Changing winds and storing technologies

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.

Why PV solar is still considered expensive?

Photovoltaic  solar industry has started expanding in recent years in US and Europe and the rest of the world also started following. Still solar energy is considered expensive in many parts of the world for various reasons. In most of these countries, energy is predominantly managed by Governments with age-old technologies and transmission systems. Coal is still the major fuel used for power generation and distribution and their infrastructures are old and inefficient. Transmission losses, power pilfering, subsidized power tariffs and even free power for farmers, are some of the issues that compounds the problems. Energy and water are considered more of social issues rather than business issues. For example in India, frequent power failures are common  and sometimes people do not have power even up to 8 to 12 hours  a day, especially  in country sides. Standby diesel generators are integral part of an industry or business. The heavily subsidized power supply by Government from coal-fired power plants is  underrated. The average power tariff in India is still less than $0.07/kwhr.But the reality is they will be using diesel generated power for equal several hours in a day  and the cost of diesel power varies from  $0.24 up to $0.36/kwhrs, almost in par with solar power. The average power cost will amount to $0.18 to $0.20 /kwhrs.

Any slight increase  in oil price will have a dramatic effect in energy cost in India and their balance of payment situation.Governments are in a precarious situation and they have to make a balancing act between subsidizing the energy cost and winning the elections. They often subsidize the power resulting in heavy revenue losses for Government run electricity boards. Most of the electricity boards in India are in red. People are used to low power tariffs for several decades and any increase in the tariff will make the Government unpopular. Greenhouse effect and global warming are secondary issues. With an average economic growth rate at 7% year after year, their energy requirements have gone up substantially. They may need several hundred thousands of MW power in the next 5 to 10 years. They have opened up energy sector to private only in recent years.

Renewable energy industry is relatively new and there are very few large commercial-scale solar and wind power plants in India. Majority of residents and businesses cannot afford high cost of PV solar installation. Even if they install, there is no ‘power- in tariff’ mechanism by Government where consumers can export surplus energy at a higher tariff to the grid. With current power failures lasting 8-12 hours/day, such mechanisms will have no value. The situation is the same in many Asian countries.

The solar panel costs are high due to lack of local production of silicon wafers, batteries and inverters and most of them are still imported. State electricity boards do not have funds to buy power at higher tariffs. Import duties and taxes on imported components are still high making renewable industries uncompetitive against cheap coal-fired,  subsidized power cost of $0.07/kwhrs .India requires massive investment on renewable energy industries. But most of the power projects which are under planning stage or under implementation are based on either coal or oil or LNG.There is no sign that India will soon become a major player in renewable energy.

In PV solar projects, the cost of storage batteries are higher than the solar panel during the life cycle of 25 years. If the life of a battery is 8 years then you will need 3 batteries during the life cycle. For example, if you use 100 watts solar panel with a life span of 20 years, the initial cost of solar panel may be $300 which will generate an average power of 140 watt.hrs /day. If you plan to store 5 days energy using a battery, you will enquire 5x 140= 700 watt.hrs battery, costing about $175.If you have to replace batteries 3 times during the life span of 20 years then the cost of battery is 3×175= $525.You have to add operation and maintenance cost, in addition to it. Therefore, your investment on batteries is 1.75 times more than solar panels. This cost will substantially add up to your energy cost.

In most of the Asian countries where they cannot export surplus power to the grid, they have to rely only on batteries. This high cost of stored energy is not remunerative because they cannot export this surplus to the grid at a higher tariff. This situation is not likely to change at least in the short-term.