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Linepack ‘Park and Loan’ - Estimated Volume. UNC Transmission Workgroup, 11 February 2011. Estimated release volume. We previously indicated: Decision to release and volume released at discretion of National Grid. Potential range of park and loan between 2 and 10mcm.
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Linepack ‘Park and Loan’ - Estimated Volume UNC Transmission Workgroup, 11 February 2011
Estimated release volume • We previously indicated: • Decision to release and volume released at discretion of National Grid. • Potential range of park and loan between 2 and 10mcm. • After further analysis we now estimate: • Release park and/or loan on 60% to 80% of days. • Most often net volume of release between 2mcmand 6mcm.
Estimated Release Volume (2) • More uncertainty at early release times. • More certainty later in gas day, but limited time for physical rate increase/decrease. • Likely to release both park and loan at same time, depending on operational conditions. • Minority of days with zero release - for example following recent supply loss, and uncertainty over subsequent reliability of this supply.
Uncertainty of physical imbalance • Uncertainty reduces during the gas day. • Current incentive to ensure closing linepack (CLP) is close to opening linepack (OLP), whilst minimising effect on market. Target change = 2.8mcm. • In 2010, achieved average difference of 2.0mcm. • Projected closing linepack (PCLP) is increasingly accurate during gas day, demonstrating increasing certainty of physical imbalance. • Of course late changes can occur. • The following graphs illustrate this.
