Do wind installations need one-to-one backup? No.

Posted on September 16, 2009. Filed under: Generation Plants, Wind |

Comments from Jeff Anthony, a RENEW board member, manager of industry relations for the American Wind Energy Association (AWEA), and a former Wisconsin utility manager:

[Backup for wind] is a very complex issue. Here are my attempts at (hopefully) simple explanations for why the following four statements are, in all four cases, not really accurate. From a wind power perspective, the four statements amount to the same thing.

STATEMENT: “they (utility) still have to maintain adequate fossil and nuclear capacity for dealing with times without wind.”

** Not really, no. Utilities need to plan for both capacity and energy — wind power is great at providing energy, but does not provide a lot of capacity. So utilities add wind energy mainly to add an energy resource to their mix, to keep energy costs down, to meet renewable energy requirements, and to lower their levels of harmful air emissions. If load growth occurs at a higher enough level (which it is NOT doing presently), they may need to add capacity, too, which wind projects provide a bit, but if they need larger amounts of capacity they would likely look at natural gas plants in the near term and other forms of generation in the long term.

STATEMENT: “[Necessary backup] is the primary reason why utilities charge one to two cents more for each kilowatt-hour coming from wind farms.”

** This is not the case. Utilities do not charge an extra amount in their rates for each kilowatt-hour of energy coming from wind farms anymore that they charge customers an extra capacity charge to provide a reserve margin (e.g., back-up capacity) for when a coal or nuclear plants trips off line and another unit is available to accommodate the loss of a 500 MW coal or nuclear unit. Utilities have a wide range of resources to provide both capacity and energy, and then need to meet requirements to have reserves of capacity and at the same time adequate amounts of energy to meet their customers needs at all times.

STATEMENT: “Each MW of wind farm capacity needs to be offset by a standby MW of natural gas-fired combustion turbine generator capacity.”

** Again, this is not needed, no. This is a very common misperception, that assumes a utility installing a 100 MW wind plants is relying on that project for 100 MW of capacity. That is not the case — utilities install or buy primarily ENERGY from wind projects — not capacity.

Whatever capacity credit they can take for a wind project is really often a “bonus”. You add wind projects to provide cost-effective, emissions-free, price-assured energy. If you need to add capacity, you’re going to look to some other generating technology in most cases.

STATEMENT: “So, from a utility standpoint, you have to add the cost of both (wind turbine and combustion turbine) together before you compare wind to coal or nuclear capacity.”

** No, this would lead to erroneous conclusions. Would one think that you would take the cost of a two-unit nuclear plant and increase it by 50% because you need to have another unit available if one unit of the nuclear plant trips off line at some point ? Of course not. One needs to view adding wind power in the broadest context of how utilities systems are planned, operated and balanced by their operators.

The correct statement above would be “from a utility standpoint, you need to add a small, incremental amount to the energy costs from a wind project to accommodate the variable nature of the wind energy output to ensure that adequate resources / ancillary services are available from the rest of the utility grid. This incremental cost is typically around $5 per megawatt-hour and adds a relatively small, incremental cost to wind energy when these integration costs are calculated.” [For more info, refer to UWIG: ]


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