SCIENCE · INVESTIGATE AND EXPLAIN

Compare lifecycle burdens at matched service

Track fixed and operating contributions without hiding boundaries.

Learning outcome: Calculate a ranking reversal and identify unmeasured environmental indicators.

Starting recap

A/B factors are original teaching assumptions; no factors are attached to dispatch timing packets.

All lessons are open directly. Your saved experiments remain when you leave and return.

Try

At 100 delivered kWh A totals 60 and B 90 kg CO2e; at 1000 A totals 420 and B 180.

Open the experiment

Predict

Does a lower operating factor always imply a lower lifetime total?

Your prediction and reason

Experiment

Calculate 100, 200 and 1000 kWh cases, state the functional unit and audit included lifecycle stages.

Match generation timing, storage and electrical service

Original four-hour electrical service scenario · separate lifecycle evidence · Original four-hour scenario: four one-hour bins each request 4 kW. All generation packets offer 16 kWh; initial storage is zero. Local supply, surplus charging, deficit discharge and at most 1 kW grid support follow a fixed greedy rule. Curtailed potential is not generated bus input. No forecast, emissions, prices, degradation or reliability certification is calculated.

Available local generation timing: Middle-period availability Storage capacity, power and efficiency profile: Ideal fast storage

Reset keeps your prediction, captures and practice history.

Same requested service, different timing and limits

Middle-period availability; Ideal fast storage. Every case requests 4 kW for four one-hour bins: 16 kWh over a four-hour window, not a whole day. Available local generation also totals 16 kWh. Initial storage is zero. Predict whether equal totals are sufficient before comparing the timing and storage controls.

Storage capacity is 4 kWh internal energy. Charge input power is limited to 4 kW; useful discharge output is limited to 4 kW. Charge efficiency is 100% and discharge efficiency is 100%. These are supplied reference profiles, not measured device ratings.

Grid import follows storage discharge and cannot exceed 1 kW. There is no grid charging or grid export. Surplus and deficit cannot coexist in a bin, so charging and discharge never occur together. This stipulated greedy rule is not scheduling optimization. Curtailed potential is unused availability, not generated energy dissipated inside the bus.

Close two distinct accounts

Physical account (kWh): 12 used local generation + 1 grid + 0 initial store = 13 served + 0 charge loss + 0 discharge loss + 0 final store. Residual: 0.

Availability allocation (kWh): 16 available generation + 1 grid + 0 initial store = 13 served + 4 curtailed potential + 0 conversion losses + 0 final store. Residual: 0. This second account allocates potential generation; it does not imply all availability entered the physical bus.

Served 13 + unserved 3 = 16 kWh requested. Do not add unserved demand to either energy balance, or count battery output a second time as a new primary source.

Each bin lasts 1 h. Energy columns are kWh; the first two numerical columns are kW.
Bin	Demand kW	Available kW	Demand kWh	Available kWh	Direct	Charge input	Used generation	Curtailed potential	Storage output	Grid	Served	Unserved
1	4	0	4	0	0	0	0	0	0	1	1	3
2	4	8	4	8	4	4	8	0	0	0	4	0
3	4	8	4	8	4	0	4	4	0	0	4	0
4	4	0	4	0	0	0	0	0	4	0	4	0

Internal storage and energy accounts, all in kWh; start + stored charge − internal withdrawal = end.
Bin	Start store	Stored charge	Internal withdrawal	End store
1	0	0	0	0
2	0	4	0	4
3	4	0	0	4
4	4	0	4	0

Reserve and service are different indicators

The illustrative end-reserve target is 1 kWh internal energy. Final store: 0 kWh; reserve shortfall: 1 kWh; target not met. This comparison did not constrain dispatch and does not guarantee future service. It is not another course requirement. Stored internal energy is not identical to deliverable energy for the lossy profile.

The 75% discharge case assigns all modeled loss to discharge for clarity: 4 kWh withdrawn delivers 3 kWh and loses 1 kWh to conversion. It is not a measured battery rating. No self-discharge, aging, thermal constraints, within-bin fluctuations, costs or emissions are calculated.

