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Battery 8hrs and Hydrogen 2 months autonomy24hrs batery storage modelBattery 10hrs and Hydrogen 17hrs autonomyBattery 8hrs and Hydrogen 2 months autonomy172 hrs (one week) battery autonomyAfrica- Australia conference

Most of the renewable energy projects that are now set up around the world are grid connected with feed-in power tariff arrangement. People can generate their own electricity by solar/wind to meet their demand and supply the surplus power to the grid at an agreed power rates. They can also draw power from the grid if there is any short fall in their production of renewable energy. It is two-way traffic. There is an opportunity for people to generate revenue by sale of surplus power. It is an incentive for people to invest on renewable energy and that is why the investment on renewable energy has steadily increased over a time. But this is not the case with many developing and under developed countries. The situation is still worse in many islands where there is no centralized power generation at all or power distribution through grids. They depend on diesel generators. Even to transport diesel from mainland they have to use diesel operated boats. They have no drinking water even though they are surrounded by sea. I happened to visit a remote island in PNG few years ago and saw the plight of those people first hand. They live in absolute poverty and nobody cares to offer them a solution. Their voices are never heard and permanently drowned in the deafening roar of the sea.

The problems of supplying clean power and water to these remote islands are not only political but also technical and commercial in nature. One has to use only commercially available systems and components which are meant for a single or three-phase grid connected power supplies. Even though renewable energy sources basically generate only direct current (DC), one has to convert them into alternate current (AC) for easy distribution and to use appliances which are designed for AC operations. Isolated communities like islands can use direct current and also use DC operated appliances because they are commercially available and they are more efficient. Anyhow most of the house appliances need DC supply and AC/DC converters are commonly used for this purpose thus sacrificing efficiency in the process. They also need better storage solutions because they are not connected to the grid and they have to necessarily store power for several days. Some of these islands are connected with inefficient wind turbines backed by diesel generators. It is an absolute necessity to incorporate a long-term storage capabilities in the system if one has to offer a continuous power and clean water. If the wind velocity is not enough (during off seasons) or if there is no sun (cloudy) for days together and if there is not enough storage capacity, then all the investment made on the project will be of no use. Any half-baked solutions will not serve the real purpose.

There are also commercial problems because a well designed system will cost more, which will eventually increase the power tariff. Unless the Government subsidizes the power   sufficiently, people cannot afford to pay for their electricity or water. It requires a careful planning and community consultations to set up a ‘stand alone renewable energy projects in islands’. Governments in the pacific islands should act with great urgency because there is also a risk of inundation by sea level rising due to global warming.

We are in the process of designing a solution to provide such islands with clean power, clean drinking water and even wireless connectivity for schools so that children can get education. It may sound ambitious but it is the first step one has to take into long journey of sustainability and self-reliance by these isolated communities. There is a good possibility that such island may one day become completely independent and self-sufficient with clean power and water.

The same solution can be implemented in other countries too. Many countries have necessary infrastructure to generate and distribute power yet they suffer regular power cuts and black outs due to inefficiencies in their system.

Our proposed solution can provide uninterrupted clean power and water because the system will have long duration centralized energy storage. We have made a detailed analysis of various alternatives available for the above purpose using Homer hybrid solution software. The solution proposes a PV solar with storage solutions using battery bank as well as Fuel cell back up. The solution also proposes a long duration of storage ranging from few hours up to a fortnight .It is a standalone system with complete energy management and suitable for remote operations. The solution can also incorporate wind turbine in addition to PV solar depending upon the site and wind velocity profile.

The model is to supply clean power and drinking water for 600 families with an average 3 people in a family. The system will supply power at the rate of 1.50kwhrs/day/person (1800 x1.5 = 2700kwhrs/day) and drinking water at the rate of 200 lits/day/person (1800 x 200 lit/person= 360,000 lits/day).The power for a desalination plant will be 1980 kwhrs/day. The system is designed for a total power generation capacity of 4680Khwhrs/day.

The model is based on battery storage as well as based on Hydrogen storage with varying durations. Comparative analysis is shown in the figures.

The first window is based on PV solar with  2 months Hydrogen autonomy.

The third window is based on PV solar with battery storage 5 days and Hydrogen 17hrs autonomy.

The fourth and fifth window is based on PV solar with battery 12hrs and Hydrogen 17hrs storage autonomy with varying panel costs

The sixth window is based on PV solar with 172 hrs (one week) battery autonomy.

