diff --git a/web/src/components/CaseBuilder/ThermalUnits.tsx b/web/src/components/CaseBuilder/ThermalUnits.tsx
index acde078..94fdd24 100644
--- a/web/src/components/CaseBuilder/ThermalUnits.tsx
+++ b/web/src/components/CaseBuilder/ThermalUnits.tsx
@@ -27,6 +27,11 @@ import {
 } from "../../core/fixtures";
 import { ColumnDefinition } from "tabulator-tables";
 import { offerDownload } from "../Common/io";
+import {
+  createThermalUnit,
+  deleteGenerator,
+  renameGenerator,
+} from "../../core/Operations/generatorOps";
 
 export const ThermalUnitsColumnSpec: ColumnSpec[] = [
   {
@@ -155,17 +160,17 @@ const ThermalUnitsComponent = (props: CaseBuilderSectionProps) => {
   };
 
   const onAdd = () => {
-    // const [newScenario, err] = createThermalUnit(props.scenario);
-    // if (err) {
-    //   props.onError(err.message);
-    //   return;
-    // }
-    // props.onDataChanged(newScenario);
+    const [newScenario, err] = createThermalUnit(props.scenario);
+    if (err) {
+      props.onError(err.message);
+      return;
+    }
+    props.onDataChanged(newScenario);
   };
 
   const onDelete = (name: string): ValidationError | null => {
-    // const newScenario = deleteGenerator(name, props.scenario);
-    // props.onDataChanged(newScenario);
+    const newScenario = deleteGenerator(name, props.scenario);
+    props.onDataChanged(newScenario);
     return null;
   };
 
@@ -192,16 +197,16 @@ const ThermalUnitsComponent = (props: CaseBuilderSectionProps) => {
     oldName: string,
     newName: string,
   ): ValidationError | null => {
-    // const [newScenario, err] = renameGenerator(
-    //   oldName,
-    //   newName,
-    //   props.scenario,
-    // );
-    // if (err) {
-    //   props.onError(err.message);
-    //   return err;
-    // }
-    // props.onDataChanged(newScenario);
+    const [newScenario, err] = renameGenerator(
+      oldName,
+      newName,
+      props.scenario,
+    );
+    if (err) {
+      props.onError(err.message);
+      return err;
+    }
+    props.onDataChanged(newScenario);
     return null;
   };
 
diff --git a/web/src/components/Common/Forms/DataTable.tsx b/web/src/components/Common/Forms/DataTable.tsx
index 8bf78af..9c816c0 100644
--- a/web/src/components/Common/Forms/DataTable.tsx
+++ b/web/src/components/Common/Forms/DataTable.tsx
@@ -129,7 +129,9 @@ export const generateTableData = (
           break;
         case "number[N]":
           for (let i = 0; i < spec.length!; i++) {
-            entry[`${spec.title} ${i + 1}`] = entryData[spec.title][i] || "";
+            let v = entryData[spec.title][i];
+            if (v === undefined || v === null) v = "";
+            entry[`${spec.title} ${i + 1}`] = v;
           }
           break;
         default:
diff --git a/web/src/core/Operations/generatorOps.test.ts b/web/src/core/Operations/generatorOps.test.ts
index a2616ba..1badef1 100644
--- a/web/src/core/Operations/generatorOps.test.ts
+++ b/web/src/core/Operations/generatorOps.test.ts
@@ -9,21 +9,24 @@ import assert from "node:assert";
 import {
   changeProfiledUnitData,
   createProfiledUnit,
+  createThermalUnit,
   deleteGenerator,
   renameGenerator,
 } from "./generatorOps";
+import { ValidationError } from "../Validation/validate";
 
 test("createProfiledUnit", () => {
   const [newScenario, err] = createProfiledUnit(TEST_DATA_1);
   assert(err === null);
   assert.equal(Object.keys(newScenario.Generators).length, 4);
-  assert.deepEqual(newScenario.Generators["pu3"], {
-    Bus: "b1",
-    Type: "Profiled",
-    "Cost ($/MW)": 0,
-    "Maximum power (MW)": [0, 0, 0, 0, 0],
-    "Minimum power (MW)": [0, 0, 0, 0, 0],
-  });
+  assert("pu3" in newScenario.Generators);
+});
+
+test("createThermalUnit", () => {
+  const [newScenario, err] = createThermalUnit(TEST_DATA_1);
+  assert(err === null);
+  assert.equal(Object.keys(newScenario.Generators).length, 4);
+  assert("g2" in newScenario.Generators);
 });
 
 test("createProfiledUnit with blank file", () => {
@@ -34,7 +37,7 @@ test("createProfiledUnit with blank file", () => {
 
 test("changeProfiledUnitData", () => {
   let scenario = TEST_DATA_1;
-  let err = null;
+  let err: ValidationError | null;
   [scenario, err] = changeProfiledUnitData(
     "pu1",
     "Cost ($/MW)",
@@ -71,7 +74,7 @@ test("changeProfiledUnitData with invalid bus", () => {
 test("deleteGenerator", () => {
   const newScenario = deleteGenerator("pu1", TEST_DATA_1);
   assert.equal(Object.keys(newScenario.Generators).length, 2);
-  assert("gen1" in newScenario.Generators);
+  assert("g1" in newScenario.Generators);
   assert("pu2" in newScenario.Generators);
 });
 
diff --git a/web/src/core/Operations/generatorOps.ts b/web/src/core/Operations/generatorOps.ts
index bac9607..8968aa5 100644
--- a/web/src/core/Operations/generatorOps.ts
+++ b/web/src/core/Operations/generatorOps.ts
@@ -14,13 +14,20 @@ import {
 } from "./commonOps";
 import { ProfiledUnitsColumnSpec } from "../../components/CaseBuilder/ProfiledUnits";
 
