California boasts world’s largest solar irrigation system

Technological innovation in irrigation is cutting costs, improving reliability and providing solutions to environmental concerns and legislation, reports Dr Anand Rangarajan, executive vice-president of WorldWater & Power Corporation.

On 10 December 2004, the world’s largest solar pumping system was inaugurated at the Seley Ranch in Borrego Springs, California, USA. It irrigates a citrus orchard utilizing a 200HP irrigation pump. The pump setting is 335m deep and delivers about 76L/s of water.

The second largest solar pumping system (50HP) was commissioned in December 2002 at Locke Farm in Firebaugh, California.

These solar pumps provide water without any emissions, save farmers money on electric bills and provide improved power reliability even if there is a blackout, a frequent reality during summer months in many parts of California.

According to a recent report by the Pacific Institute and the Natural Resources Defense Council (NRDC) titled Energy Down the Drain, 90% of electricity used on Californian farms is for groundwater pumping. In 1995, agriculture used about 80% of the developed water supply and consumed 42,000m3, with 4.4 billion kWh of energy embedded in moving this water.

The report concludes that despite a few recent efforts, water planning at the federal, state and local levels has largely failed to consider energy implications.

The San Joaquin valley in California is the largest producer of agricultural goods in the world. It also ranks as the second worst air quality district in the country, after Los Angeles.

Tens of thousands of diesel pumps power irrigation in the Valley. These pumps are the single largest emitter of particulate emissions which are thought to cause asthma in children.

The water agencies in California face similar issues related high costs of moving and treating water. According to the Association of California Water Agencies, water pumping and treatment constitute the largest single use of electricity in California, 7% of total electricity.

This report further predicts that the stakes are rising for water agencies as the state’s electricity utilities grapple with a situation where supply cannot keep pace with demand. Given that thousands of MWs of existing generation hardware is scheduled to be retired due to inefficiency and air pollution concerns, it is clear that cutting and shifting demand is the only option.

In this context, it is clear that moving water, water availability, rising cost and its direct impact on the environment are inexorably linked. It is also clear that new and innovative approaches are needed to solve these critical, interconnected problems.

Large-scale, commercially available solar pumping technology offers new solutions for sustainable re-powering of the water agencies and for changing the face of agriculture in California.

Until WorldWater & Power introduced its technology in 2002, solar pumps were limited to 5HP capacities, mostly using DC motors. Solar panels produce DC electricity from sunlight and the power produced depends on sunlight and temperature conditions. However, the new technology can power standard AC motors up to 600HP for running pumps, compressors, chillers, blowers and so on.

There are two key innovations that form the basis of this new technology, modified Variable Frequency Drives (VFD’s) and a patented switching technology.

Modified VFDs

By making changes to the software and hardware, standard industrial Variable Frequency Drives (VFD’s) could be modified so that DC power could be inputted in addition to the AC power which is normally the input into the VFD.

This modification makes it possible to seamlessly blend AC grid power and solar power, which is a constantly changing DC power and provide a variable frequency AC signal to the motor. The operation of the motor using the VFD also brings additional benefits in eliminating the surge power needed to start large motors. This reduces the peak electricity demand, thereby reducing the demand side of the bill.

The VFD also improves the motor power factor, increasing the electrical efficiency of the motor. With this patented technology, the motor can be operated by solar power alone or in conjunction with any other power source such as grid power and/or power from back-up generators.

New switching technology

A patented switching technology can sense loss of grid power and transfer all of the solar power directly over to the pump within a fraction of a second. This means the system can continue to operate directly with solar power, without interruption.

Under normal circumstances, the solar system will be exporting ‘selling’ power to the electric utility and the pump will operate with blended power.

Exporting electric power to the electric company is called ‘net metering.’ The law requires electric companies to give credit to the power exported at their selling price at that time of day. This law is now enacted in 35 states in the US, including California.

The interconnection rules require that in the event of grid failure, the solar system should automatically disconnect itself from the grid, so that a line man working on the electrical lines is not harmed by power exported into the grid by the solar system. This switching technology is unique in that it complies with this requirement, while at the same time transferring the solar power directly to the motor/pump, without exporting power to the grid. This technology is a world first.

Incentives for farmers

Several states in the US now offer attractive incentives to farmers, industry and commerce and public agencies for investment in solar systems:

· The electric utilities and the
Public Utility Commissions
offer rebates of up to 50% in
California and up to 60% in
New Jersey. These rebates come
from a pool of funds collected
over the years by the electric
companies through a surcharge
called the Societal Benefits
Charge, specifically targeted to
promote investment in green
power technologies.

· California offers a 7.5% state
tax credit.

· About 19 states in the US now
have Renewable Energy
Portfolio Standards (RPS), that
have set targets for achieving a
certain percentage of the elec-
tricity sold in that state to come
from renewable energy sources.
Some states, such as New
Jersey and others, have manda-
tory compliance requirements,
under penalty of fines for non-
compliance. This RPS require-
ment has created a bundled
emissions trading (Green Tags)
market. The sale of Green Tags
provides for a significant
revenue stream to the owner
of the system.

The federal government offers a 10% investment tax credit and accelerated tax depreciation benefits.

Green investment

There is now significant interest from financial institutions, leasing companies and project developers to make direct investments to finance the projects. Although the level of this private investment is not yet at the level of financing available wind projects, it is rapidly growing.

These financing mechanisms make it possible for an entity to acquire a solar system without having to come up with upfront capital. The entity is also able to pay for the system out of the savings on the electricity bill.

There is a convergence of concerns from entities that use and move water:

· high costs and the escalation
and volatility of these costs

· lack of reliable electric power

· air quality and pollution

· potential long term disruption
of power due to security

Simultaneously, there is an emergence of technology, regulatory framework, financial incentives and availability of financing. This combination brings the dawn of a new day and the possibility of sustainable living and development in the USA.

Contact: WorldWater & Power Corporation

Tel: + 1 609 818 0700

Email: [email protected]

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