The resulting analysis indicates that a centralized Hydrogen storage with Fuel cell back up offers the most economical solution even though the power tariff is higher than a system with battery storage. The investment for long duration battery storage is almost double that of Hydrogen based solution. The cost can further be reduced if and when the Electrolyzers as well as Fuel cells are manufactured on mass scale. The added advantage with this system is it can also provide Hydrogen fuel for Fuel cell cars and boats substituting diesel. One day it may become a reality that these isolated islands can become completely self sufficient in terms of water, fuel and power with no greenhouse gas emissions. This solution can be replicated to all the islands all over the world.

Note:

The above system can also be installed in many developing countries in Africa which is an emerging market. An Africa-Australia Infrastructure Conference  will be held in Melbourne, Australia on 2-3 September  2013 and it will offer a platform for Australian companies to invest in Africa on infrastructural projects.

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Wind energy is one of the fastest growing renewable energy sources in the world and in 2011 the global market grew by 6% with 40.5 GW new powers brought online, according to Global Wind Report. However storage of intermittent renewable energy is a critical contributing factor in renewable energy development. A study was conducted by University of California for California Energy Commission on the economic and environmental impact of for energy storage technologies and the ways to improve the energy efficiency of wind energy. When there is a strong wind there is no demand for power, and when there is a high demand for power there is no wind. This anomalous supply demand gap demands a reliable way of storing wind power during high wind velocity periods.

They examined for energy storage technologies namely 1.lead acid batteries, 2. Zinc Bromine flow batteries, 3.Hydrogen electrolyzer and Fuel cell storage system and 4.Hydrogen option to fuel Hydrogen cars with Hydrogen. By using NREL (national Renewable Energy laboratory) computer simulation model HOMER  for high wind penetration of 18% in California, they concluded that Hydrogen storage is the most cost-effective than other battery storage technologies and using Hydrogen to fuel Hydrogen cars is economically attractive  than converting Hydrogen into Electricity. The environmental impact of using Hydrogen is benign compared to batteries with their emissions.

“The key findings of this experiments are as follows: Energy storage systems deployed in the context of greater wind power development were not particularly well used (based on the availability of “excess” off-peak electricity from wind power), especially in the 2010 time frame (which assumed 10% wind penetration statewide), but were better utilized–up to 1,600 hours of operation per year in some cases–with the greater (20%) wind penetration levels assumed for 2020.

The levelized costs of electricity from these energy storage systems ranged from a low of $0.41 per kWh—or near the marginal cost of generation during peak demand times—to many dollars per kWh (in cases where the storage was not well utilized). This suggests that in order for these systems to be economically attractive, it may be necessary to optimize their output to coincide with peak demand periods, and to identify additional, value streams from their use (e.g., transmission and distribution system optimization, provision of power quality and grid ancillary services, etc.).

At low levels of wind penetration (1%–2%), the electrolyzer/fuel cell system was either inoperable or uneconomical (i.e., either no electricity was supplied by the energy storage system or the electricity provided carried a high cost per MWh).

In the 2010 scenarios, the flow battery system delivered the lowest cost per energy stored and delivered.  At higher levels of wind penetration, the hydrogen storage systems became more economical such that with the wind penetration levels in 2020 (18% from Southern California), the hydrogen systems delivered the least costly energy storage.

Projected decreases in capital costs and maintenance requirements along with a more durable fuel cell allowed the electrolyzer/fuel cell to gain a significant cost advantage over the battery systems in 2020.

Sizing the electrolyzer/fuel cell system to match the flow battery system’s relatively high instantaneous power output was found to increase the competitiveness of this system in low energy storage scenarios (2010 and Northern California in 2020), but in scenarios with higher levels of energy storage (Southern California in 2020), the electrolyzer/fuel cell system sized to match the flow battery output became less competitive.

The hydrogen production case was more economical than the electrolyzer/fuel cell case with the same amount of electricity consumed (i.e., hydrogen production delivered greater revenue from hydrogen sales than the electrolyzer/fuel cell avoided the cost of electricity, once the process efficiencies are considered).

Furthermore, the hydrogen production system with a higher-capacity power converter and electrolyzer (sized to match the flow battery converter) was more cost-effective than the lower-capacity system that was sized to match the output of the solid-state battery. This is due to economies of scale found to produce lower-cost hydrogen in all cases.

