that will lead me to think high, work and persevere to realize the goal.
5. My greatest friends will be great scientific and technological minds, good teachers and great books.
6. I firmly believe that no problem can defeat me; I will become the captain of the problem, defeat the problem and succeed.
7. I will work and work for removing the problems faced by planet earth in the areas of water, energy, habitat, waste management and environment through the application of science and technology.
8. My National Flag flies in my heart and I will bring glory to my nation.