Physics world has a review of the Arata cold fusion research This information is a review of the Arata cold fusion work at the LENR-CANR site. [Low Energy Nuclear Reactions, also known as Cold Fusion. (CANR, Chemically Assisted Nuclear Reaction)]
Based on 0.5 to 1 degree celsius of excess heat for one liter of water for 5000 minutes then it appears to be about 200-400 kwh of excess heat.
A deuterium (cold fusion) versus hydrogen (ordinary chemical) experiment is performed by Arata. There is always a significant temperature difference between T (inside, Tin) and T(surface of the energy cell, Ts), indicating that the sample and cell are not reaching equilibrium. After 300 minutes the Tin of the deuterium experiment is about 28 °C (4 °C warmer than ambient), while Tin/Ts of the hydrogen experiment is at about 25 °C (1 °C warmer than ambient).
Arata claims that, given the large amount of power involved, this must be some form of fusion — what he prefers to call “solid fusion”. This can be described, he says, by the following equation:
D + D = 4He + heat
The deuterium experiments remain 1 °C or more than ambient for at least 3000 minutes while still exhibiting the temperature difference between the sample and the cell, Tin and Ts.
20 °C calorie: the amount of energy required to warm 1 g of air-free water from 19.5 °C to 20.5 °C at a constant pressure of 101.325 kPa (1 atm). This is about 4.182 J. The experiment appears to have been dealing with one liter of water. So one extra degree for 5000 minutes would be 300,000 seconds times 4172 joules which is 1251.6 megajoules. This is 347.6 kwh. Being able to convert that thermal energy into electricity would not be efficient without boosting the temperature.