In general, the energy storage systems themselves are fairly benign from an environmental perspective, with the exception of emissions from the manufacture of certain components (such as nickel, lead, cadmium, and vanadium for batteries). This is particularly true outside of the U.S., where battery plant emissions are less tightly controlled and potential contamination from improper disposal of these and other materials is more likely. The overall value proposition for energy storage systems used in conjunction with intermittent renewable energy systems depends on diverse factors:

The interaction of generation and storage system characteristics and grid and energy resource conditions at a particular site The potential use of energy storage for multiple purposes in addition to improving the dependability of intermittent renewable (e.g., peak/off-peak power price arbitrage, helping to optimize the transmission and distribution infrastructure, load-leveling the grid in general, helping to mitigate power quality issues, etc.)

The degree of future progress in improving forecasting techniques and reducing prediction errors for intermittent.  Electricity market design and rules for compensating renewable energy systems for their output”. Hydrogen storage and Hydrogen cars hold the key for future renewable energy industries and Governments and industries should focus on these two key segments.

Photovoltaic  solar energy  is becoming popular as a source of clean energy and an alternative to fossil fuels to combat climate change. Though the initial cost is expensive people have started realizing the potential of PV solar as  a real alternative to grid power, especially when they can export surplus power to the grid and earn some revenue. It is  a source of income for potential investors as the energy cost keeps rising steadily. The cost of solar panels, batteries and inverters are slowly coming down as the systems get more popular and more competition is created in the market. However, during cloudy days or when the solar hours are less, the power generation by solar panels is considerably low. Moreover, the ‘power in tariff ‘ system is not available in many countries especially in developing countries. Therefore, energy storage becomes an issue. Lead acid batteries serve as storage devices for smaller applications but it becomes expensive for lager systems. Operation and maintenance, replacement and waste disposal are some of the issues with battery storage.

Generating Hydrogen on site using solar power and storing Hydrogen under pressure in a tank is the best method of storing solar energy. The stored Hydrogen can be used to generate power using a Fuel cell as and when we need power. However, the amount of energy required to convert water into Hydrogen using Alkaline Electrolyzer or Solid Polymer Electrolyzer is still high, averaging 5-7 kwhrs/m3.When you calculate the economics of  Hydrogen storage versus battery storage using a computer modeling for a stand alone system, it is clear that Hydrogen storage is more economical and also guarantees an uninterrupted power supply using a Fuel cell.

One US company has developed a Carbon doped Titanium oxide nanopowder visible light photo catalyst to  generates Hydrogen using sun’s light energy. The company claims that it consumes only one-third of the power consumed by PEM Electrolyzer or half of an Alkaline Electrolyzer.It can be easily installed at roof tops and it can generate Hydrogen even at one-third of sunlight because it can effectively use short UV light and blue wave length of suns light because these energetic wavelengths penetrate cloud cover more effectively than the rest of sunlight. A 2mm modular solar panel can be installed on roof top or installed in multi-acre field installations. Even during the absence of sunlight the company claims it can use grid power to generate Hydrogen using its hybrid integral (MMO) Mixed metal oxide Titanium anode as efficiently as PEM Electrolyzer.

While a PEM electrolyzer generates about 1.3kg Hydrogen from a power input of 100Kwhrs, this model can generate about 2.5kg Hydrogen using MMO + TiO2 anode and about 3.8kg using TiO2 alone. (Based on higher heating value of Hydrogen at 39.4 kwhrs/kg).The panel consuming 26.7kwhr power at 1.0Volt DC current at Anode can generate 1.25kg Hydrogen with Electrolysis electrical efficiency at 148%.  This will make Hydrogen fuel a commercial reality because it will consume only 21.36 kwhrs of Dc power to generate 1 Kg Hydrogen. The generated Hydrogen can generate about 15 Kw power using a Fuel cell. This is an elegant solution to generate and store power using sun’s light than Photovoltaic power.

 Photovoltaic (PV) power is becoming popular worldwide as an alternative to grid power for various reasons. It gives an energy independence and freedom, it helps reduce greenhouse gas emission and combat global warming, it helps people taking advantage of various Government subsidies and incentives, and it also generates some revenue by selling surplus power back to the grid. At the end of the period you own the system and claim depreciation and some tax benefits. All these compelling factors may motivate people to opt for PV solar power. But you should also do some math and make a cost benefit analysis to choose a right system for you.

