Shouldn't it be called Mare Occidentale? More than a century ago, when astronomers first studied the mare in detail, convention defined the eastern part of the Moon as the side facing east as viewed from Earth. Mare Orientale translates to the “Eastern Sea,” which seems a bit odd since it sits on the Moon’s western edge. This wide view of the waning gibbous Moon shows Mare Orientale in context during the favorable libration of Jan. This would seem to imply that only 50% of its surface is visible, but thanks to librations - the cyclic north-south nodding and east-west rocking of the Moon - the actual amount is 59%. It turns at the same rate that it revolves, with one side facing Earth. We only see the lunar nearside because the Moon’s rotation period is exactly synchronized with its period of revolution. This little-sailed sea only comes into its own when a favorable libration periodically swivels it into view. Despite being 930 kilometers (580 miles) across, the mare straddles the Moon's southwestern limb, where foreshortening often “compresses” it out of sight. If you’ve never observed the Mare Orientale bull's-eye, the Moon's youngest and best-preserved impact basin, don't kick yourself. Color-coding for gravity reveals where mass is concentrated (red) and where there’s a deficit (blue).Įrnest Wright / NASA-GSFC Scientific Visualization Studio Project typically supports claims of additionality.Spanning 930 kilometers or about the distance between New York City and Charlotte, North Carolina, the Moon’s Mare Orientale exhibits three distinct, mountainous rings surrounding a central, magma-flooded basin.Buyer agrees to pay fixed price through supplier or directly to seller.Project must be in same load zone as buyer.Buyer receives and takes title to physical energy.If the market price is lower than the VPPA price, the buyer must make up the difference. Additionality is a complicated concept, but implies the buyer’s investment is credited with creating new, clean sources of energy, an important distinction on sustainability reports and within the ESG community. Physical PPAs can also support claims of additionality.Ī VPPA establishes a fixed price for the electricity produced by the project, typically called the “strike price.” If the wholesale market price, i.e., the price the local grid pays the project developer for the power, exceeds the strike price, the VPPA buyer is paid the difference. Second, a VPPA can often support claims of additionality. The buyer owns those RECs, which it retires to reduce its scope 2 emissions. First, a renewable energy VPPA produces RECs. So, what’s in it for the buyer? A few things. Instead, the electricity produced from the project flows directly into its local grid. No electricity flows to the buyer from the renewable energy project, whether the project is a solar power array or windfarm. Along with the green power delivered, the energy buyer in a renewable energy PPA receives renewable energy certificates (RECs) for each MWh of energy produced.Ī virtual power purchase agreement is a purely financial instrument. For instance, a PPA contract enables them to run at least part of their operations on green power at a fixed, set price, which is great both for the environment and hedge against long-term power prices. The PPA is a contract that schedules the delivery of electricity to the buyer directly from the renewable project and sets its price.Ĭompanies and organizations enter into renewable energy PPAs for different reasons. (Note that in this article we are specifically concerned with renewable energy projects). So what’s the difference between a physical PPA and a virtual PPA?Ī physical power purchase agreement is a contract that a typically large energy buyer enters into with a project developer. One way large commercial, industrial, and institutional energy buyers can quickly and effectively green their portfolios, reduce their carbon footprints, and move towards net-zero carbon emissions is by entering into either a physical power purchase agreement (PPA) or virtual power purchase agreement (VPPA) for clean energy.
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