Check timing, capacity and an unfamiliar duration

Middle-period availability with ideal fast storage ends each bin at [0,4,4,0] kWh. The first bin still has 3 kWh unmet demand: later generation cannot serve an earlier request. With ideal slow storage the stores are [0,1,2,1]; 5 kWh remains unserved across the window despite meeting the final reserve target.

For a separate paper case, an ideal full 4 kWh store limited to 1 kW output can deliver at most 0.5 kWh in half an hour. Multiply power by duration; the numerical equality of kW and kWh in the live one-hour bins is a convenience, not a unit identity.

Served 13 of 16 kWh requested; unserved 3 kWh; final internal store 0 kWh.

Physical account: 12 used local generation + 1 grid = 13 served + 0 losses + 0 final store (kWh). Curtailed available potential 4 kWh is separate. Illustrative reserve shortfall 1 kWh; this does not establish future service.

Observation to attach to a capture

Captures preserve recipes and replay their calculated results. They are synthetic model evidence, not physical measurements.

Understand

Choose a common service and lifecycle boundary

A low operating-emissions number is not a complete lifecycle comparison. Begin with a functional unit: one kWh of electricity delivered at the load. Specify how much service will be delivered over the chosen lifetime and which stages count. Requested but unserved electricity cannot be included as delivered service in the denominator.

The original cards below compare two unnamed devices. Their coefficients are teaching assumptions, not extracted technology emissions factors. Read the included stages before calculating; adding a stage already included in a coefficient would double-count its burden.

Choose the denominator and lifetime boundary

Two unnamed fictional devices deliver the same service: one kWh electricity at the load. Let L be lifetime delivered electricity in kWh. Predict whether a lower operating factor always produces a lower total burden. These factors are original teaching assumptions, not observed technology data or factors attached to the dispatch lab.

Extraction and manufactureInstallation and operationEnd-of-life

Text boundary: extraction, manufacturing, transport, installation, operation and end-of-life. Stipulated fixed embodied burdens include all listed fixed stages; operating factors include upstream operational supply and use. Assume no replacement and no recycling credit. Do not count a fixed stage again inside operation.

A: 20 kg CO₂e fixed + 0.4 kg CO₂e per delivered kWh. B: 80 kg CO₂e fixed + 0.1 kg CO₂e per delivered kWh. Thus A(L) = 20 + 0.4L and B(L) = 80 + 0.1L, both in kg CO₂e. CO₂e expresses greenhouse-gas burden on a common carbon-dioxide-equivalent basis; the same supplied accounting basis applies to both.

Same delivered service within each row
Lifetime service L, kWh	A, kg CO₂e	B, kg CO₂e	Lower supplied total
100	60	90	A
200	100	100	Equal
1000	420	180	B

Check the ranking reversal

Equality requires 20 + 0.4L = 80 + 0.1L, so 0.3L = 60 and L = 200 kWh. At 100 kWh, A totals 60 versus B’s 90 kg CO₂e; at 1000 kWh, A totals 420 versus B’s 180. The operating factor alone cannot settle the ranking. An unserved kWh cannot be counted as delivered service in the denominator.

List what is missing before selecting a technology: water, land, material extraction, local pollution, waste, access and reliability are not ranked by these CO₂e totals. Neither device is identified with a real technology. NREL’s 2021 lifecycle greenhouse-gas update, NREL/FS-6A50-80580 supports explicit lifecycle and delivered-energy boundaries; its reviewed literature is not the source of these fictional factors.

Separate fixed and service-dependent burdens

Device A has 20 kg CO2e fixed embodied burden and 0.4 kg CO2e per delivered kWh in operation. Device B has 80 kg fixed and 0.1 per delivered kWh. CO2e expresses greenhouse-gas contributions using an equivalence metric; these particular values are stipulated for comparison, not measurements of specific equipment.