When there is a good sunshine day after day and throughout the year, PV solar is good proposition and can be really rewarding. Unfortunately that is not the reality. There may be many cloudy, rainy and fogging days in a year and your PV solar capacity may be overestimated or underestimated. You know the real data only after one or two years of life experience. It is a long-term financial and ethical decision one has to make and the decision should be absolutely right. You can make such a decision by carefully examining all the factors, not just by looking at the first cost but looking at operating and maintenance costs and all the costs and benefits associated with them.

Storage batteries are inevitable in PV solar systems, especially for grid independent systems. Even with grid connected PV solar system the design and installation of a correct battery bank, controllers and rectifier are important issues. In this article we will discuss about grid independent system because many developing countries in Africa and Asia do not have 24×7 uninterrupted grid power supplies. Many people living in islands have to manage their own power by using diesel generators. This is the stark reality.

Let us assume that you design a system assuming a daily average power consumption of 25,000 kwhrs/day, which is suitable even for a medium size family in US. We made an optimum design study between two  systems; first  containing PV solar,battery,controller for grid independent power supply; and second  system with PV solar, battery, water Electrolyzer,Hydrogen storage  and PEM Fuel cell and a rectifier for grid independent system,  based on the same power consumption of 25,000kwhrs/day. You can clearly see the difference between the two systems by the following data.This financial analysis was made assuming there is no Government subsidies and incentives.

Grid independent system with battery storage for 25,000kwhrs/day power:

Total NPV (net present value):$ 342,926

Levelized cost of energy: $2.94/kwhrs

Operating cost/yr: $22,764

Grid independent system with Hydrogen storage for 25,000kwhrs/day power:

Total NPV (net present value): $ 169,325

Levelized cost of energy : $ 1.452/kwhrs

Operating cost/yr: 8,330

The number of batteries required in the first case is 17 numbers. In the second case, number of batteries required is only 2.Obviously,  the levelized cost of power using  PV Hydrogen (storage) is less than 50% of the power generated using PV battery (storage) for the same energy consumption of 25,000kwhrs/day. The operating cost is only one-third for PV Hydrogen system compared to battery system. Batteries are indispensable in any renewable energy system but reducing their  numbers to the lowest level is important, when the life of the system varies from 25 years to 40 years. The numbers and the cost of batteries and their maintenance cost  will make all the difference.

 

Renewable energy industry has slowly but steadily started expanding in many parts of the world in spite of  high cost of investment and high  cost of energy. Countries like US, Germany and China are now investing on large-scale solar and wind technologies, opening new avenues for investments and employment opportunities. Many of these technologies will undergo several changes over a time before it can completely substitute fossil fuels. How long this process will take will depend upon number of factors; but the single biggest driving force will be ‘the issue global warming and its consequences” and also on uncertainties over oil reserves in the world. Nothing dramatic will happen in the near future except that the concept of alternative source of energy will expand rapidly. It is also an opportunity to discover new forms of fuels, power generation and distribution methods.

The concept of solar energy is now well-recognized as an alternative source of energy because, it is abundantly available, it is clean, generates no pollution and it is silent. The major raw materials such as Silica  and Gallium Arsenide  are  also available but some of the rare earth materials used in PV industries and batteries  are available only in certain parts of the world.  China is endowed with many such rare earth resources. For example, Lithium has limited resources and now bulk of it is produced from natural brines similar to the one at Atacama deserts in South America. It is also available in the form of minerals and ores which many countries are now trying to exploit commercially.

The storage of energy from  solar and wind is  done using deep cycle batteries, most of which are Lead-acid batteries. Bulk of the used Lead acid batteries are recycled but the demand for such batteries keeps increasing. As I mentioned in my previous articles, the sheer weight of these batteries, space required to install them, capacity use, capacity constraints, regular need for  maintenance and life cycle are some of the issues that are critical for renewable industries. In deep cycle batteries, discharging stored energy below certain levels dramatically reduces the life span. Hot climate conditions have certain impacts on maintaining such batteries.Life of a battery is critical because when you calculate the cost of energy over the life cycle of 25 years,the several replacements of battaries and their cost will have a dramatic effect on the cost of energy.