+const assertBusesNotEmpty = (
+  scenario: UnitCommitmentScenario,
+): ValidationError | null => {
+  if (Object.keys(scenario.Buses).length === 0)
+    return { message: "Profiled unit requires an existing bus." };
+  return null;
+};
+
 export const createProfiledUnit = (
   scenario: UnitCommitmentScenario,
 ): [UnitCommitmentScenario, ValidationError | null] => {
-  const busNames = Object.keys(scenario.Buses);
-  if (busNames.length === 0) {
-    return [scenario, { message: "Profiled unit requires an existing bus." }];
-  }
+  const err = assertBusesNotEmpty(scenario);
+  if (err) return [scenario, err];
+  const busName = Object.keys(scenario.Buses)[0]!;
   const timeslots = generateTimeslots(scenario);
   const name = generateUniqueName(scenario.Generators, "pu");
   return [
@@ -29,7 +36,7 @@ export const createProfiledUnit = (
       Generators: {
         ...scenario.Generators,
         [name]: {
-          Bus: busNames[0]!,
+          Bus: busName,
           Type: "Profiled",
           "Cost ($/MW)": 0,
           "Minimum power (MW)": Array(timeslots.length).fill(0),
@@ -41,6 +48,41 @@ export const createProfiledUnit = (
   ];
 };
 
+export const createThermalUnit = (
+  scenario: UnitCommitmentScenario,
+): [UnitCommitmentScenario, ValidationError | null] => {
+  const err = assertBusesNotEmpty(scenario);
+  if (err) return [scenario, err];
+  const busName = Object.keys(scenario.Buses)[0]!;
+  const name = generateUniqueName(scenario.Generators, "g");
+  return [
+    {
+      ...scenario,
+      Generators: {
+        ...scenario.Generators,
+        [name]: {
+          Bus: busName,
+          Type: "Thermal",
+          "Production cost curve (MW)": [0],
+          "Production cost curve ($)": [0],
+          "Startup costs ($)": [0],
+          "Startup delays (h)": [1],
+          "Ramp up limit (MW)": "",
+          "Ramp down limit (MW)": "",
+          "Startup limit (MW)": "",
+          "Shutdown limit (MW)": "",
+          "Minimum downtime (h)": 1,
+          "Minimum uptime (h)": 1,
+          "Initial status (h)": -24,
+          "Initial power (MW)": 0,
+          "Must run?": false,
+        },
+      },
+    },
+    null,
+  ];
+};
+
 export const changeProfiledUnitData = (
   generator: string,
   field: string,
diff --git a/web/src/core/fixtures.test.ts b/web/src/core/fixtures.test.ts
index cee79b1..7c049a9 100644
--- a/web/src/core/fixtures.test.ts
+++ b/web/src/core/fixtures.test.ts
@@ -13,7 +13,7 @@ export const TEST_DATA_1: UnitCommitmentScenario = {
     b3: { "Load (MW)": [27.3729, 26.29698, 25.58005, 25.15675, 25.4268] },
   },
   Generators: {
-    gen1: {
+    g1: {
       Bus: "b1",
       Type: "Thermal",
       "Production cost curve (MW)": [100.0, 110.0, 130.0, 135.0],
diff --git a/web/src/core/fixtures.tsx b/web/src/core/fixtures.tsx
index 2061556..9130245 100644
--- a/web/src/core/fixtures.tsx
+++ b/web/src/core/fixtures.tsx
@@ -27,10 +27,10 @@ export interface ThermalUnit {
   "Production cost curve ($)": number[];
   "Startup costs ($)": number[];
   "Startup delays (h)": number[];
-  "Ramp up limit (MW)": number;
-  "Ramp down limit (MW)": number;
-  "Startup limit (MW)": number;
-  "Shutdown limit (MW)": number;
+  "Ramp up limit (MW)": number | "";
+  "Ramp down limit (MW)": number | "";
+  "Startup limit (MW)": number | "";
+  "Shutdown limit (MW)": number | "";
   "Minimum downtime (h)": number;
   "Minimum uptime (h)": number;
   "Initial status (h)": number;
@@ -158,7 +158,7 @@ export const TEST_SCENARIO: UnitCommitmentScenario = {
       ],
       "Cost ($/MW)": 50.0,
     },
-    gen1: {
+    g1: {
       Bus: "b1",
       Type: "Thermal",
       "Production cost curve (MW)": [100.0, 110.0, 130.0, 135.0],