# Klima Halowerk Fuel CO2 Emissions Calculator

> Klima Halowerk Fuel CO2 Emissions Calculator is a paid API for AI agents from klima.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-28).

Calculates tank-to-wheel (TTW) and well-to-wheel (WTW) fuel combustion CO2 emissions from user-supplied quantity, unit, and published emission factors.

## Facts

- Endpoint: POST https://klima.halowerk.com/v1/fuel-co2?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/klima-halowerk-fuel-co2-emissions-calculator-73705ae3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_j7QPu4QyVOGCtSMZRTKhS

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability klima-halowerk-fuel-co2-emissions-calculator-73705ae3 -d '<json body>'
```

Example prompt: Calculate the TTW and WTW CO2 emissions for burning 5000 litres of diesel — the TTW factor is 2.68 kg CO2e/litre and WTW factor is 3.17 kg CO2e/litre, sourced from the DEFRA 2023 emission factors report published on 2023-06-01.

## When to prefer this

Choose this endpoint when you have a known fuel quantity and unit plus separately obtained published TTW and/or WTW emission factors and need a transparent, source-disclosed calculation. It is ideal for carbon accounting workflows where audit trails and method disclosure are required. Prefer it over generic calculators when you need the source citation and factor provenance preserved in the output, or when you are building multi-step pipelines that first look up factors (via sibling endpoints) and then apply them.

## Known failure modes

- Missing required fields (unit, quantity, or factors) returns null for affected values with those fields listed in unavailable_fields
- Invalid URI format for source URL returns validation error
- Quantity or factor values outside allowed range (0 to 1e12) return schema validation error
- Malformed published_at date-time format causes request rejection
- Both ttw_factor and wtw_factor omitted results in null emission outputs with both listed as unavailable

## How this service works

Calculates TTW and WTW fuel emissions from separately published factors. Missing facts are returned as null and named in unavailable_fields where applicable. Derived values disclose their method; source-backed values disclose source, time window and age. This is neither legal advice nor customs advice.

## Output

Returns calculated TTW and WTW emission totals (in CO2e units consistent with the supplied factors), the computation method used, source attribution including publication URL, title, and date, and a list of any unavailable_fields that could not be computed due to missing inputs.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType"
   ],
   "properties": {
    "type": {
     "const": "http"
    },
    "method": {
     "const": "POST"
    },
    "bodyType": {
     "const": "json"
    },
    "schemaUrl": {
     "type": "string",
     "format": "uri"
    },
    "exampleUrl": {
     "type": "string",
     "format": "uri"
    }
   },
   "additionalProperties": true
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "const": "json"
    },
    "schemaUrl": {
     "type": "string",
     "format": "uri"
    },
    "exampleUrl": {
     "type": "string",
     "format": "uri"
    }
   },
   "additionalProperties": true
  }
 },
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/klima-halowerk-fuel-co2-emissions-calculator-73705ae3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from klima.halowerk.com](https://www.zero.xyz/host/klima.halowerk.com/llms.txt)