Wind Turbines and Water Heaters Load Control For Providing Power System Balancing Services Ken Dragoon Renewable Northwest Project PNDRP July 2010

Load Control for Balancing Services Traditionally, utilities dispatch flexible power generators when demand and supply are out of balance. – Reserve units, especially those on Automatic Generation Control, are used to bring demand and supply closer together. Balancing is expensive. – Opportunity costs to holding reserve on the most flexible generators. – Wear and tear on large rotating equipment experiencing significant stresses and strains when output levels change rapidly.

Wind and Scheduled Wind on BPA

Balancing Reserve Deployment on BPA

Some Loads More Flexible than Generation Electric water heating loads are particularly attractive because no rotating equipment is involved. – Insignificant wear and tear involved in turning on and off electric resistance heating elements. – Response times are theoretically very fast compared to changing the output of large rotating equipment. – Significant loads all year. Other loads also of value. – HVAC – Municipal water pumping loads

Increased Need for Balancing Services Addition of variable output resources such as wind increase need for dispatchable resources/loads. – Increased focus on storage. Insulated hot water tanks and buildings constitute an important source of storage. – Energy can be stored as heat (cold) for useful lengths of time, with relatively low losses.

Load Control: Untapped Storage Electric water heaters in the Northwest alone represent roughly half a billion dollars in existing energy storage infrastructure. – Equivalent to many billions of dollars of competing energy storage technologies (batteries, compressed air, pump storage, etc.) – Storage capability can be accessed by adding communication and control equipment to selectively enable or disable water and space heaters to absorb unexpected changes in load or renewable energy output– fast, no moving parts. – Several commercially available technologies already developed. Thermal Storage Costs Less!

Water Heater Storage Capability Source: Steffes Corporation In the Northwest: – More than 2,000 MWa water heating load – 4,000 MW of coincidental peak demand.

Water Heater Storage Capability In the Northwest: – More than 2,000 MWa water heating load – 4,000 MW of peak demand. Source: Steffes Corporation Equivalent to PEV battery at ~$20,000.

Thermal Storage-- Low Cost Source Source: Sandia National Laboratory

Thermal Storage-- Low Cost Source Source: Sandia National Laboratory Nissan Leaf Battery at $750/kWh, $2,500/kW (below cost)

Thermal Storage-- Low Cost Source Water Heater Thermal Storage Source: Sandia National Laboratory and Steffes Corporation Nissan Leaf Battery at $750/kWh, $2,500/kW (below cost)

Avedøre District Heating Hot Water Storage Units About 12 MW of storage from the CHP plant serving Copenhagen. Nearly 50,000 cubic meters of storage capacity. No electric heating elements… yet. Henrik Bindslev, Risø Director: The Danish power system will move from one where supply responds to demand, to one where demand responds to supply.

Thermal Load Control is the Future In short term, operating procedures such as intra hour trading and balancing area sharing will reduce the balancing burden from wind projects. Storage becomes economic in the longer term. – Existing thermal storage infrastructure is economic now. – Denmark is completely focused on load control to achieve 50% of electric power from wind. Several pilots in the offing to explore further.

Questions