Why Spanner Re² wood cogeneration plants

When JS Baird and Sons, Scotston Farm, Angus (customer of Spanner Re² since 2014) were investigating further improvements to their renewable portfolio, they happened across an emerging technology, Gasification. Wood gas has been used for many years in small scale installations as a substitute for petrol. The great advantage of the technology is that instead of burning woodchips in a biomass burner, the gasifier converts the wood chip into ‘syngas’ which is then used to drive a CHP.

 

Spanner Holz-Kraft

Spanner Holz-Kraft was chosen as the most experienced manufacturers of mass produced, small scale wood gas units. Since 2009 they have produced over 500 identical ‘cogeneration’ gasifiers (with some having over 40,000 hours’ running), and sold them all over Europe. Spanner has two principle units, a 3O kw electrical output producing 73 kw heat and a 45 kw electrical output producing 108 kw of heat.The units can be connected in multiple installs to produce which ever requirement of heat or power is needed. For JS Baird and Sons, one unit was sufficient to provide all the electricity required on the farm including a 25,000 broiler shed, a 200 t on-floor grain drying unit and two houses. The heat is added to the existing buffer tank which runs the drying floor and heats the broiler shed. It is on a scale that complements the existing setup at the farm. The unit is a simple, robust, efficient module that is both low cost and reliable.

Ordering and Training

After a tour of five very different Spanner installations in Germany, a contract was signed with delivery only 4 weeks later. Members of the farm and a specialist installer were given training in Germany prior to installation.

Installation

The construction of the install area had to be a perfect combination of high insulation and good ventilation. The units are located separately with the gasifier ‘pallet’ located in the ‘hot room’ and the engine generator CHP installed in the ‘cool room1A simple climate control computer operates the single tan ventilation. This is also connected to the Carbon Monoxide monitoring equipment which ensures the unit is operated in a safe environment. There is also an external emergency switch, warning horn and automatic shutdown.

The unit is not just a simple on and off - it requires an understanding of the process from chip store to filtration to engine running. A cold start needs the gas flared, to allow the system to heat up without sending cold gas into the engine. After some alterations to the wiring and temperature sensors, the units are switched on and rise immediately to full output.

JS Baird and Sons took the simple option to buy timber and hire a chipper to create the fuel. This process is important as the quality and moisture content of the chip is paramount to reliable running.

Warranty, service and backup Spanner gives a basic one year warranty, and they have a dedicated service team to provide parts and technical advice. The unit comes with a box of replacement components. There is no UK based seller, but support is available from a small network of owners. This unusual dealership arrangement is compensated by the purchase price, which is vastly lower than their competitors.

Ofgem accreditation

One drawback is the form filling. The complex nature of the concept and engineering is mirrored by the complex regulation by OFGEM.

There are three applications: Renewable obligation certificate (ROC), RHi for Biogas combustion and RHi for Solid biomass produced by the gasifier reformer process.

Payback

Payback for this installation must, alter all the cuts, rank as the most lucrative package available in the UK. Once all of the applications are complete the tariffs for each, along with energy saving and grid export, produce a payback of between two to three years. It goes without saying that the less energy is imported to a site, the better the payback. In the current climate of low arable prices, an installation like this can go a long way to securing the future of a farming enterprise with the holy trinity of low carbon energy, diversification and profitability.