Batteries are indispensable tools in energy industries but their usage can be minimized  to a great extent by using Hydrogen as a storage medium. Let us analyze a simple example of a PV solar system for power generation. We made a computer simulation on three  different  scenario for a PV solar system for a small residence with power consumption at 15,500kwhrs/day. First simulation was based on PV solar, direct grid connect, without  storage batteries but connected directly to the grid, assuming the grid power tariff  is at $0.10/kwhrs and sale to grid tariff at $ 0.30/kwhrs.The second simulation was based on grid independent system  using battery  storage for 8 hrs autonomy. The third simulation is also grid independent, but solar power is connected to an Electrolyzer to generate Hydrogen and store it in a tank. We used a small capacity battery, less than twenty percent  of the capacity used in the earlier case and a Hydrogen storage with Fuel cell along with an inverter. The stored Hydrogen was used to generate power to meet the requirement of the residence, instead of supplying power directly from the battery. The cost of energy using direct grid connect was the lowest $$0.33/kwhrs, while Grid independent with battery storage ,the cost of power was $1,20/kwhrs.In third  scenario with Hydrogen and Fuel cell the cost of power was $ 1.90/kwhrs, but there was surplus Hydrogen in the storage tank. With Hydrogen as a storage medium, the cost of power is high due to initial investment but it is maintenance free and ideal for remote locations.

The Hydrogen and Fuel cell solution though expensive, has a several advantages. The power generated by PV solar is stored in the form of Hydrogen instead of storing in batteries. A single battery is used to keep up a steady current to Electrolyzer but bulk of the energy is stored in the form of Hydrogen. Another advantage with this system is that stored Hydrogen can also be used as a fuel for residential heating as well as to fuel your car.

Renewable energy is one of the fastest growing energy sources of our times. But still there are many obstacles to overcome, before it can substitute current methods of electricity generation using fossil fuels, or substitute petrol in cars. The main obstacle is, the intermittent and unpredictable nature of renewable energy sources, such as wind and solar. Wind blows only certain seasons of the year and then wind velocity fluctuates widely in a day. Similarly sun shines only certain hours in a day and the intensity of radiation varies widely in a day. The wind velocity and sun’s radiation intensity are critical components in designing a reliable energy system. It is an anomalous situation, when we need power, there is no sun or wind; when sun shines or wind blows, we may not need any power. How to overcome this anomaly? That is the key, in successfully deploying renewable energy technologies.

Currently we are using batteries to store the energy. When there is a wind with reasonable velocity or sunshine with reasonable radiation intensity, we can generate power and store them in batteries. The wind velocity should be above certain threshold limit, say such as, a least wind velocity of 3mts/sec for amount of hours, while designing a wind based energy system. The same principle applies to solar energy and we need certain minimum solar   intensity and several hours. But in reality, we don’t get these minimum operating parameters, which make the design of a renewable system more complicated.

Batteries can accumulate these small energy generations by intermittent sources of wind and sun, and store them. But these batteries have certain life between 3-5 years and requires regular maintenance, replacements.They also have certain charging and discharging cycles and limitations. At the end of its life, it has to be disposed carefully because these batteries are made of lead and acid, which are toxic materials. Many companies are trying to introduce better technologies such as ‘flow batteries’. But experience shows that such batteries are confined to only smaller capacities. Large scale storage is expensive and sometimes it is not economically feasible. Lithium-ion batteries are more efficient than Lead-acid batteries, but they are more expensive so the renewable energy projects become expensive and cannot compete with conventional fossil fuels, in spite of higher tariffs offered by Government as incentives. Moreover the demand for Lithium-ion batteries will increase substantially in the future, as more and more Electric cars are produced. But lithium sources are limited and it is not sustainable.

The best option to develop renewable energy systems is to generate Hydrogen using renewable energy and store them, instead of storing them in batteries. We can use stored Hydrogen to generate power, or use as fuel for the car, as and when we need. There are no maintenance or disposal problems with Hydrogen storage, when comparing with batteries. Hydrogen generators (electrolyzers) can generate Hydrogen when the intermittent power flows from wind or sun. They can run from a range of capacities from 5 to 100% of rated capacity and they are more suitable for renewable energy sources. But there will be a loss of energy, because the amount of power required to generate Hydrogen, is more than the power generated from the resulting Hydrogen by a Fuelcell.The initial cost will be higher, but it will give operational flexibility with least maintenance, and even adoptable to remote sites. Technology is improving to cut the cost of fuel cells and electrolyzers so that Hydrogen based renewable energy will become a sustainable source of energy in the future. Hydrogen is the only solution that can solve both power generation and transportation problems the world is currently facing.

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