Fixed burdens include the supplied extraction, manufacturing, transport, installation and end-of-life account. Operating factors include the stipulated upstream operational supply and use. Assume no replacements and no recycling credit. Keep those exclusions visible because changing them could change the result.

Let L be lifetime electricity delivered in kWh. A’s total is 20 + 0.4L; B’s is 80 + 0.1L, both in kg CO2e. The fixed term has units kg, while kg/kWh multiplied by kWh gives the same unit. Explain that unit cancellation before adding the terms.

Find a ranking reversal rather than a universal winner

For L = 100 kWh, A totals 20 + 40 = 60 kg CO2e and B totals 80 + 10 = 90. At L = 1,000, A totals 420 while B totals 180. B’s lower operating factor outweighs its larger fixed burden only after sufficient delivered service under these assumptions.

Find the equality by solving 20 + 0.4L = 80 + 0.1L. Subtracting 0.1L and 20 gives 0.3L = 60, so L = 200 kWh. Both totals are 100 kg CO2e there. This crossover is a consequence of the supplied linear factors, not a physical lifetime or reliability prediction.

Make a two-column table for the three service amounts and state the changing conclusion. The NREL lifecycle summary provides context for lifecycle boundaries and variation. It supplies none of the fictional A/B coefficients used here, and a literature distribution would not be a site’s exact measured impact.

Keep dispatch and lifecycle evidence separate

The live dispatch model has no carbon factors for its generation packets or grid imports. Capture a case to identify served electricity, loss and unserved demand, but do not multiply those by the lifecycle card factors as though the cards describe its equipment. The two activities have deliberately separate assumptions.

Similarly, a lower modeled CO2e total does not rank water use, land occupation, extraction, local pollution, waste, access or reliability. Add those questions to your decision table as unresolved evidence needs, not invented numerical scores. A recommendation must identify which objective it prioritizes and which effects remain unknown.

Transfer: test another service level

Use the same fictional devices for 300 kWh delivered over the stated lifetime. Calculate both totals, compare them and explain why the lower result does not justify a universal environmental ranking. State how an unexpectedly short lifetime could matter.

Check the energy-lifecycle transfer

A gives 20 + 120 = 140 kg CO2e; B gives 80 + 30 = 110. B is lower for this service amount and boundary. Below the 200-kWh crossover A would be lower under the same factors, so delivered lifetime service matters. Neither result supplies the missing water, material, land or reliability comparison.

Apply

Public practice checks a specific claim. It does not establish independent mastery.

Explain why unserved demand cannot count as delivered service and CO2e alone cannot rank all impacts.

Your explanation and limitations

Continue

Completion requires a saved prediction, at least one capture and a reflection. Presence checks do not grade your reasoning.

Skipping retains experiments and awards no mastery.

Previous: Separate efficiency from service demand Next: Stress-test an energy recommendation

Save a science backup or import one

Science work is stored locally in this browser, separately from mathematics and AI. It does not sync automatically. Use this science-only backup; this checkout's older all-subject export does not include science.

A legacy file is available only when the complete snapshot fits the 36 MB limit. For larger snapshots, prepare a complete file set below; never discard notebooks to make a smaller file.

Choose a science backup (maximum 36 MB)

Matching imported notebook drafts replace their current drafts. Omitted lessons and known first attempts remain. Export your current work first if you want to retain both drafts.

Complete file sets and course backups

A file set can hold more work than one science file. Keep its manifest and every part together. Each file is limited to 36 MB. This format needs this version of LearnAI or a compatible newer version; older versions can use only the legacy single-file backup above.

Export scope

The set includes every saved science course and global continuation at this moment. Later edits need a new export. A conflicting tab exports its own visible work, which may differ from saved work in another tab.

Choose the manifest and all parts together

0 file(s) selected. File order and filenames do not determine identity. Missing, changed or conflicting parts block the entire restore; no good part is applied by itself.

Science storage: loading. No account or remote computation is required.